nRF52832: 3 x SPI Master instances

[jinvers]

Hello,

In an existing device using the nRF52832 I have 2 SPI Master instances. Please, may you confirm that is possible to create a third SPI Master instance?

By the way, for optimizing pinout I would like to share the CLK,MOSI snd MISO signals and use different CS pins to select between the three different devices. Do you see any problem with this scenario?

Regards,

Joel

[Kenneth]

Hello,

The nRF52832 have up to 3 SPIM instances:
https://docs.nordicsemi.com/bundle/ps_nrf52832/page/peripheral_interface.html#d932e91 

Note however that these instances overlap with other types of peripherals (e.g. twi, uart), so that is something you may need to consider if you are using any those already.

It's possible to share CLK, MISO and MOSI signales between several slaves, as long as only one of the slaves is selected by the Chip Select (CS) pin at any time. In such case the most common is to use only one SPIM instance, and then only change the CS# pin between transfer.

Kenenth

[jinvers]

Hello Kenneth,

Thank you for your reply.

Do you have any example code? In my case I would use the SDK 17.1.0 and the Segger IDE.

Regards,

Joel

[Kenneth]

Just quickly looking at https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/spi_master_example.html

In main() I would have changed to:
spi_config.ss_pin   = NRF_DRV_SPI_PIN_NOT_USED;

Then each time you want to write to a spi slave device you simply do something like:

// spi device #1

csn_pin1 = 0;
nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length))
csn_pin1 = 1;

// spi device #2

csn_pin2 = 0;
nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length))
csn_pin2 = 1;

and so on.

Kenneth

[jinvers]

Thank you Kenneth.

Regards,

Joel