MCP23008 2 Channel High Pwr Relay cannot see on i2c

Hardware
1

Recently purchased the above mentioned 2 Channel high power relay for use with a RPI 3. Installed everything per the Github repository for Raspberry Pi, but i2cdetect -r -y 1 does not detect the relay board. I have verified the 12VDC input and have tried various jumper combinations all with no luck. Using the NCD “Screw Terminal Breakout Board with I2C for Raspberry Pi Zero, Pi 2, or Pi 3” for the i2c connection. I have updated /etc/modules and /boot/config.txt and they seem to have the correct info.

Any ideas on what is missing?

2

I get two red led’s for “Power” and “12V”. None of the jumpers are installed, and I read 4.86 VDC across the +5VDC and GND connections on the i2c cable.

3

can you post a picture of your setup.

Thanks

4

IMG_0660
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IMG_0661
IMG_0661.JPG1224×1632 499 KB

Inside the case under the GPIO / i2c board is a RPI-3B

5

everything looks correct.
can you share i2c detect output screenshot?

Thanks

6

pi@gndStation:~ $ i2cdetect -r -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: – -- – -- – -- – -- – -- – -- –
10: – -- – -- – -- – -- – -- – -- – -- – --
20: – -- – -- – -- – -- – -- – -- – -- – --
30: – -- – -- – -- – -- – -- – -- – -- – --
40: – -- – -- – -- – -- – -- – -- – -- – --
50: – -- – -- – -- – -- – -- – -- – -- – --
60: – -- – -- – -- – -- – -- – -- – -- – --
70: – -- – -- – -- – --
pi@gndStation:~ $

7

i guess this needs to come back for a repair and inspection.
You can fill out the RMA over here
https://ncd.io/contact-us/product-returns/

Thanks

8

one more things you can check is the ribbon cable between pi and the i2c shield.
make sure the cable is properly connected and its connected to the black connector on both sides.
if cable is not locked properly it might cause this kind of issue.

this is what i will do
unplug the cable and inspect visually and make sure the ribbon cable is making proper connections with black connectors.

let me know what you find.

Thanks

9

Can you try connecting power to the board to see if that brings the I2C online?

I’ve seen it in chaining devices together that an unpowered device can effect communications.

10

Power is connected to the board. 12 VDC at the terminal connections. Power and 12V lights both on.

Tried adjusting the ribbon cable to see if that helped. Still not detecting board. I will try another ribbon cable and another RPI before returning item for repair.

11

Changed ribbon connectors but it did not help, then changed to another RPI 3 and the relay board was recognized. Must have been something wrong with the RPI. Problem solved.

I was able to turn the relay on and off with " i2cset -y 1 0x20 0x09 0xFF " and "
i2cset -y 1 0x20 0x09 0x00 " but this seems to turn both relays on/off. How do I control each relay individually?

Thanks,
SRF

12

you can use this lib