Complications with SPI configuration

RE: Complications with SPI configuration

Shaney — Tue, 16 Jun 2020 13:50:28 GMT

As an update incase anyone else struggles with the same issue. The problem seem to have been the .dts file. The one for nrf52840 devkit that is included in ncs, nrf52840_pca10056 states the following:

&spi0 {
	compatible = "nordic,nrf-spi";
	/* Cannot be used together with i2c0. */
	status = "okay";
	sck-pin = <27>;
	mosi-pin = <26>;
	miso-pin = <29>;
};

Note the "compatible" filed only states nrf-spi and NOT nrf-spim. This resulted in not all files being generated, thus the error when trying to build .

Adding compatible = "nrf-spim" at spi0,sp1 and spi2 fixed this. The same thing was needed for i2c, changing "nrf-twi" to "nrf-twim".

The bus error can be ignored, it was just me making silly pointer errors.

RE: Complications with SPI configuration

hmolesworth — Fri, 22 May 2020 16:21:07 GMT

Probably not helpful, but I see you mentioned I2C/TWI worked. Just for clarification (in case a reader doesn't know) SPI0 and TWI0 are the same underlying hardware which can be configured as SPI or TWI (but not both at the same time) and therefore share registers and interrupt. Any register left set by TWI0 (or be still in use by TWI0) can cause SPI0 to misbehave. SPI1 and TWI1 ditto; there are not 5 SPI & TWI interfaces, only 3 total.

RE: Complications with SPI configuration

Shaney — Fri, 22 May 2020 10:00:01 GMT

Seems like I managed to get SPI1 and SPI2 working. I will use these for the moment and see if I can figure out why SPIM0 doesn't work. Please close ticket when able.

RE: Complications with SPI configuration

Shaney — Fri, 22 May 2020 09:27:21 GMT

Update, I've seem to be able to successfully bind SPI1, SPI2 and SPIM3. However, as soon as I try to write something I get hard fault.

I init the SPI with the following function:

int32_t get_spi_device(struct device* dev_ptr, char* dev)
{
  printk("Getting device %s...\n", dev);
  dev_ptr  = device_get_binding(dev);
  if(!dev_ptr)
  {
    printk("Error getting %s\n", dev);
    return 1;
  }
  
  return 0;
}

And I have the following settings and buffers:

static struct spi_buf      tx_buf;
static struct spi_buf      rx_buf;

static struct spi_buf_set  tx_bufs = {
  .buffers = &tx_buf,
  .count = 1,
};

static struct spi_buf_set  rx_bufs = {
  .buffers = &rx_buf,
  .count = 1,
};

static const struct spi_config spi_cfg = {
	.operation = SPI_WORD_SET(8) | SPI_TRANSFER_MSB |
		     SPI_MODE_CPOL | SPI_MODE_CPHA,
	.frequency = 1000000,
	.slave = 0,
};

And finally I try to write on the bus using:

spi_write(spi1, &spi_cfg, &tx_bufs);

Once I try writing with this function the device hard faults. I've been trying to debug to see where the error occurs but I only reach static inline int z_impl_spi_transceive before I get error "Not enough hardware instruction breakpoints"

RE: Complications with SPI configuration

Shaney — Fri, 22 May 2020 08:43:05 GMT

Hi,

Yeah I double checked the pins and have reverted to the default pins set in the .dts file:

&spi0 {
	compatible = "nordic,nrf-spi";
        status = "okay";
	sck-pin = <27>;
	mosi-pin = <26>;
	miso-pin = <29>;
};

&spi1 {
	compatible = "nordic,nrf-spi";
	status = "okay";
	sck-pin = <31>;
	mosi-pin = <30>;
	miso-pin = <40>;
};

&spi2 {
	compatible = "nordic,nrf-spi";
	status = "okay";
	sck-pin = <42>;
	mosi-pin = <43>;
	miso-pin = <44>;
};

&spi3 {
	status = "okay";
	sck-pin = <47>;
	miso-pin = <46>;
	mosi-pin = <45>;
};

However, the issue still persists.

[quote userid="18935" url="~/f/nordic-q-a/61692/complications-with-spi-configuration/251188"]# CONFIG_SPI_0 is not set[/quote]

This is intentional for now as the build fails if I enable this.

[quote userid="18935" url="~/f/nordic-q-a/61692/complications-with-spi-configuration/251188"]# CONFIG_SPI_1_NRF_SPIM is not set[/quote][quote userid="18935" url="~/f/nordic-q-a/61692/complications-with-spi-configuration/251188"]# CONFIG_SPI_2_NRF_SPIM is not set[/quote]

This is also intentional because configuring SPI1 & SPi2 as the old deprecated way is the only way I've manage to get it working somewhat as expected.

RE: Complications with SPI configuration

Turbo J — Fri, 22 May 2020 08:35:15 GMT

I see some problems:

Spi0:

# CONFIG_SPI_0 is not set

You need to enable SPI 0.

Also check the following:

# CONFIG_SPI_1_NRF_SPIM is not set

# CONFIG_SPI_2_NRF_SPIM is not set

Spi1:

sck-pin = <0>;
mosi-pin = <1>;

P0.0 and P0.1 are the LF crystal pins and should never be used as anything else on the DK.

SPIM3 has serious hardware bugs on the NRF52840 - see errata sheet. No idea whether the software workaround is properly implemented in zephyr - my guess would be: No.