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Incorporated review feedback for simplfied _go_idle_state() implementation with 1ms wait between response queries.

pull/7774/head
Simon Hughes 2017-04-06 12:47:47 +01:00
parent 88fecd54d6
commit 5830844aa3
2 changed files with 26 additions and 26 deletions
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40
features/filesystem/sd/SDBlockDevice.cpp
View File

@ -147,10 +147,11 @@
#include "SDBlockDevice.h"
#include "mbed_debug.h"
#define SD_COMMAND_TIMEOUT 5000
#define SD_CMD0_GO_IDLE_STATE_RETRIES 3
#define SD_CMD0_GO_IDLE_STATE 0x00
#define SD_DBG 0
#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_DBG 0
#define SD_BLOCK_DEVICE_ERROR_WOULD_BLOCK -5001 /*!< operation would block */
#define SD_BLOCK_DEVICE_ERROR_UNSUPPORTED -5002 /*!< unsupported operation */
@ -509,30 +510,18 @@ int SDBlockDevice::_cmd8() {
return -1; // timeout
}
/* SDBlockDevice::_go_idle_state()
*
* ARGUMENTS
* None
* DETAILS:
* Put the SDCard into the SPI Mode idle state by sending the CMD0
* (GO_IDLE_STATE) command. See the notes in the "SPI Startup" section
* of the comments at the head of this file.
*
* RETURN:
* -1 an error occured e.g. a valid response was not received.
* R1_IDLE_STATE (0x1), the successful response from CMD0.
*/
int SDBlockDevice::_go_idle_state() {
_spi.lock();
_cs = 0;
int cmd_arg = 0; /* CMD0 argument is just "stuff bits"*/
int cmd_arg = 0; /* CMD0 argument is just "stuff bits" */
int ret = SD_CMD0_INVALID_RESPONSE_TIMEOUT;
/* 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 interpretted as a command and get lost. For some cards retrying
* not be interpreted as a command and get lost. For some cards retrying
* the command overcomes this situation. */
for (int num_retries = 0; num_retries < SD_CMD0_GO_IDLE_STATE_RETRIES; num_retries++) {
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);
@ -541,23 +530,22 @@ int SDBlockDevice::_go_idle_state() {
_spi.write(cmd_arg >> 0);
_spi.write(0x95);
// wait for the response (response[7] == 0)
/* 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)) {
_cs = 1;
_spi.write(0xFF);
_spi.unlock();
return response;
ret = response;
break;
}
wait_ms(1);
}
}
_cs = 1;
_spi.write(0xFF);
_spi.unlock();
return -1; // timeout
return ret;
}
int SDBlockDevice::_read(uint8_t *buffer, uint32_t length) {

12
features/filesystem/sd/SDBlockDevice.h
View File

@ -132,6 +132,18 @@ private:
int _cmdx(int cmd, int arg);
int _cmd8();
int _cmd58();
/* Move the SDCard into the SPI Mode idle state
*
* The card is transitioned from SDCard mode to SPI mode by sending the
* CMD0 (GO_IDLE_STATE) command with CS asserted. See the notes in the
* "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.
*/
int _go_idle_state();
int _initialise_card();
int _initialise_card_v1();