#xiao — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #xiao, aggregated by home.social.
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XIAO ESP32-C3 MIDI Synthesizer – Part 6
Expanding on my previous posts, I thought it might be interesting to see how I might be able to add some additional IO to the MIDI Synth. This is an exploration of some options there.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
- Getting Started with the XIAO MIDI Synthesizer
- XIAO SAMD21, Arduino and MIDI
- XIAO SAMD21, Arduino and MIDI – Part 6
If you are new to microcontrollers, see the Getting Started pages.
The Synth Grove Connector
One option to immediately explore for me was the Grove connector on the Synth – highlighted by the blue rectangle in the photo below. I’m thinking at this stage of the XIAO Expander Module (more here) and how that might give some options for easily hooking up to the Synth.
There one obvious issue with this, and one not so obvious issue.
First, of course, there is no access to this connector through the case. My initial thought was to simply remove the PCB from the case and use it as a stand-alone board. On initial inspection it seemed that there were two screws holding it down. Not so, a more thorough inspection (after remove the two screws and still not being able to remove it), revealed a third screw underneath the “light pipe” for the LEDs.
Unfortunately that light pipe is pretty well wedged into the case making removal particularly tricky. But without removing the light pipe, it isn’t possible to get to the screw at all.
I did wonder about making a hole in the 3D printed case. A better option might be to get hold of the published 3D print files and add a hole and make my own (they are available via the product page).
But both options would probably end up changing the original case somehow – even if printing my own, I still need to get the original PCB out somehow and that brings me back to the light pipe issue.
The second issue isn’t quite so obvious. In that photo we can see that the pins for the Grove connector are labelled as follows (top to bottom):
- NC
- TX
- 5V
- GND
The UART on the XIAO expander board, which I’d like to use, is labelled:
- RX7
- TX6
- 3V3
- GND
Checking in with the Synth schematic, the connector is wired as follows:
SYS_MIDI connects to the MIDI_IN pin of the SAM2695, so actually connecting “TX to TX” in this instance should be ok.
5V might be an issue though, as it really does look like (to me) that it really means 5V – it is the input to the TPL740F33 that generates the 3V3 power signal, as well as feeding the amplifier directly. The datasheet of the TPL740F33 does seem to imply that if receiving 3V3 it can still generate 3V3 so it might be ok? The amplifier obviously won’t be as powerful though running off 3V3.
Anyway, for now, instead I’ve just opted to use the GPIO again, wired into the expansion sockets with the XIAO removed.
At the XIAO expander end, I’ve used the additional pins rather than the Grove connector, as they support a 5V output.
The downsides to this approach:
- I’m not using the Grove connectors, which would have been really neat.
- I have no access to the four buttons on the XIAO MIDI Synth.
But I do now have access to two I2C Grove connectors, a GPIO Grove, and the RX part of the UART Grove too as well as the on-board display.
If a XIAO SAMD21 is used, then the previous code for USB to the Synth can be used directly – see XIAO ESP32-C3 MIDI Synthesizer – Part 2.
If the XIAO ESP32-C3 is used, then an additional serial MIDI connection is required. This can be connected to the Grove UART connector (using the RX pin, and leaving TX unconnected) or the RX pin of the additional 8-way pin header on the expansion board. Then the code from this will work directly: XIAO ESP32-C3 MIDI Synthesizer – Part 5.
Adding a Display and Program Control
I already have some code that has done this for a XIAO on an expansion board here XIAO SAMD21, Arduino and MIDI – Part 6.
But for this to work usefully with the Synth module, I need to adjust the routing so that MIDI goes from USB to serial, but the program change messages are also sent via serial to the synth module. That has already been address in previous parts, to I just need to merge the code with that from XIAO ESP32-C3 MIDI Synthesizer – Part 4.
This is the result.
There is a bit of jitter on the analog pot, but that is only because I’m using the original fairly simplified algorithm to detect changes. If I was fussed about it, I’d reuse the averaging class from Arduino MIDI Atari Paddles. And to be honest, a capacitor on the pot would probably go quite a long way too…
As a test, I also powered the device from the Grove UART port connecting it as follows:
- Expander GND – GND Synth
- Expander 3V3 – 5V IN Synth
- Expander TX – RX/D6 Synth
- Expander RX – N/C
And this all worked fine. So I think a Grove to Grove lead would work fine if I had access to the Synth’s Grove port.
This does mean that the exact same code can work with the M5 Synth module using a Grove to Grove lead. The downside of this, even though it is a lot simpler in connectivity terms, is that there is now external audio out like there is on the XIAO Synth.
For completeness the same code can be used with the XIAO ESP32-C3 and serial MIDI, see the photo at the start of this blog.
To turn off all USB handling in the code, the following must be commented out:
//#define HAS_USB
//#define SER_TO_USB
//#define MIDI_USB_PCCCFor other parts of the code, the Arduino abstraction for A0 maps over to the ESP32-C3 fine. The only thing to watch out for is the increased analog resolution from 10 to 12 bits, but a call to analogReadResolution(10) drops that back to the expected 10 bits.
Oh and the Serial port to use is different:
- XIAO SAMD21: Serial1
- XIAO ESP32-C3: Serial0
Closing Thoughts
If I can be bothered, it would be nice to actually display the General MIDI voice name on the display. The SAM2695 also has its MT-32 mode, so having some means of selecting that might be interesting too.
And so far I’ve largely only messed about with driving it on a single MIDI channel, so there is a lot more that could be done there.
Kevin
#controlChange #esp32c3 #midi #programChange #SAM2695 #samd21 #usbMidi #xiao
-
XIAO ESP32-C3 MIDI Synthesizer – Part 6
Expanding on my previous posts, I thought it might be interesting to see how I might be able to add some additional IO to the MIDI Synth. This is an exploration of some options there.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
- Getting Started with the XIAO MIDI Synthesizer
- XIAO SAMD21, Arduino and MIDI
- XIAO SAMD21, Arduino and MIDI – Part 6
If you are new to microcontrollers, see the Getting Started pages.
The Synth Grove Connector
One option to immediately explore for me was the Grove connector on the Synth – highlighted by the blue rectangle in the photo below. I’m thinking at this stage of the XIAO Expander Module (more here) and how that might give some options for easily hooking up to the Synth.
There one obvious issue with this, and one not so obvious issue.
First, of course, there is no access to this connector through the case. My initial thought was to simply remove the PCB from the case and use it as a stand-alone board. On initial inspection it seemed that there were two screws holding it down. Not so, a more thorough inspection (after remove the two screws and still not being able to remove it), revealed a third screw underneath the “light pipe” for the LEDs.
Unfortunately that light pipe is pretty well wedged into the case making removal particularly tricky. But without removing the light pipe, it isn’t possible to get to the screw at all.
I did wonder about making a hole in the 3D printed case. A better option might be to get hold of the published 3D print files and add a hole and make my own (they are available via the product page).
But both options would probably end up changing the original case somehow – even if printing my own, I still need to get the original PCB out somehow and that brings me back to the light pipe issue.
The second issue isn’t quite so obvious. In that photo we can see that the pins for the Grove connector are labelled as follows (top to bottom):
- NC
- TX
- 5V
- GND
The UART on the XIAO expander board, which I’d like to use, is labelled:
- RX7
- TX6
- 3V3
- GND
Checking in with the Synth schematic, the connector is wired as follows:
SYS_MIDI connects to the MIDI_IN pin of the SAM2695, so actually connecting “TX to TX” in this instance should be ok.
5V might be an issue though, as it really does look like (to me) that it really means 5V – it is the input to the TPL740F33 that generates the 3V3 power signal, as well as feeding the amplifier directly. The datasheet of the TPL740F33 does seem to imply that if receiving 3V3 it can still generate 3V3 so it might be ok? The amplifier obviously won’t be as powerful though running off 3V3.
Anyway, for now, instead I’ve just opted to use the GPIO again, wired into the expansion sockets with the XIAO removed.
At the XIAO expander end, I’ve used the additional pins rather than the Grove connector, as they support a 5V output.
The downsides to this approach:
- I’m not using the Grove connectors, which would have been really neat.
- I have no access to the four buttons on the XIAO MIDI Synth.
But I do now have access to two I2C Grove connectors, a GPIO Grove, and the RX part of the UART Grove too as well as the on-board display.
If a XIAO SAMD21 is used, then the previous code for USB to the Synth can be used directly – see XIAO ESP32-C3 MIDI Synthesizer – Part 2.
If the XIAO ESP32-C3 is used, then an additional serial MIDI connection is required. This can be connected to the Grove UART connector (using the RX pin, and leaving TX unconnected) or the RX pin of the additional 8-way pin header on the expansion board. Then the code from this will work directly: XIAO ESP32-C3 MIDI Synthesizer – Part 5.
Adding a Display and Program Control
I already have some code that has done this for a XIAO on an expansion board here XIAO SAMD21, Arduino and MIDI – Part 6.
But for this to work usefully with the Synth module, I need to adjust the routing so that MIDI goes from USB to serial, but the program change messages are also sent via serial to the synth module. That has already been address in previous parts, to I just need to merge the code with that from XIAO ESP32-C3 MIDI Synthesizer – Part 4.
This is the result.
There is a bit of jitter on the analog pot, but that is only because I’m using the original fairly simplified algorithm to detect changes. If I was fussed about it, I’d reuse the averaging class from Arduino MIDI Atari Paddles. And to be honest, a capacitor on the pot would probably go quite a long way too…
As a test, I also powered the device from the Grove UART port connecting it as follows:
- Expander GND – GND Synth
- Expander 3V3 – 5V IN Synth
- Expander TX – RX/D6 Synth
- Expander RX – N/C
And this all worked fine. So I think a Grove to Grove lead would work fine if I had access to the Synth’s Grove port.
This does mean that the exact same code can work with the M5 Synth module using a Grove to Grove lead. The downside of this, even though it is a lot simpler in connectivity terms, is that there is now external audio out like there is on the XIAO Synth.
For completeness the same code can be used with the XIAO ESP32-C3 and serial MIDI, see the photo at the start of this blog.
To turn off all USB handling in the code, the following must be commented out:
//#define HAS_USB
//#define SER_TO_USB
//#define MIDI_USB_PCCCFor other parts of the code, the Arduino abstraction for A0 maps over to the ESP32-C3 fine. The only thing to watch out for is the increased analog resolution from 10 to 12 bits, but a call to analogReadResolution(10) drops that back to the expected 10 bits.
Oh and the Serial port to use is different:
- XIAO SAMD21: Serial1
- XIAO ESP32-C3: Serial0
Closing Thoughts
If I can be bothered, it would be nice to actually display the General MIDI voice name on the display. The SAM2695 also has its MT-32 mode, so having some means of selecting that might be interesting too.
And so far I’ve largely only messed about with driving it on a single MIDI channel, so there is a lot more that could be done there.
Kevin
#controlChange #esp32c3 #midi #programChange #SAM2695 #samd21 #usbMidi #xiao
-
XIAO ESP32-C3 MIDI Synthesizer – Part 6
Expanding on my previous posts, I thought it might be interesting to see how I might be able to add some additional IO to the MIDI Synth. This is an exploration of some options there.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
- Getting Started with the XIAO MIDI Synthesizer
- XIAO SAMD21, Arduino and MIDI
- XIAO SAMD21, Arduino and MIDI – Part 6
If you are new to microcontrollers, see the Getting Started pages.
The Synth Grove Connector
One option to immediately explore for me was the Grove connector on the Synth – highlighted by the blue rectangle in the photo below. I’m thinking at this stage of the XIAO Expander Module (more here) and how that might give some options for easily hooking up to the Synth.
There one obvious issue with this, and one not so obvious issue.
First, of course, there is no access to this connector through the case. My initial thought was to simply remove the PCB from the case and use it as a stand-alone board. On initial inspection it seemed that there were two screws holding it down. Not so, a more thorough inspection (after remove the two screws and still not being able to remove it), revealed a third screw underneath the “light pipe” for the LEDs.
Unfortunately that light pipe is pretty well wedged into the case making removal particularly tricky. But without removing the light pipe, it isn’t possible to get to the screw at all.
I did wonder about making a hole in the 3D printed case. A better option might be to get hold of the published 3D print files and add a hole and make my own (they are available via the product page).
But both options would probably end up changing the original case somehow – even if printing my own, I still need to get the original PCB out somehow and that brings me back to the light pipe issue.
The second issue isn’t quite so obvious. In that photo we can see that the pins for the Grove connector are labelled as follows (top to bottom):
- NC
- TX
- 5V
- GND
The UART on the XIAO expander board, which I’d like to use, is labelled:
- RX7
- TX6
- 3V3
- GND
Checking in with the Synth schematic, the connector is wired as follows:
SYS_MIDI connects to the MIDI_IN pin of the SAM2695, so actually connecting “TX to TX” in this instance should be ok.
5V might be an issue though, as it really does look like (to me) that it really means 5V – it is the input to the TPL740F33 that generates the 3V3 power signal, as well as feeding the amplifier directly. The datasheet of the TPL740F33 does seem to imply that if receiving 3V3 it can still generate 3V3 so it might be ok? The amplifier obviously won’t be as powerful though running off 3V3.
Anyway, for now, instead I’ve just opted to use the GPIO again, wired into the expansion sockets with the XIAO removed.
At the XIAO expander end, I’ve used the additional pins rather than the Grove connector, as they support a 5V output.
The downsides to this approach:
- I’m not using the Grove connectors, which would have been really neat.
- I have no access to the four buttons on the XIAO MIDI Synth.
But I do now have access to two I2C Grove connectors, a GPIO Grove, and the RX part of the UART Grove too as well as the on-board display.
If a XIAO SAMD21 is used, then the previous code for USB to the Synth can be used directly – see XIAO ESP32-C3 MIDI Synthesizer – Part 2.
If the XIAO ESP32-C3 is used, then an additional serial MIDI connection is required. This can be connected to the Grove UART connector (using the RX pin, and leaving TX unconnected) or the RX pin of the additional 8-way pin header on the expansion board. Then the code from this will work directly: XIAO ESP32-C3 MIDI Synthesizer – Part 5.
Adding a Display and Program Control
I already have some code that has done this for a XIAO on an expansion board here XIAO SAMD21, Arduino and MIDI – Part 6.
But for this to work usefully with the Synth module, I need to adjust the routing so that MIDI goes from USB to serial, but the program change messages are also sent via serial to the synth module. That has already been address in previous parts, to I just need to merge the code with that from XIAO ESP32-C3 MIDI Synthesizer – Part 4.
This is the result.
There is a bit of jitter on the analog pot, but that is only because I’m using the original fairly simplified algorithm to detect changes. If I was fussed about it, I’d reuse the averaging class from Arduino MIDI Atari Paddles. And to be honest, a capacitor on the pot would probably go quite a long way too…
As a test, I also powered the device from the Grove UART port connecting it as follows:
- Expander GND – GND Synth
- Expander 3V3 – 5V IN Synth
- Expander TX – RX/D6 Synth
- Expander RX – N/C
And this all worked fine. So I think a Grove to Grove lead would work fine if I had access to the Synth’s Grove port.
This does mean that the exact same code can work with the M5 Synth module using a Grove to Grove lead. The downside of this, even though it is a lot simpler in connectivity terms, is that there is now external audio out like there is on the XIAO Synth.
For completeness the same code can be used with the XIAO ESP32-C3 and serial MIDI, see the photo at the start of this blog.
To turn off all USB handling in the code, the following must be commented out:
//#define HAS_USB
//#define SER_TO_USB
//#define MIDI_USB_PCCCFor other parts of the code, the Arduino abstraction for A0 maps over to the ESP32-C3 fine. The only thing to watch out for is the increased analog resolution from 10 to 12 bits, but a call to analogReadResolution(10) drops that back to the expected 10 bits.
Oh and the Serial port to use is different:
- XIAO SAMD21: Serial1
- XIAO ESP32-C3: Serial0
Closing Thoughts
If I can be bothered, it would be nice to actually display the General MIDI voice name on the display. The SAM2695 also has its MT-32 mode, so having some means of selecting that might be interesting too.
And so far I’ve largely only messed about with driving it on a single MIDI channel, so there is a lot more that could be done there.
Kevin
#controlChange #esp32c3 #midi #programChange #SAM2695 #samd21 #usbMidi #xiao
-
XIAO ESP32-C3 MIDI Synthesizer – Part 6
Expanding on my previous posts, I thought it might be interesting to see how I might be able to add some additional IO to the MIDI Synth. This is an exploration of some options there.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
- Getting Started with the XIAO MIDI Synthesizer
- XIAO SAMD21, Arduino and MIDI
- XIAO SAMD21, Arduino and MIDI – Part 6
If you are new to microcontrollers, see the Getting Started pages.
The Synth Grove Connector
One option to immediately explore for me was the Grove connector on the Synth – highlighted by the blue rectangle in the photo below. I’m thinking at this stage of the XIAO Expander Module (more here) and how that might give some options for easily hooking up to the Synth.
There one obvious issue with this, and one not so obvious issue.
First, of course, there is no access to this connector through the case. My initial thought was to simply remove the PCB from the case and use it as a stand-alone board. On initial inspection it seemed that there were two screws holding it down. Not so, a more thorough inspection (after remove the two screws and still not being able to remove it), revealed a third screw underneath the “light pipe” for the LEDs.
Unfortunately that light pipe is pretty well wedged into the case making removal particularly tricky. But without removing the light pipe, it isn’t possible to get to the screw at all.
I did wonder about making a hole in the 3D printed case. A better option might be to get hold of the published 3D print files and add a hole and make my own (they are available via the product page).
But both options would probably end up changing the original case somehow – even if printing my own, I still need to get the original PCB out somehow and that brings me back to the light pipe issue.
The second issue isn’t quite so obvious. In that photo we can see that the pins for the Grove connector are labelled as follows (top to bottom):
- NC
- TX
- 5V
- GND
The UART on the XIAO expander board, which I’d like to use, is labelled:
- RX7
- TX6
- 3V3
- GND
Checking in with the Synth schematic, the connector is wired as follows:
SYS_MIDI connects to the MIDI_IN pin of the SAM2695, so actually connecting “TX to TX” in this instance should be ok.
5V might be an issue though, as it really does look like (to me) that it really means 5V – it is the input to the TPL740F33 that generates the 3V3 power signal, as well as feeding the amplifier directly. The datasheet of the TPL740F33 does seem to imply that if receiving 3V3 it can still generate 3V3 so it might be ok? The amplifier obviously won’t be as powerful though running off 3V3.
Anyway, for now, instead I’ve just opted to use the GPIO again, wired into the expansion sockets with the XIAO removed.
At the XIAO expander end, I’ve used the additional pins rather than the Grove connector, as they support a 5V output.
The downsides to this approach:
- I’m not using the Grove connectors, which would have been really neat.
- I have no access to the four buttons on the XIAO MIDI Synth.
But I do now have access to two I2C Grove connectors, a GPIO Grove, and the RX part of the UART Grove too as well as the on-board display.
If a XIAO SAMD21 is used, then the previous code for USB to the Synth can be used directly – see XIAO ESP32-C3 MIDI Synthesizer – Part 2.
If the XIAO ESP32-C3 is used, then an additional serial MIDI connection is required. This can be connected to the Grove UART connector (using the RX pin, and leaving TX unconnected) or the RX pin of the additional 8-way pin header on the expansion board. Then the code from this will work directly: XIAO ESP32-C3 MIDI Synthesizer – Part 5.
Adding a Display and Program Control
I already have some code that has done this for a XIAO on an expansion board here XIAO SAMD21, Arduino and MIDI – Part 6.
But for this to work usefully with the Synth module, I need to adjust the routing so that MIDI goes from USB to serial, but the program change messages are also sent via serial to the synth module. That has already been address in previous parts, to I just need to merge the code with that from XIAO ESP32-C3 MIDI Synthesizer – Part 4.
This is the result.
There is a bit of jitter on the analog pot, but that is only because I’m using the original fairly simplified algorithm to detect changes. If I was fussed about it, I’d reuse the averaging class from Arduino MIDI Atari Paddles. And to be honest, a capacitor on the pot would probably go quite a long way too…
As a test, I also powered the device from the Grove UART port connecting it as follows:
- Expander GND – GND Synth
- Expander 3V3 – 5V IN Synth
- Expander TX – RX/D6 Synth
- Expander RX – N/C
And this all worked fine. So I think a Grove to Grove lead would work fine if I had access to the Synth’s Grove port.
This does mean that the exact same code can work with the M5 Synth module using a Grove to Grove lead. The downside of this, even though it is a lot simpler in connectivity terms, is that there is now external audio out like there is on the XIAO Synth.
For completeness the same code can be used with the XIAO ESP32-C3 and serial MIDI, see the photo at the start of this blog.
To turn off all USB handling in the code, the following must be commented out:
//#define HAS_USB
//#define SER_TO_USB
//#define MIDI_USB_PCCCFor other parts of the code, the Arduino abstraction for A0 maps over to the ESP32-C3 fine. The only thing to watch out for is the increased analog resolution from 10 to 12 bits, but a call to analogReadResolution(10) drops that back to the expected 10 bits.
Oh and the Serial port to use is different:
- XIAO SAMD21: Serial1
- XIAO ESP32-C3: Serial0
Closing Thoughts
If I can be bothered, it would be nice to actually display the General MIDI voice name on the display. The SAM2695 also has its MT-32 mode, so having some means of selecting that might be interesting too.
And so far I’ve largely only messed about with driving it on a single MIDI channel, so there is a lot more that could be done there.
Kevin
#controlChange #esp32c3 #midi #programChange #SAM2695 #samd21 #usbMidi #xiao
-
XIAO ESP32-C3 MIDI Synthesizer – Part 6
Expanding on my previous posts, I thought it might be interesting to see how I might be able to add some additional IO to the MIDI Synth. This is an exploration of some options there.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
- Getting Started with the XIAO MIDI Synthesizer
- XIAO SAMD21, Arduino and MIDI
- XIAO SAMD21, Arduino and MIDI – Part 6
If you are new to microcontrollers, see the Getting Started pages.
The Synth Grove Connector
One option to immediately explore for me was the Grove connector on the Synth – highlighted by the blue rectangle in the photo below. I’m thinking at this stage of the XIAO Expander Module (more here) and how that might give some options for easily hooking up to the Synth.
There one obvious issue with this, and one not so obvious issue.
First, of course, there is no access to this connector through the case. My initial thought was to simply remove the PCB from the case and use it as a stand-alone board. On initial inspection it seemed that there were two screws holding it down. Not so, a more thorough inspection (after remove the two screws and still not being able to remove it), revealed a third screw underneath the “light pipe” for the LEDs.
Unfortunately that light pipe is pretty well wedged into the case making removal particularly tricky. But without removing the light pipe, it isn’t possible to get to the screw at all.
I did wonder about making a hole in the 3D printed case. A better option might be to get hold of the published 3D print files and add a hole and make my own (they are available via the product page).
But both options would probably end up changing the original case somehow – even if printing my own, I still need to get the original PCB out somehow and that brings me back to the light pipe issue.
The second issue isn’t quite so obvious. In that photo we can see that the pins for the Grove connector are labelled as follows (top to bottom):
- NC
- TX
- 5V
- GND
The UART on the XIAO expander board, which I’d like to use, is labelled:
- RX7
- TX6
- 3V3
- GND
Checking in with the Synth schematic, the connector is wired as follows:
SYS_MIDI connects to the MIDI_IN pin of the SAM2695, so actually connecting “TX to TX” in this instance should be ok.
5V might be an issue though, as it really does look like (to me) that it really means 5V – it is the input to the TPL740F33 that generates the 3V3 power signal, as well as feeding the amplifier directly. The datasheet of the TPL740F33 does seem to imply that if receiving 3V3 it can still generate 3V3 so it might be ok? The amplifier obviously won’t be as powerful though running off 3V3.
Anyway, for now, instead I’ve just opted to use the GPIO again, wired into the expansion sockets with the XIAO removed.
At the XIAO expander end, I’ve used the additional pins rather than the Grove connector, as they support a 5V output.
The downsides to this approach:
- I’m not using the Grove connectors, which would have been really neat.
- I have no access to the four buttons on the XIAO MIDI Synth.
But I do now have access to two I2C Grove connectors, a GPIO Grove, and the RX part of the UART Grove too as well as the on-board display.
If a XIAO SAMD21 is used, then the previous code for USB to the Synth can be used directly – see XIAO ESP32-C3 MIDI Synthesizer – Part 2.
If the XIAO ESP32-C3 is used, then an additional serial MIDI connection is required. This can be connected to the Grove UART connector (using the RX pin, and leaving TX unconnected) or the RX pin of the additional 8-way pin header on the expansion board. Then the code from this will work directly: XIAO ESP32-C3 MIDI Synthesizer – Part 5.
Adding a Display and Program Control
I already have some code that has done this for a XIAO on an expansion board here XIAO SAMD21, Arduino and MIDI – Part 6.
But for this to work usefully with the Synth module, I need to adjust the routing so that MIDI goes from USB to serial, but the program change messages are also sent via serial to the synth module. That has already been address in previous parts, to I just need to merge the code with that from XIAO ESP32-C3 MIDI Synthesizer – Part 4.
This is the result.
There is a bit of jitter on the analog pot, but that is only because I’m using the original fairly simplified algorithm to detect changes. If I was fussed about it, I’d reuse the averaging class from Arduino MIDI Atari Paddles. And to be honest, a capacitor on the pot would probably go quite a long way too…
As a test, I also powered the device from the Grove UART port connecting it as follows:
- Expander GND – GND Synth
- Expander 3V3 – 5V IN Synth
- Expander TX – RX/D6 Synth
- Expander RX – N/C
And this all worked fine. So I think a Grove to Grove lead would work fine if I had access to the Synth’s Grove port.
This does mean that the exact same code can work with the M5 Synth module using a Grove to Grove lead. The downside of this, even though it is a lot simpler in connectivity terms, is that there is now external audio out like there is on the XIAO Synth.
For completeness the same code can be used with the XIAO ESP32-C3 and serial MIDI, see the photo at the start of this blog.
To turn off all USB handling in the code, the following must be commented out:
//#define HAS_USB
//#define SER_TO_USB
//#define MIDI_USB_PCCCFor other parts of the code, the Arduino abstraction for A0 maps over to the ESP32-C3 fine. The only thing to watch out for is the increased analog resolution from 10 to 12 bits, but a call to analogReadResolution(10) drops that back to the expected 10 bits.
Oh and the Serial port to use is different:
- XIAO SAMD21: Serial1
- XIAO ESP32-C3: Serial0
Closing Thoughts
If I can be bothered, it would be nice to actually display the General MIDI voice name on the display. The SAM2695 also has its MT-32 mode, so having some means of selecting that might be interesting too.
And so far I’ve largely only messed about with driving it on a single MIDI channel, so there is a lot more that could be done there.
Kevin
#controlChange #esp32c3 #midi #programChange #SAM2695 #samd21 #usbMidi #xiao
-
XIAO ESP32-C3 MIDI Synthesizer – Part 5
So I was somewhat guilty that I’d replaced the XIAO microcontroller in the last couple of parts to get USB MIDI, so in this one I put the original ESP32-C3 back in and now have a version of Part 4 for serial MIDI.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
https://makertube.net/w/wez7y8WrxrNgkF1F1QX2AX
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
If you are new to microcontrollers, see the Getting Started pages.
The Circuit
This goes back to adding a 3V3 compatible serial MIDI board using the XIAO GPIO breakout pins as described in Part 1.
This is powered from 3V3 and GND and connected to D6/RX (which may or may not be GPIO 6).
The Code
This is all the same code from Part 4 but with the USB handling removed and the bespoke serial port writing replaced with calls into the Arduino MIDI Library using Serial0 as the MIDI device:
MIDI_CREATE_INSTANCE(HardwareSerial, Serial0, MIDI);
void midiSendProgram (uint8_t prog) {
MIDI.sendProgramChange(prog, MIDI_CHANNEL);
}
void midiSendControl (uint8_t cmd, uint8_t d) {
MIDI.sendControlChange(cmd, d, MIDI_CHANNEL);
}
void setup() {
MIDI.begin(MIDI_CHANNEL);
...
}
void loop() {
MIDI.read();
...
}Once again I’m relying on the fact that the serial MIDI transport has an automatic MIDI THRU enabled between RX and TX.
Closing Thoughts
Whilst the USB MIDI host solution is a lot more convenient in terms of being able to plug in MIDI controllers, the serial MIDI version is a lot easier when it comes to programming and powering the device.
The video shows a PC streaming a MIDI file to the XIAO Synth whilst I’m changing volume and voice.
Kevin
-
XIAO ESP32-C3 MIDI Synthesizer – Part 5
So I was somewhat guilty that I’d replaced the XIAO microcontroller in the last couple of parts to get USB MIDI, so in this one I put the original ESP32-C3 back in and now have a version of Part 4 for serial MIDI.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
https://makertube.net/w/wez7y8WrxrNgkF1F1QX2AX
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
If you are new to microcontrollers, see the Getting Started pages.
The Circuit
This goes back to adding a 3V3 compatible serial MIDI board using the XIAO GPIO breakout pins as described in Part 1.
This is powered from 3V3 and GND and connected to D6/RX (which may or may not be GPIO 6).
The Code
This is all the same code from Part 4 but with the USB handling removed and the bespoke serial port writing replaced with calls into the Arduino MIDI Library using Serial0 as the MIDI device:
MIDI_CREATE_INSTANCE(HardwareSerial, Serial0, MIDI);
void midiSendProgram (uint8_t prog) {
MIDI.sendProgramChange(prog, MIDI_CHANNEL);
}
void midiSendControl (uint8_t cmd, uint8_t d) {
MIDI.sendControlChange(cmd, d, MIDI_CHANNEL);
}
void setup() {
MIDI.begin(MIDI_CHANNEL);
...
}
void loop() {
MIDI.read();
...
}Once again I’m relying on the fact that the serial MIDI transport has an automatic MIDI THRU enabled between RX and TX.
Closing Thoughts
Whilst the USB MIDI host solution is a lot more convenient in terms of being able to plug in MIDI controllers, the serial MIDI version is a lot easier when it comes to programming and powering the device.
The video shows a PC streaming a MIDI file to the XIAO Synth whilst I’m changing volume and voice.
Kevin
-
XIAO ESP32-C3 MIDI Synthesizer – Part 4
In Part 2 I looked at how to add USB MIDI to the XIAO MIDI Synthesizer and in Part 3 I looked at some of the properties of the SAM2695 synth chip itself. This post combines the two into a relatively simple, but playable, synth.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
https://makertube.net/w/kaZT6zPjKUmGQp17J15fMM
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
If you are new to microcontrollers, see the Getting Started pages.
The Circuit
I’m wanting to plug a USB MIDI keyboard into my XIAO Synth, so I’m going to swap the XIAO ESP32-C3 out once again for a XIAO SAMD21 as described in Part 2. A future post will go back and create a serial MIDI version using the unmodified XIAO Synth.
Recall that a source of 5V power is required, and below I’m just using the 5V USB passthrough from the original XIAO ESP32-C3.
There is one issue to watch out for in this kind of configuration. Depending on how the USB power is provided, there might not be a common ground point between the XIAO’s power and any audio amplification used.
Apparently GND is always passed through many USB charger blocks.
To prevent interference and noise, it may be necessary to ground the USB connection providing power.
The Code
I’m using a combination of the SAMD21 USB Host Library “USB MIDI Converter” example and some GPIO and MIDI handling.
The general thread of the code will be as follows:
loop():
Do any USB host processing (e.g. plug-and-play)
IF USB MIDI messages received THEN
Send to serial MIDI
IF any buttons pressed THEN
Handle button IO
Generate any additional MIDI messages as required
Send to serial MIDIIn particular it should be noted that the MIDI “listening” is one-way only USB to serial MIDI; and that any internal control events that generate MIDI are also only going one way – to serial MIDI.
The buttons will be used to do the following:
- Button 0 and 1: Program Select Up/Down
- Button 2 and 3: Channel Volume Up/Down
A much more sophisticated interface could be developed – e.g. using one of the buttons to change modes for the other buttons, to allow the selection of different things, but for now, this is plenty.
There are several layers to the code to allow this however, so I’ll cover them briefly here.
- Main Loop button IO: Checks for the main H->L, L->H, L->L, H->H events and calls functions for all but the last (buttons are pulled high so H->H means “nothing happening).
- Event functions for Pressed, Released, Hold which call program or volume handling functions as required.
- Program/volume handling functions that update the values and then trigger the appropriate MIDI messages to be sent.
- Functions to send a MIDI Program Change or Control Change message as required.
In the end I’ve only triggered events on button Pressed, so the Release and Hold functions don’t cause any further action to take place, but the model is there for use in the future if required.
Note: as I’m not using the Arduino MIDI Library, I just build PC or CC messages directly and call out to Serial1.Write as shown below.
void midiSendControl (uint8_t cmd, uint8_t d) {
uint8_t buf[3];
buf[0] = MIDI_CC | (MIDI_CHANNEL-1);
buf[1] = cmd;
buf[2] = d;
Serial1.write(buf, 3);
}Simple, but it works. Note PC are only two bytes in size not three.
If performance seems to be an issue, then I have a few things to adjust in the scheduling:
- I can split the digitalRead() of each button over several scans to allow MIDI processing to happen in between.
- I can switch to the XIAO equivalent of direct PORT IO to try to read all IO pins at the same time. I don’t know what this looks like for the SAMD21 however and it would make it hardware specific, so I’d really rather not do that.
- I can remove the waiting of 1mS. This was in the original USB converter, so I kept it in here too. I ought to measure the free running loop() time to see if it is needed.
Closing Thoughts
In the video I cycle through a few of the programs whilst controlling the synth from a keyboard.
At one point I remove the external audio connection (yes, I should have turned it down first!) to contrast the sound with the internal speaker. Yes, it is a bit “tinny” but it isn’t too bad.
This really is just the very “tip of the iceberg” given the whole range of parameters available that were mentioned in Part 3.
Kevin
#controlChange #midi #programChange #SAM2695 #samd21 #usbHost #xiao
-
XIAO ESP32-C3 MIDI Synthesizer – Part 4
In Part 2 I looked at how to add USB MIDI to the XIAO MIDI Synthesizer and in Part 3 I looked at some of the properties of the SAM2695 synth chip itself. This post combines the two into a relatively simple, but playable, synth.
- Part 1 – Getting started and getting code running.
- Part 2 – Swapping the ESP32-C3 for a SAMD21 to get USB MIDI.
- Part 3 – Taking a deeper look at the SAM2695 itself.
- Part 4 – A USB MIDI Synth Module using the SAMD21 again as a USB MIDI Host.
- Part 5 – A Serial MIDI Synth Module using the original ESP32-C3.
- Part 6 – Pairs the Synth with a XIAO Expansion board to add display and potentiometers.
https://makertube.net/w/kaZT6zPjKUmGQp17J15fMM
Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!
These are the key tutorials for the main concepts used in this project:
If you are new to microcontrollers, see the Getting Started pages.
The Circuit
I’m wanting to plug a USB MIDI keyboard into my XIAO Synth, so I’m going to swap the XIAO ESP32-C3 out once again for a XIAO SAMD21 as described in Part 2. A future post will go back and create a serial MIDI version using the unmodified XIAO Synth.
Recall that a source of 5V power is required, and below I’m just using the 5V USB passthrough from the original XIAO ESP32-C3.
There is one issue to watch out for in this kind of configuration. Depending on how the USB power is provided, there might not be a common ground point between the XIAO’s power and any audio amplification used.
Apparently GND is always passed through many USB charger blocks.
To prevent interference and noise, it may be necessary to ground the USB connection providing power.
The Code
I’m using a combination of the SAMD21 USB Host Library “USB MIDI Converter” example and some GPIO and MIDI handling.
The general thread of the code will be as follows:
loop():
Do any USB host processing (e.g. plug-and-play)
IF USB MIDI messages received THEN
Send to serial MIDI
IF any buttons pressed THEN
Handle button IO
Generate any additional MIDI messages as required
Send to serial MIDIIn particular it should be noted that the MIDI “listening” is one-way only USB to serial MIDI; and that any internal control events that generate MIDI are also only going one way – to serial MIDI.
The buttons will be used to do the following:
- Button 0 and 1: Program Select Up/Down
- Button 2 and 3: Channel Volume Up/Down
A much more sophisticated interface could be developed – e.g. using one of the buttons to change modes for the other buttons, to allow the selection of different things, but for now, this is plenty.
There are several layers to the code to allow this however, so I’ll cover them briefly here.
- Main Loop button IO: Checks for the main H->L, L->H, L->L, H->H events and calls functions for all but the last (buttons are pulled high so H->H means “nothing happening).
- Event functions for Pressed, Released, Hold which call program or volume handling functions as required.
- Program/volume handling functions that update the values and then trigger the appropriate MIDI messages to be sent.
- Functions to send a MIDI Program Change or Control Change message as required.
In the end I’ve only triggered events on button Pressed, so the Release and Hold functions don’t cause any further action to take place, but the model is there for use in the future if required.
Note: as I’m not using the Arduino MIDI Library, I just build PC or CC messages directly and call out to Serial1.Write as shown below.
void midiSendControl (uint8_t cmd, uint8_t d) {
uint8_t buf[3];
buf[0] = MIDI_CC | (MIDI_CHANNEL-1);
buf[1] = cmd;
buf[2] = d;
Serial1.write(buf, 3);
}Simple, but it works. Note PC are only two bytes in size not three.
If performance seems to be an issue, then I have a few things to adjust in the scheduling:
- I can split the digitalRead() of each button over several scans to allow MIDI processing to happen in between.
- I can switch to the XIAO equivalent of direct PORT IO to try to read all IO pins at the same time. I don’t know what this looks like for the SAMD21 however and it would make it hardware specific, so I’d really rather not do that.
- I can remove the waiting of 1mS. This was in the original USB converter, so I kept it in here too. I ought to measure the free running loop() time to see if it is needed.
Closing Thoughts
In the video I cycle through a few of the programs whilst controlling the synth from a keyboard.
At one point I remove the external audio connection (yes, I should have turned it down first!) to contrast the sound with the internal speaker. Yes, it is a bit “tinny” but it isn’t too bad.
This really is just the very “tip of the iceberg” given the whole range of parameters available that were mentioned in Part 3.
Kevin
#controlChange #midi #programChange #SAM2695 #samd21 #usbHost #xiao
-
Time to get to work! 📝💯✨ Genshin Impact character memopads now in stock on my Etsy! Available in 8 different themes. https://etsy.me/3LBjnL0 [All Boosts appreciated! 💕]
#MastoArt #GenshinImpact #genshin #etsy #diluc #kaeya #jean #albedo #xiao #zhongli #tartaglia #childe #hutao #stationery #notepads #memos