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Using _cmd for _go_idle_state funciton

pull/7774/head
Deepika 2017-06-21 12:08:49 -05:00
parent e68d54efd0
commit 547da1b24c
2 changed files with 16 additions and 36 deletions
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45
features/filesystem/sd/SDBlockDevice.cpp
View File

@ -148,9 +148,7 @@
#include "mbed_debug.h"
#define SD_COMMAND_TIMEOUT 5000 /*!< Number of times to query card for correct result */
#define SD_CMD0_GO_IDLE_STATE_RETRIES 3 /*!< Number of retries for sending CMDO*/
#define SD_CMD0_GO_IDLE_STATE 0x00 /*!< CMD0 code value */
#define SD_CMD0_INVALID_RESPONSE_TIMEOUT -1 /*!< CMD0 received invalid responses and timed out */
#define SD_CMD0_GO_IDLE_STATE_RETRIES 5 /*!< Number of retries for sending CMDO */
#define SD_DBG 1
#define SD_BLOCK_DEVICE_ERROR_WOULD_BLOCK -5001 /*!< operation would block */
@ -251,9 +249,12 @@ SDBlockDevice::~SDBlockDevice()
int SDBlockDevice::_initialise_card()
{
_dbg = SD_DBG;
// Initialize the SPI interface: Card by default is in SD mode
_spi_init();
/* Transition from SD Card mode to SPI mode by sending CMD0 GO_IDLE_STATE command */
// The card is transitioned from SDCard mode to SPI mode by sending the
// CMD0 (GO_IDLE_STATE) command with CS asserted
if (_go_idle_state() != R1_IDLE_STATE) {
debug_if(_dbg, "No disk, or could not put SD card in to SPI idle state\n");
return SD_BLOCK_DEVICE_ERROR_NO_DEVICE;
@ -572,40 +573,21 @@ int SDBlockDevice::_cmd8() {
_deselect();
return -1; // timeout
}
uint32_t SDBlockDevice::_go_idle_state() {
uint32_t response;
int SDBlockDevice::_go_idle_state() {
int cmd_arg = 0; /* CMD0 argument is just "stuff bits" */
int ret = SD_CMD0_INVALID_RESPONSE_TIMEOUT;
_select();
/* Reseting the MCU SPI master may not reset the on-board SDCard, in which
* case when MCU power-on occurs the SDCard will resume operations as
* though there was no reset. In this scenario the first CMD0 will
* not be interpreted as a command and get lost. For some cards retrying
* the command overcomes this situation. */
for (int num_retries = 0; ret != R1_IDLE_STATE && (num_retries < SD_CMD0_GO_IDLE_STATE_RETRIES); num_retries++) {
/* send a CMD0 */
_spi.write(0x40 | SD_CMD0_GO_IDLE_STATE);
_spi.write(cmd_arg >> 24);
_spi.write(cmd_arg >> 16);
_spi.write(cmd_arg >> 8);
_spi.write(cmd_arg >> 0);
_spi.write(0x95);
/* wait for the R1_IDLE_STATE response */
for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
int response = _spi.write(0xFF);
/* Explicitly check for the R1_IDLE_STATE response rather that most significant bit
* being 0 because invalid data can be returned. */
if ((response == R1_IDLE_STATE)) {
ret = response;
break;
}
wait_ms(1);
}
for (int i = 0; i < SD_CMD0_GO_IDLE_STATE_RETRIES; i++) {
_cmd(CMD0_GO_IDLE_STATE, 0, &response);
if (R1_IDLE_STATE == response)
break;
wait_ms(1);
}
_deselect();
return ret;
return response;
}
int SDBlockDevice::_read(uint8_t *buffer, uint32_t length) {
@ -733,7 +715,6 @@ void SDBlockDevice::_spi_init() {
_spi.unlock();
}
void SDBlockDevice::_select() {
_spi.lock();
_cs = 0;

7
features/filesystem/sd/SDBlockDevice.h
View File

@ -179,11 +179,10 @@ private:
* "SPI Startup" section of the comments at the head of the
* implementation file for further details and specification references.
*
* @return -1 if an error occurred e.g. a valid response was not
* received. Otherwise R1_IDLE_STATE (0x1), the successful
* response from CMD0.
* @return Response form the card. R1_IDLE_STATE (0x1), the successful
* response from CMD0. R1_XXX_XXX for more response
*/
int _go_idle_state();
uint32_t _go_idle_state();
int _initialise_card();
int _initialise_card_v1();
int _initialise_card_v2();