a Nrf52 function mapping to nrf51

Question

Hi all, 
 I am working on interfacing an SD card as well as an OLED Display with my nrf51422 on SDK 12.2.0. 
 Although, both are on SPI and hence i need to configure them as multiple slaves using multiple master instances instead. I got a way on how to do it which is given here.[link text]:- 
 ( devzone.nordicsemi.com/.../ 
 Although this is done over nrf52, and i m getting a problem in the line:- 
 "volatile spi_control_block_t * my_setup = mw_spi_instance.drv_inst_idx;" 
 which says "mw_spi_instance" is undeclared. 
 Thus i want to know on how i should proceed further. Is there a parallel function in nrf51422 which can be supported replacing it? 
 Thank you in advance.

Jørgen Holmefjord · Accepted Answer

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Jørgen Holmefjord · Answer

Hi, 
 I looked into this futher, and don't understand exactly how the solution is meant to work. I propose the following alternative, which require less changes to the files: 
 Declare the function nrf_drv_spi_switch_chips() in nrf_drv_spi.h , right below nrf_drv_spi_uninit() : 
 void nrf_drv_spi_switch_chips( nrf_drv_spi_t const * const p_instance,
 uint32_t chip_select );
 
 Implement the function in nrf_drv_spi.c (below nrf_drv_spi_uninit() ): 
 void nrf_drv_spi_switch_chips( nrf_drv_spi_t const * const p_instance,
 uint32_t chip_select )
{
 spi_control_block_t * p_cb = &m_cb[p_instance->drv_inst_idx];
 p_cb->ss_pin = chip_select;

 //A Slave select must be set as high before setting it as output,
 //because during connect it to the pin it causes glitches.
 nrf_gpio_pin_set(p_cb->ss_pin);
 nrf_gpio_cfg_output(p_cb->ss_pin);
 nrf_gpio_pin_set(p_cb->ss_pin);
}
 
 You can now call the function with the SPI instance and SS pin as argument from any files including nrf_drv_spi.h (modified SPI master example from SDK 12.3.0): 
 static const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE); /**< SPI instance. */
#define SPI_SS_PIN_1 29
#define SPI_SS_PIN_2 30

...

int main(void)
{
 NRF_LOG_INFO("SPI example
");

 nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
 spi_config.ss_pin = SPI_SS_PIN;
 spi_config.miso_pin = SPI_MISO_PIN;
 spi_config.mosi_pin = SPI_MOSI_PIN;
 spi_config.sck_pin = SPI_SCK_PIN;
 APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler));

 while (1)
 {
 // Reset rx buffer and transfer done flag
 memset(m_rx_buf, 0, m_length);
 spi_xfer_done = false;

 APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));

 while (!spi_xfer_done)
 {
 __WFE();
 }
 nrf_drv_spi_switch_chips(&spi, SPI_SS_PIN_2);

 APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));

 while (!spi_xfer_done)
 {
 __WFE();
 }
 nrf_drv_spi_switch_chips(&spi, SPI_SS_PIN_1);
 }
}
 
 Best regards, 
 Jørgen

Jørgen Holmefjord · Answer

This was not meant as a full example. You need to merge it into the SPI example from the SDK. m_rx_buffer, rx_length, spi_xfer_done, m_tx_buf, m_length, m_rx_buf, amd m_length is defined there.

a Nrf52 function mapping to nrf51

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