SPI VS UART For Minimal Data Transfer & Sleep

[snoopy20]

Hi devs,

I'm using the NRF52810 to occasionally reprogram a PIC16F15 series chip on boot using SPI. It's working well.

Once the NRF main routine is entered I periodically need to transfer a single byte to the PIC (TX only no confirm) using a timer and have a choice between SPI or UART.

The PIC16F supports both but UART has an advantage in that it's so slow I can sleep the PIC CPU, wake-up on INT and still capture the byte. SPI always needs the PIC clock running.

As such I'm leaning towards UART. My question is when UART EasyDMA is triggered by a timer via PPI will the sd_sleep routine get in the way? I also read UART RX takes 2.3mA of power which I certainly want to avoid, but I assume it can be shut off for TX only. Is there any other aspects I should be aware off before implementing?

Essentially what I'd like to do is for PPI to enable UART, transfer, then disable UART. If I can't enable/disable without CPU intervention and it adds quite a current penalty then the merits over sticking with SPI are less apparent.

Thanks,

Andrew

[snoopy20]

For some reason I can't close based on your answer, but yes I'm sticking with SPI. There is another advantage, the slave device (in my case a PIC16) can use the pin clk and fully Sleep until the buffer is read.