3 SPI slave sharing the same SCK, MISO and MOSI.

[Ted]

I use the nRF52840 MCU and SDK 16 with S140 softdevice. I want to use spi interface to control 3 SPI slave. They share the same SCK, MISO and MOSI. I use 3 chip select pis to select the slave. How to change the chip select pin to control the slave? Can anyone guide me how to do it? Do you have any example to provide me?

[Jørgen Holmefjord]

Hi,

There is no HW control of SS/CSN pin in the SPI/SPIM peripherals (except in High-speed SPIM3 instance). The driver has support for controlling a single SS pin from the application. If you need to control more SS pins, you need to do that from your application. Set the SS pin to NRF_DRV_SPI_PIN_NOT_USED/NRFX_SPI_PIN_NOT_USED/NRFX_SPIM_PIN_NOT_USED when initializing the SPI driver, configure all SS pins as output using nrf_gpio_cfg_output(pin_number), and control the pins using nrf_gpio_pin_set(pin_number)/rf_gpio_pin_clear(pin_number) before and after each transfer.

Best regards,
Jørgen

[Ted]

@Jorgen,

Thanks for your reply. . I'll try it.