SPI communication via DMA in background using ppi and a timer

[Constantin]

Hi,

I've just realized the project from 

https://github.com/Martinsbl/nrf5-mpu-examples/tree/master/nrf52-mpu-easydma-using-gpiote-and-registers

And it is working quiet well. Now I need something similar for SPI communication. I've tried it with the registers but so far no success since in the new SDK there is no CS entry for the register:

typedef struct {

  __IOM uint32_t  SCK;                          /*!< (@ 0x00000000) Pin select for SCK                                         */

  __IOM uint32_t  MOSI;                         /*!< (@ 0x00000004) Pin select for MOSI signal                                 */

  __IOM uint32_t  MISO;                         /*!< (@ 0x00000008) Pin select for MISO signal                                 */

} SPIM_PSEL_Type;                               /*!< Size = 12 (0xc)                                                           */

So is there any official or unofficial example for using the NRF_SPIM0->... either via driver or directly via the registers?

So far in the TWIM example it is not possible to switch between DMA and direct write without uninitialization of the SPI.

Best regards,

C.W.

[CheMax]

Hi,

I think. you can try find some code examples in this topic : ads1299-reading-register_spi_nrf52832 or /nordic-q-a/37497/rare-counter-error

Best regards,

Max

[Vidar Berg]

Hi,

Have you tried to have a look at the SDK example: SPI Master Example. The driver documentation can be found here: SPIM.

Constantin said:

So far in the TWIM example it is not possible to switch between DMA and direct write without uninitialization of the SPI.

The TWIM0 and SPIM0 are shared so they cannot be used at the same time. Maybe you can use another TWIM or SPIM instance instead? 

[Constantin]

Sorry no. The SPI Master Example is the lowest performance ever. I would like to have an Example with ArrayList mode which runs without CPU usage like the Example of Martin.

I did not mean to use TWIM and SPIM at the same time but SPIM in Arraylist mode and normal SPIM. It is not working when the SPIM is in Arraylist mode I cannot write to it although no communication is going. I have to uninit it and init again without Arraylist.

[Vidar Berg]

We don't have an example for this, but the driver documentation which I linked to earlier explains how you can enable list mode (NRF_DRV_SPI_FLAG_TX_POSTINC) and start transfers through PPI.