I have the following hardware

  1. Raspberry pi 3 B+
  2. 8 Channel relay
  3. DHT11 temperature and humidity sensor
  4. PH-4502C DIY MORE analog PH meter
  5. MCP3008 ATD
  6. Keyestudio TDS Meter V1.0

So far I got everything working using nodejs, I am building an automated hydroponics system and the last part I received was this analog PH probe and module, I have not gotten to the coding part (of the PH, everything else is already fully working) as I have not been able to get all pins connected, note that the module is for arduino.

I have connected all the pins to the corresponding areas on the pi board and the ATD module, all works fine except that whenever I connect the temperature pin the pi won't boot so I am obviously connecting something wrong.

While searching on the internet I could not find other people that have done it as it seems that everyone has issues with that pin, I am attaching an image I created of the current setup.

My question is, has anyone been able to get this module working when using that pin? if so can you provide me with details of how it was connected?

current hydroponics setup

enter image description here

Pins description:

  1. V+ : Power 5v
  2. G : Power ground
  3. G : Signal ground
  4. Po : pH output (analog)
  5. Do : Level signal output (digital)
  6. To : Temperature output (analog? maybe not and that could be the reason is not booting up)

Unfortunately the module information is in Chinese so it is kind of hard to figure this one out.

The module has two leds, when I connect the temperature output pin both leds are red and the pi won't boot, when I remove the temperature output pin only one led is red and the pi boots.

enter image description here


@joan with your mention of the power required for the relay I tested if the issue was insufficient power, I removed everything except for the PH module but the same thing happened. I am also attaching real images of the module when all pins are connected and when the temperature pin is not connected.

Pin not connected: Pin not connected

Pin connected: Pin connected

  • What is the temperature pin? Let's have a clear photo of the connections to the component which cause the failure. Frankly I doubt if the relay could be fully operated from the Pi power supply.
    – joan
    Jan 15, 2020 at 16:35
  • The temperature pin is the pink one that goes to MCP3008 CH2. The relay is fully operational, it controls the pump and the lights without any issues for months. Jan 15, 2020 at 16:40
  • This might help: raspberrypi.stackexchange.com/questions/96653/…
    – tlfong01
    Jan 16, 2020 at 0:57
  • Are you sure your MCP3008 inputs Ch0 and Ch1 are in single ended mode? The comments/chats of the following might help: (1) raspberrypi.stackexchange.com/questions/106761/… (2) raspberrypi.stackexchange.com/questions/106728/…
    – tlfong01
    Jan 16, 2020 at 2:37
  • I mean if your Ch0, Ch1 are in differential mode, and let us say now Ch0 is 1V, Ch1 is 3V, then the input voltage is a negative -2V, which MCP3008 is not loving it, and in this case, there is no guarantee that no nothing won't meltdown or blow up, Rpi might now R.I.P and never boots up again :)
    – tlfong01
    Jan 16, 2020 at 3:21


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