Adafruit Midi Featherwing

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StefanVim
 
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Adafruit Midi Featherwing

Post by StefanVim »

Hello

i did by a pair of Adafruit Midi Featherwing Shields and would like to use them with an ESP32.
The spec f my AZ Delivery ESP32 does have RX/TX on Board and should work: (with Baudrate 31250 - Midi Standart)
UART (TX0, RX0) / RX1, TX1 / RX2, TX2) - Pins 1, 3 / 9, 10 / 16, 17

As i would like to connect the Midi Featherwing to the ESP there are two questions left for me:

1) The Midi Featherwing should work with 3.0V - but the ESP gives 3.3V as Output
Question - Can i connect eachother directly (3.3V and GND) or better use a voltage divider to reduce the output voltage of the ESP32?

2) As i have tested the first Midi Feathering after assembling, it seems to get no input from my Masterkeyboard!?
I did make a little test before and just put 3V and GND from my power supply stastion on the Midi Feather and no RX/TX connections, put the Input LED is not flashing as i pressed a Key on my Masterkeyboard an it is USB-power driven. I also tried a Nord Lead 3 but it did not light up. Tested the Midi cables and Output and both Keyboards and worked fine on a different Midi Device!
Question - Did i blew up the Midi Feather or is it not working without RX/TX connection.

As needed i can upload/add photos of my cicuit.
Thanks in forward for help.

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blnkjns
 
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Re: Adafruit Midi Featherwing

Post by blnkjns »

Midi usually works at a pretty wide range 3-5V no problem. That's because the signal is always optically decoupled. So I doubt you blew it up.
What seems weird is the schematics:
https://cdn-learn.adafruit.com/assets/a ... 1601489240
A blue LED can be lit directly from 3V, as it is about the gate voltage for blue light. But the board includes 2200Ω resistors. That is huge! Even for a red LED on 5V, 220Ω is enough. So that might be the main cause not seeing anything.
Do you have a 32U4 board around? Then you can wire it to the MIDI pins of the featherwing, and load it with a standard Serial Passthrough script to see all data coming in on the MIDI bus in the Serial monitor.

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adafruit_support_mike
 
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Re: Adafruit Midi Featherwing

Post by adafruit_support_mike »

blnkjns wrote:What seems weird is the schematics:
https://cdn-learn.adafruit.com/assets/a ... 1601489240
A blue LED can be lit directly from 3V, as it is about the gate voltage for blue light. But the board includes 2200Ω resistors
Manufacturers have gotten so good at making super-bright LEDs that they’re blinding at 25mA. For basic indication, 1mA or 2mA is just fine.

Many blue and green LEDs light visibly at 100uA or less.

Running blue LEDs from 3.0V can be iffy though. Some have forward voltages of 3.3V to 3.5V, and won’t light at all.

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StefanVim
 
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Re: Adafruit Midi Featherwing

Post by StefanVim »

blnkjns wrote:Midi usually works at a pretty wide range 3-5V no problem. That's because the signal is always optically decoupled. So I doubt you blew it up.
What seems weird is the schematics:
https://cdn-learn.adafruit.com/assets/a ... 1601489240
A blue LED can be lit directly from 3V, as it is about the gate voltage for blue light. But the board includes 2200Ω resistors. That is huge! Even for a red LED on 5V, 220Ω is enough. So that might be the main cause not seeing anything.
Do you have a 32U4 board around? Then you can wire it to the MIDI pins of the featherwing, and load it with a standard Serial Passthrough script to see all data coming in on the MIDI bus in the Serial monitor.
Thanks - blnkjns
The blue Led is lighting up but very poor, and as you mentioned 220Ω is huge.
But...the first board seems like it had a problem - idk - No LED was flashing as data was send, the serial monitor did show up nothing with the correct rate at 31250.
I did wire the direct to UART0 RX/TX and 3.3V and GND from the ESP32 to Board (there are three on the ESP32) => called up with Serial2 in the sketch, but did not work at all.

Code: Select all

#define MIDI_BAUDRATE 31250
#define RXD2 16
#define TXD2 17
I re-ordered another midi featherwing - TADA - and it finally worked.

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StefanVim
 
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Re: Adafruit Midi Featherwing

Post by StefanVim »

adafruit_support_mike wrote:
blnkjns wrote:What seems weird is the schematics:
https://cdn-learn.adafruit.com/assets/a ... 1601489240
A blue LED can be lit directly from 3V, as it is about the gate voltage for blue light. But the board includes 2200Ω resistors
Manufacturers have gotten so good at making super-bright LEDs that they’re blinding at 25mA. For basic indication, 1mA or 2mA is just fine.

Many blue and green LEDs light visibly at 100uA or less.

Running blue LEDs from 3.0V can be iffy though. Some have forward voltages of 3.3V to 3.5V, and won’t light at all.
In my case it was a defectiv board i guess. I did exchange Midifeather board and the new on worked fine.
The voltage of 3.3V from the ESP is enough to power the Midi Feather but the output LED is flashing slightly brighter than the input.

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adafruit_support_mike
 
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Re: Adafruit Midi Featherwing

Post by adafruit_support_mike »

Glad to hear you’ve got things working!

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