SPIM3 reads fail when SoftDevice enabled

RE: SPIM3 reads fail when SoftDevice enabled

csulz — Wed, 02 Sep 2020 16:54:02 GMT

There are four scenarios on two variables: Jtag Debug board (nrf52840-DK) running program with SEGGER plugged in or not, and softdevice enabled/disabled.

Debug board Connected - SPIM3 Always works regardless of softdevice

Debug board disconnected - Softdevice disabled - SPIM3 works.

Debug board disconnected - Softdevice enabled - No clock to SPIM3.

RE: SPIM3 reads fail when SoftDevice enabled

Kenneth — Wed, 02 Sep 2020 07:29:17 GMT

And the problem only occurs when softdevice is enabled?

I don't really have any other suggestion than to try and fail a bit, maybe even add SPIM3 to a simple example to check if that works.

Kenneth

RE: SPIM3 reads fail when SoftDevice enabled

csulz — Tue, 01 Sep 2020 21:46:13 GMT

I tried this, there is no difference. Made both the nrfx_spim_xfer_desc_t struct and nrfx_spim_config_t (for this spim) global and there is no difference.

RE: SPIM3 reads fail when SoftDevice enabled

Kenneth — Tue, 01 Sep 2020 08:43:53 GMT

Have you tried to disconnect the external chip, just to verify that SCK is not held low?

Can you try to make nrfx_spim_xfer_desc_t desc and nrfx_spim_config_t spim_config global or static, in case the compiler is doing some optimization here?

Kenneth

RE: SPIM3 reads fail when SoftDevice enabled

csulz — Mon, 31 Aug 2020 17:25:43 GMT

Are you speaking about Errata 198? I will try the suggested solution although I am not sure if that describes my problem. Verified by the oscilloscope the clock does not pulse when the SPIM is supposed to be sending/receiving. I don't see ANY transmit data, let alone incorrect ones.

RE: SPIM3 reads fail when SoftDevice enabled

csulz — Mon, 31 Aug 2020 17:19:16 GMT

Yes, sorry there is a while loop waiting for the spim_done flag which is set in the spim_event_handler

while (!spim_done) {
__WFE();
}

RE: SPIM3 reads fail when SoftDevice enabled

Turbo J — Mon, 31 Aug 2020 09:36:38 GMT

[quote userid="79354" url="~/f/nordic-q-a/65263/spim3-reads-fail-when-softdevice-enabled"]I am honestly stumped as to what the SD enable has to do with the SPIM transfer. Any help is appreciated.[/quote]

Have look into the errata sheet!

SPIM3 has a nasty DMA bug. The SD probably just makes it more likely to trigger.

Basically you need to reseve one (or two, depending on usage scenario) complete RAM blocks for SPIM3, so that there is no CPU data access in that block during DMA.

Together with SD this is a non-trivial linker script/settings modification. The example workaround in the SDK does not work with SD enabled.

RE: SPIM3 reads fail when SoftDevice enabled

Kenneth — Mon, 31 Aug 2020 09:20:58 GMT

I assume you code is somewhat like this (added wait for spim_done):

uint8_t tx[4];
memset(tx, 0, sizeof(tx));

tx[0] = W25_JEDEC_ID; // request manufacturing id

nrf_gpio_pin_set(PINNUM_nCSF0); // ensure Flash 0 is not selected
nrf_gpio_pin_set(PINNUM_nCSF1); // ensure Flash 1 is not selected
nrf_gpio_pin_clear(PINNUM_nCSF0); // select Flash 0

nrfx_spim_xfer_desc_t desc = {
.p_tx_buffer = tx,
.tx_length = 4,
.p_rx_buffer = rx,
.rx_length = 4
};

uint32_t ret;

spim_done = false;

ret = nrfx_spim_xfer(&fastspim, &desc, 0);
APP_ERROR_CHECK(ret);

while(!spim_done)
  ;

nrf_gpio_pin_set(PINNUM_nCSF0); // not select Flash 0
nrf_gpio_pin_set(PINNUM_nCSF0); // ensure Flash 0 is not selected
nrf_gpio_pin_set(PINNUM_nCSF1); // ensure Flash 1 is not selected

//rx buffer is then read and compared against expected

RE: SPIM3 reads fail when SoftDevice enabled

csulz — Thu, 27 Aug 2020 19:27:18 GMT

I took your advice and brought out the oscilloscope. Triggering on the chip select, with softdevice OFF I can see the clock pulses and data as you would expect. With Softdevice ON I can see the chip select asserted but there is no clock pulses present.

These pins are initialized like so:

#define PINNUM_F_MOSI 17

#define PINNUM_F_MISO 19

#define PINNUM_F_SCLK 15

...

nrf_gpio_cfg_output(PINNUM_F_MOSI);
nrf_gpio_cfg_input (PINNUM_F_MISO, NRF_GPIO_PIN_NOPULL);
nrf_gpio_cfg_output(PINNUM_F_SCLK);

RE: SPIM3 reads fail when SoftDevice enabled

csulz — Thu, 27 Aug 2020 17:10:25 GMT

Also to confuse matters more the program works normally when our board is connected to the nRF52840-DK J-link debugger. So when debugging (using SEGGER) everything works fine but when the device is running on the actual hardware it does not. But when the softdevice code is not included the flash read works correctly.

RE: SPIM3 reads fail when SoftDevice enabled

Kenneth — Thu, 27 Aug 2020 12:34:01 GMT

I recommend a logic analyzer trace here, to compare with and without softdevice enabled. Just to look at the serial transaction (e.g. is the pins correct, is the MISO and MOSI correct, number of bytes etc) between working and failing.

Kenneth