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.

29.9	Hz Frame
65535	bytes per frame
1959496.5	byte per second
600	us frame gap

29.9	Hz Frame
65535	bytes per frame
1959496.5	byte per second
600	us frame gap

NRF52840 SPIM3

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