💾 Archived View for librehacker.com › gemlog › tech › 20210714-0.gmi captured on 2024-05-26 at 15:30:34. Gemini links have been rewritten to link to archived content
⬅️ Previous capture (2024-05-10)
-=-=-=-=-=-=-
I was able to set the GPIOs to output mode and to set the GPIOA pins to pattern 10101010. Here is me testing it with a voltmeter:
Arduino Nano driving an MCP23S17 GPIO Expander module
It turns out that I was sending SPI signals correctly, but that I had make a mistake in the register data I was sending. The IODIRA register, which sets the pins to input or output, requires a 1 for input and a 0 for output. I had assumed it was 1 for output.
MCP23S17 data sheet snippet: IODIR
I have found that if a MC periphal is not doing what is expected, the problem generally comes down to one of five issues:
That's great that you got it figured out! By the way, the link to the data sheet just gives me a permanent failure when I click it.
Just tested again this morning. It works now.