Custom Synchronous Communication Protocol

RE: Custom Synchronous Communication Protocol

Jared — Mon, 04 May 2020 12:59:53 GMT

I'm sorry for the misunderstanding. GPIOTE task is not appropriate for this as it will only do simple tasks. To be honest, I'm not sure if this is as trivial as I first thought 🙂 An alternative could be to use the PWM peripheral to drive the data line but i'm not sure if this is a good solution either as it might be a bit complicated to implement. If SPI is an alternative then I would suggest going for that one..

RE: Custom Synchronous Communication Protocol

Sava — Thu, 30 Apr 2020 18:29:45 GMT

Hi Jared,

Sorry for my poor explanation of the problem. Each bit on the tx data line has to be set after the bit clock goes low to high as shown in the picture below. As stated, the clock is generated by another chip therefore using the spim library wouldn't be possible.

Thanks,

Sava

RE: Custom Synchronous Communication Protocol

Jared — Thu, 30 Apr 2020 11:06:25 GMT

Hi,

[quote user="Sava"]The clock signal is generated by the nfc chip. [/quote]

aha, I see..

Yes, you can start the SPI task TASKS_START on a low to high transition by using the rising edge GPIOTE event.

regards

Jared

RE: Custom Synchronous Communication Protocol

Sava — Wed, 29 Apr 2020 13:15:18 GMT

Hi Jared,

The clock signal is generated by the nfc chip. Can I use GPIOTE and PPI to synchronize the data line with the clock low-to-high transition?

RE: Custom Synchronous Communication Protocol

Jared — Wed, 29 Apr 2020 12:35:54 GMT

Hi,

You could produce the CLK signal with the PWM peripheral. You could then trigger the task start of the PWM by using PPI + GPIOTE and trigger it on a IN event on tx enable pin. See the GPIOTE example on how to use GPIOTE + PPI.

regards

Jared