ask about this BUG the SPIM: An additional byte is clocked out when RXD.MAXCNT = 1

[victor_CHINA]

Dear nordic employee

when I use the spim to send 1 byte address to read it's value(4 bytes)

nrf_drv_spi_transfer(&spi,headerBuffer,(uint8_t)headerLength,readBuffer,(uint8_t)readlength);    headerLength=1;      readlength=4;

I get the problem like the title says

I try to solve it

so I DO like this ：spi_pan58_workaround_sdk12.zip（which Referred here）

but when I try to read 4byte data（with 1 byte address write），the result is 00 00 00 00（it should be 12 02 33 44 ）

where is wrong ？

thank you！

[Sigurd]

Hi,

• What SDK version are you using ?
• What was the result of the read operation before you added the workaround ? Did you get 00 00 00 00 before you added the workaround also? or did you get something else?

[Sigurd]

It should be shown in the main.c file in the spi_pan58_workaround_sdk12.zip in the post you linked to. Please take a look at that file.

I.e.

Add this with the other defines:

// ### Workaround Section Start ###
#include "nrf_drv_ppi.h"
#include "nrf_drv_gpiote.h"
// ### Workaround Section End   ###

// ### Workaround Section Start ###
static nrf_ppi_channel_t ppi_channel;
//Dummy handler
void in_pin_handler( nrf_drv_gpiote_pin_t pin, nrf_gpiote_polarity_t action)
{
    //Do nothing
}
// ### Workaround Section End   ###

in spi_event_handler, add this at right after NRF_DRV_SPI_EVENT_DONE

 // ### Workaround Section Start ###

// Disable the PPI channel
err_code = nrf_drv_ppi_channel_disable(ppi_channel);
APP_ERROR_CHECK(err_code);

// Disable a GPIOTE output pin task.
nrf_drv_gpiote_in_event_disable(SPI_SCK_PIN);

// ### Workaround Section End   ###

after APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL)); in main(), you add this:

// ### Workaround Section Start ###
    
     uint32_t err_code;
    
     NRF_SPIM_Type * p_spim = spi.p_registers;
    
    //Initialize GPIOTE and PPI drivers for the workaround
    
    err_code = nrf_drv_gpiote_init();
    APP_ERROR_CHECK(err_code);
    
    // Initializes the GPIOTE channel so that SCK toggles generates events
    nrf_drv_gpiote_in_config_t config = GPIOTE_CONFIG_IN_SENSE_TOGGLE(true);
            err_code = nrf_drv_gpiote_in_init(SPI_SCK_PIN, &config, in_pin_handler);
            APP_ERROR_CHECK(err_code); 
        
    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);
    
    // Allocate first unused PPI channel 
    err_code = nrf_drv_ppi_channel_alloc(&ppi_channel);
    APP_ERROR_CHECK(err_code);
    
    // Assign the PPI channel to the SCK pin
    err_code = nrf_drv_ppi_channel_assign(ppi_channel,
                                        nrf_drv_gpiote_in_event_addr_get(SPI_SCK_PIN),
                                        (uint32_t)&p_spim->TASKS_STOP);
    APP_ERROR_CHECK(err_code);


// ### Workaround Section End   ###    

Then use the function spi_send_recv when you want to send 1 byte data