1 year, 3 months ago.

Using Nucleo-L432KC to open and close a 4-way relay board

Hi

I'm using a Nucleo-L432KC to send signals to a 4-way relay board from Hui Ke (HK3FF-DC5V-SHG).

The relays work correctly when they are connected to output pins A6 and A7. The same relays do not work when I use A4 and A5 as digital outputs. Is there a reason why pins A4 and A5 should be avoided when on/off signals are supplied to a relay board?

Kind regards

Koos

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2 Answers

1 year, 3 months ago.

Koos -

The NUCLEO-L432KC board has limitations on using A4 and A5 that are causing your problem. SB16 and SB18 tie pin pairs D5 (PB6) +A5 (PA6) and D4 (PB7) +A4 (PA5) together to provide Arduino-compatible I2C support. These two solder bridges are ON by default. A4 (PA5) and A5 (PA6) can only be used as "input floating" with the solder bridges ON. Remove SB16 and SB18 to allow you to use A4 and A5 as digital outputs.

Refer to the user manual UM1956 for the Nucleo32 boards for the details.

Dear Mr Roth,

Thank you very much for your input.

Kind regards

Koos

posted by Koos van der Wat 05 Jul 2018
1 year, 3 months ago.

Hello Koos,

Can you post your code so that we can see what wrong with it? It is possible that A6 and A7 are PWM pins while A5 and A4 are not.

Please let me know if you have any questions!

- Peter, team Mbed

If this solved your question, please make sure to click the "Thanks" link below!

Dear Peter,

Thant you very much.

Kind regards

Koos

posted by Koos van der Wat 05 Jul 2018