TWI on alternate pins

RE: TWI on alternate pins

Alexander Schrab — Wed, 15 Jun 2016 12:28:14 GMT

Ok, so I cracked it. I hadn't shifted the address >> 1 correctly. Why I ever got an answer is beyond me, but now it works reliably over pins.

RE: TWI on alternate pins

Alexander Schrab — Wed, 15 Jun 2016 06:14:05 GMT

I still cannot make this work reliably, it feels like it works sometimes (I get success back from tx/rx) but I cannot make it work always, either it fails when I switch pin or rearrange the code slightly.

What is involved in making i2c work through this api? Timing? Pin configuration? Anything besides what is in the code snipped that I need to consider? I am sure nothing else is using those pins...

RE: TWI on alternate pins

MartinBL — Fri, 10 Jun 2016 14:11:06 GMT

The TWI's SDA and SCL lines can be mapped to any pin you like. Using pin 2 and 3 should not be a problem. Pin 26 and 27 are just examples pins defined in our SDK to be compatible with Arduino and mbed shields which often has TWI lines on those pins. If the exact same code works when you use pin 26 and 27, but not when you use 2 and 3 there must be something wrong with the hardware. Or maybe you are accidentally using the pins for something else in your code? Pin 2 and 3 are e.g. two of the analog pins often used by the ADC.