Basic digital I/O issue


I'm currently trying a basic setup to test digital IO pins CH1 - CH7 and I cannot make this basic functionality work. I am connecting the digital IO as per instruction (page 5):

And I run the following simple test code:

#include <Indio.h>
#include <Wire.h>

void setup() {
  Indio.digitalMode(1, OUTPUT);
  Indio.digitalMode(2, OUTPUT);
  Indio.digitalMode(3, OUTPUT);
  Indio.digitalMode(4, OUTPUT);
  Indio.digitalMode(5, OUTPUT);
  Indio.digitalMode(6, OUTPUT);
  Indio.digitalMode(7, OUTPUT);
  Indio.digitalMode(8, OUTPUT);

void loop() {
  Indio.digitalWrite(1, HIGH);
  Indio.digitalWrite(2, HIGH);
  Indio.digitalWrite(3, HIGH);
  SerialUSB.println("Writing HIGH to CH1");
  Indio.digitalWrite(1, LOW);
  Indio.digitalWrite(2, LOW);
  Indio.digitalWrite(3, LOW);
  SerialUSB.println("Writing LOW to CH1");

I don't observe however any Voltage changes on the pins (CH1, CH2 and CH3). I can see that messages are printed in the console, so the program is executing fine. I have a stable 12V, 8A power supply that is powering my Industruino. Whatismore the Voltage on pins is different (and stable) it is 5.3, 0, 5.4 on CH1, CH2 and CH3 respectively - which is odd, I'm expecting it to be 12V just like my power supply. Is my Industruino broken or could I be doing something wrong? Appreciate your help.



Maciej Poszywak
Maciej Poszywak
| 0 0 0
Asked on 8/22/21, 8:24 PM

Hi, sorry to hear about your issue. The program is indeed correct and you should find 12V on CH1-2-3, it works on my INDIO. Have you connected your PSU 12V to V+ and GND to V- on the INDIO? When you look through the casing, you should see 3 green LEDs on the baseboard, they should all be ON. If not clearly visible, you can remove the casing to check. Also check they are ON when the USB cable is not connected. If further problems, please contact us on

on 8/24/21, 6:45 AM

As for the connections, I have "V+" and "V-" on the PSU, I connected them to "VIN" and "GND" on the INDIO respectively, there is a firm 12V there. As for the LEDs, I can see only one being lit - the one on the bottom of the upper board (the board where the display is located). When I unscrewed the upper board I could read the label near the diode "HL1". In fact I couldn't really see any other diode there except this one. It is also lit regardless if I have the USB connected or not. I have D21G REV1.7 (label on the upper board) and REV2.2 (label on the lowev board). 

Maciej Poszywak
Maciej Poszywak
| 0 0 0
Answered on 8/25/21, 7:35 AM

hi, if your Industruino says VIN and GND then you have a PROTO, not an INDIO. for PROTO, the pins behave a standard Arduino, see

on 8/25/21, 8:28 AM

That helped, it works fine now. Thanks a lot Tom!

Maciej Poszywak
on 8/25/21, 9:20 AM

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Asked: 8/22/21, 8:24 PM
Seen: 114 times
Last updated: 8/25/21, 7:35 AM