nrf52 PPI+EasyDMA using timer and SPI

[Vishnu Pradeep]

Hi,

I am using nrf52832 for my application. The application share same SPI module for two sensors(with sensors are selected using two chip select pins). Is it possible to implement PPI channel between a timer and this SPI module so that I can collect data from both the sensors every 1ms? I would like to collect the SPI data using EasyDMA and send these data through BLE every 50ms. how can it be achieved with the help of PPI and EasyDMA?

[Vishnu Pradeep]

Hi, Is it possible to assign the same SPI pins for two SPI modules of nrf?

[Wojtek]

I don't think so, but why would you want to do that...?

[Vishnu Pradeep]

I thought I would initiate SPI transfer for both the modules using same Timer compare event by connecting both the SPI tx task to the timer event.

[Wojtek]

Ah, so different pins and modules, but same PPI? Yes, it is possible. Fork register can be used for that

NRF_PPI->CH[PPI_CHANNEL].EEP = NRF_TIMER3->EVENTS_COMPARE[0];
NRF_PPI->CH[PPI_CHANNEL].TEP = NRF_SPIM0->TASKS_START;
NRF_PPI->CH[PPI_CHANNEL].FORK = NRF_SPIM1->TASKS_START;
NRF_PPI->CHENSET = (1 << PPI_CHANNEL);

[Vishnu Pradeep]

Same pins and different modules. Suppose if I use pins 2,3,4 as MOSI,MISO and CLK. Can I assign the same pin for SPI0 and SPI1?