SPI communication between Stm32 nucleo l4r5zi-p and nordic nRF 52840 DK board

[YASH.97]

I used stm32 as master and nordic board as a slave , in stm32 i used spi2 where my configuration is , baud rate is 4MBits/s , clock polarity high , clock phase 1 edge and in nordic board i used spis slave example from SDK (nRF5_SDK_17.0.2_d674dde)  , so when i send data , in first time i got garbage data in both side then i got correct data unti i do not power off the smt32 . When i remove usb cable of master and again connect i got garbage in first time transmission. Only power on and off condition i got garbage in first time , I configure master in that way that when i push the button then data will sent and receive  like that every time we push the button we get the data on both side but on first time got garbage data . Why?

[Jared]

Hi,

You need to debug this more, you need to check what is actually sent on MISO and MOSI during the first transmission by probing the data lines. How does it look? 

regards

Jared 

[YASH.97]

I checked on oscilloscope so i found that on mosi line no data is available and on miso line i saw garbage value .

[Jared]

Hi,

Are you using the example unmodified? Could you specify what you mean by garbage value, is it a specific character or random character every time?

regards

Jared 

[YASH.97]

i modified nordic code like -:

while(1)

{

     memset(m_rx_buf,0,sizeof(m_rx_buf));
    spis_xfer_done = false;
    APP_ERROR_CHECK(nrf_drv_spis_buffers_set(&spis, NULL, 0, m_rx_buf, sizeof(m_rx_buf)));
    while (!spis_xfer_done)
   {
      __WFE();
   }
   NRF_LOG_INFO("%s",(uint32_t)m_rx_buf);
   APP_ERROR_CHECK(nrf_drv_spis_buffers_set(&spis, m_rx_buf, sizeof(m_rx_buf), NULL, 0));
   NRF_LOG_FLUSH();
   bsp_board_led_invert(BSP_BOARD_LED_0);

}

and i got randon character.

[Jared]

What if you use the unmodified example?

[YASH.97]

only data received by slave, data not transmit to master mean when we use unmodified example there is only half duplex communication happen.

[Jared]

Hi,

The unmodified example should send a "Nordic" string. Can you probe directly on the MISO line and check if you can see any characters being sent? Are you using a DK? The issue might be how you handle the data on the Master side.

regards

Jared

[YASH.97]

yes I'm using nrf 52840 dk board , and other thing is that master side everything is ok because before Nordic board I completed two board communication using two stm32 board now only slave is changed which is nordic board.