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sam3x8e: Read from the SPI_RDR on SPI send even if no data needed 

Be sure to read the SPI_RDR as that clears the RDRF flag.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2018-07-05 10:29:52 -04:00
parent 7e9ee6aef7
commit 1eb416002b
1 changed files with 9 additions and 8 deletions
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17
src/sam3x8e/spi.c
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@ -4,13 +4,10 @@
// //
// This file may be distributed under the terms of the GNU GPLv3 license. // This file may be distributed under the terms of the GNU GPLv3 license.
#include <stddef.h> // NULL #include <sam3x8e.h> // REGPTR
#include "autoconf.h"
#include "command.h" // shutdown #include "command.h" // shutdown
#include "gpio.h" #include "gpio.h" // gpio_peripheral
#include "sched.h" #include "sched.h" // sched_shutdown
#include <sam3x8e.h>
#include <string.h>
#define REGPTR SPI0 #define REGPTR SPI0
#define PERIPH_ID ID_SPI0 #define PERIPH_ID ID_SPI0
@ -109,7 +106,8 @@ spi_transfer(struct spi_config config, uint8_t receive_data
while (len--) { while (len--) {
pSpi->SPI_TDR = *data; pSpi->SPI_TDR = *data;
// wait for receive register // wait for receive register
while (!(pSpi->SPI_SR & SPI_SR_RDRF)) { asm volatile("nop"); }; while (!(pSpi->SPI_SR & SPI_SR_RDRF))
;
// get data // get data
*data++ = pSpi->SPI_RDR; *data++ = pSpi->SPI_RDR;
} }
@ -117,7 +115,10 @@ spi_transfer(struct spi_config config, uint8_t receive_data
while (len--) { while (len--) {
pSpi->SPI_TDR = *data++; pSpi->SPI_TDR = *data++;
// wait for receive register // wait for receive register
while (!(pSpi->SPI_SR & SPI_SR_RDRF)) { asm volatile("nop"); }; while (!(pSpi->SPI_SR & SPI_SR_RDRF))
;
// read data (to clear RDRF)
pSpi->SPI_RDR;
} }
} }
} }