NRF52840 SPIM3

Question

Hi,

I am using the 2 NRF52840 boards, rev 1. I am using SDK 15.2. The first board is running the NRFX_SPIM example. The second board is running the SPIS example. The rx_delay is set to 0x02.

When I configured the SPIM to run at 4MHz. The SPIM and SPIS sometimes get the correct message. and sometimes get data value of all F's.

When I configured the SPIM to run at 32MHz. The SPIM and SPIS received data is always incorrect.

Any ideas? Has anyone tried using the NRFX_SPIM and SPIS example projects together?

Thanks,

SPIM configured to run at 4MHz result. Below is the result from the SPIM.

0> <info> app: Transfer completed.
0> <info> app: Received:
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF |.....
0> <info> app: Transfer completed.
0> <info> app: Received:
0> <info> app: FF 4E 6F 72 64 69 63 31|.Nordic1
0> <info> app: 32 33 34 35 36 37 38 39|23456789
0> <info> app: 30 31 32 33 34 35 36 37|01234567
0> <info> app: 38 39 30 31 32 33 34 35|89012345
0> <info> app: 36 37 38 39 30 |67890
0> <info> app: Transfer completed.
0> <info> app: Received:
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF |.....
0> <info> app: Transfer completed.
0> <info> app: Received:
0> <info> app: FF 4E 6F 72 64 69 63 31|.Nordic1
0> <info> app: 32 33 34 35 36 37 38 39|23456789
0> <info> app: 30 31 32 33 34 35 36 37|01234567
0> <info> app: 38 39 30 31 32 33 34 35|89012345
0> <info> app: 36 37 38 39 30 |67890

Below is the result of the SPIM when configured to run at 32MHz.

0> <info> app: Transfer completed.
0> <info> app: Received:
0> <info> app: FF FF FF DF E5 C9 D3 C7|........
0> <info> app: 63 64 67 68 6A 6C 6E 38|cdghjln8
0> <info> app: 39 30 31 32 33 FF FF FF|90123...
0> <info> app: FF FF B9 B0 B1 B2 B3 B4|........
0> <info> app: B5 B6 B7 B8 B9 |.....
0> <info> app: Transfer completed.
0> <info> app: Received:
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF FF FF FF|........
0> <info> app: FF FF FF FF FF |.....

Below is the result of SPIS when configured to run at 32MHz.

Transfer completed

hmolesworth · Accepted Answer

I tried with out-of-box software on 2 x pca10056 nRF52 DKs SDK 15.2.0 and get good operation at 8MHz and 16MHz provided the hardware CS is disabled; the issue seems to be too short a setup time between /CS and SCK going active. It partially works at 32MHz, but every other packet gets slightly damaged. SPIM: 
 // This is working reliably at 16MHz, SPIM to SPIS both directions
// Only change is to SPIM, but SPIS works better in release mode
 nrfx_spim_config_t spi_config = NRFX_SPIM_DEFAULT_CONFIG;
 spi_config.frequency = NRF_SPIM_FREQ_16M; // <======== !
 spi_config.ss_pin = NRFX_SPIM_SS_PIN;
 spi_config.miso_pin = NRFX_SPIM_MISO_PIN;
 spi_config.mosi_pin = NRFX_SPIM_MOSI_PIN;
 spi_config.sck_pin = NRFX_SPIM_SCK_PIN;
 spi_config.dcx_pin = NRFX_SPIM_DCX_PIN;
 spi_config.use_hw_ss = false; //true; // <======== !
 spi_config.ss_active_high = false;
 spi_config.mode = NRF_SPIM_MODE_0;
 spi_config.rx_delay = 0x02;
 spi_config.ss_duration = 0x02;

 APP_ERROR_CHECK(nrfx_spim_init(&spi, &spi_config, spim_event_handler, NULL));

 // High power output pins
 nrf_gpio_cfg(NRFX_SPIM_SS_PIN,
 NRF_GPIO_PIN_DIR_OUTPUT,
 NRF_GPIO_PIN_INPUT_DISCONNECT,
 NRF_GPIO_PIN_NOPULL,
 NRF_GPIO_PIN_H0H1, // Require High Drive high/low level
 NRF_GPIO_PIN_NOSENSE);

 // High power output pins
 nrf_gpio_cfg(NRFX_SPIM_MOSI_PIN,
 NRF_GPIO_PIN_DIR_OUTPUT,
 NRF_GPIO_PIN_INPUT_DISCONNECT,
 NRF_GPIO_PIN_NOPULL,
 NRF_GPIO_PIN_H0H1, // Require High Drive high/low level
 NRF_GPIO_PIN_NOSENSE);

 // High power output pins
 nrf_gpio_cfg(NRFX_SPIM_SCK_PIN,
 NRF_GPIO_PIN_DIR_OUTPUT,
 NRF_GPIO_PIN_INPUT_DISCONNECT,
 NRF_GPIO_PIN_NOPULL,
 NRF_GPIO_PIN_H0H1, // Require High Drive high/low level
 NRF_GPIO_PIN_NOSENSE);

 NRF_LOG_INFO("NRFX SPIM example started."); 
 Note SPIS works better if compiled in Release build or with better optimisation, SPIS: 
 nrf_drv_spis_config_t spis_config = NRF_DRV_SPIS_DEFAULT_CONFIG;
 spis_config.csn_pin = APP_SPIS_CS_PIN;
 spis_config.miso_pin = APP_SPIS_MISO_PIN;
 spis_config.mosi_pin = APP_SPIS_MOSI_PIN;
 spis_config.sck_pin = APP_SPIS_SCK_PIN;
 spis_config.mode = NRF_SPIS_MODE_0;

 APP_ERROR_CHECK(nrf_drv_spis_init(&spis, &spis_config, spis_event_handler));

 // High power output pins
 nrf_gpio_cfg(APP_SPIS_MISO_PIN,
 NRF_GPIO_PIN_DIR_OUTPUT,
 NRF_GPIO_PIN_INPUT_DISCONNECT,
 NRF_GPIO_PIN_NOPULL,
 NRF_GPIO_PIN_H0H1, // Require High Drive high/low level
 NRF_GPIO_PIN_NOSENSE);

hmolesworth · Answer

That looks suspiciously like low drive issues, especially since traversing a significant number of mm from one board to another. I think the examples do not set high drive, so maybe try something like this after initialisation on all SCK CS and MOSI pins (6 pins in all): 
 nrf_gpio_cfg(SCK_1_PIN,
 NRF_GPIO_PIN_DIR_OUTPUT,
 NRF_GPIO_PIN_INPUT_DISCONNECT,
 NRF_GPIO_PIN_NOPULL,
 NRF_GPIO_PIN_H0H1, // Require High Drive low & high levels
 NRF_GPIO_PIN_NOSENSE);

hmolesworth · Answer

On the nRF52DK pca10056 pin P0.06 - SCK in this case - is driving D17 and TxD; D17 may be unconnected but TxD is connected to MUX U5 and hence potentially to IMCU_RxD on the J-Link interface ATSAM3U. There is a cuttable link .SBS2 to remove that loading, which at 16MHz or 32MHz will be significant.

NRF52840 SPIM3

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