Managing multiple SPI and TWI peripherals

[dawsonc]

Hello,

I'm working on an application where we have a number of sensors and a radio that each require a connection to the nRF52. Specifically, 4 of these peripherals need a SPI connection to the nRF52 and one needs an I2C connection. We can put two of the peripherals on the same SPI bus with very little issue, since the two peripherals operate at strictly different times. The other 2 SPI peripherals need to be checked at approximately 1 kHz and 100 Hz, respectively (we need to read data out of a buffer before it gets overwritten). The I2C peripheral only needs to be referenced at a rate of < 1 Hz.

I understand that the nRF52 cannot use SPI0 and TWI0 at the same time. My main question is this: is it feasible (and if it is, how quickly can the nRF52 accomplish this) to switch between using SPI0 and TWI0 (i.e. de-initialize one peripheral and re-initialize another) so that we could place the two peripherals on separate SPI buses? Or would it be better to figure out how to time multiplex the two peripherals on the same SPI bus?

[Nguyen Hoan Hoang]

For the critical one use SPI2. It is not shared with TWI. You can of course put multiple SPI devices together and use manual chip select. It would be faster than switching between TWI and SPI.

There is an open source library that take cares of this sort of thing for you. It does not have much documentations but has few examples that show how to use. Follow this blog to setup the environment. The blog also has links to source code.