mirror of https://github.com/ARMmbed/mbed-os.git
Incorporated review feedback for simplfied _go_idle_state() implementation with 1ms wait between response queries.
parent
88fecd54d6
commit
5830844aa3
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@ -147,10 +147,11 @@
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#include "SDBlockDevice.h"
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#include "mbed_debug.h"
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#define SD_COMMAND_TIMEOUT 5000
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#define SD_CMD0_GO_IDLE_STATE_RETRIES 3
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#define SD_CMD0_GO_IDLE_STATE 0x00
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#define SD_DBG 0
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#define SD_COMMAND_TIMEOUT 5000 /*!< Number of times to query card for correct result */
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#define SD_CMD0_GO_IDLE_STATE_RETRIES 3 /*!< Number of retries for sending CMDO*/
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#define SD_CMD0_GO_IDLE_STATE 0x00 /*!< CMD0 code value */
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#define SD_CMD0_INVALID_RESPONSE_TIMEOUT -1 /*!< CMD0 received invalid responses and timed out */
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#define SD_DBG 0
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#define SD_BLOCK_DEVICE_ERROR_WOULD_BLOCK -5001 /*!< operation would block */
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#define SD_BLOCK_DEVICE_ERROR_UNSUPPORTED -5002 /*!< unsupported operation */
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@ -509,30 +510,18 @@ int SDBlockDevice::_cmd8() {
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return -1; // timeout
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}
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/* SDBlockDevice::_go_idle_state()
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*
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* ARGUMENTS
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* None
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* DETAILS:
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* Put the SDCard into the SPI Mode idle state by sending the CMD0
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* (GO_IDLE_STATE) command. See the notes in the "SPI Startup" section
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* of the comments at the head of this file.
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*
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* RETURN:
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* -1 an error occured e.g. a valid response was not received.
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* R1_IDLE_STATE (0x1), the successful response from CMD0.
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*/
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int SDBlockDevice::_go_idle_state() {
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_spi.lock();
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_cs = 0;
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int cmd_arg = 0; /* CMD0 argument is just "stuff bits"*/
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int cmd_arg = 0; /* CMD0 argument is just "stuff bits" */
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int ret = SD_CMD0_INVALID_RESPONSE_TIMEOUT;
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/* Reseting the MCU SPI master may not reset the on-board SDCard, in which
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* case when MCU power-on occurs the SDCard will resume operations as
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* though there was no reset. In this scenario the first CMD0 will
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* not be interpretted as a command and get lost. For some cards retrying
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* not be interpreted as a command and get lost. For some cards retrying
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* the command overcomes this situation. */
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for (int num_retries = 0; num_retries < SD_CMD0_GO_IDLE_STATE_RETRIES; num_retries++) {
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for (int num_retries = 0; ret != R1_IDLE_STATE && (num_retries < SD_CMD0_GO_IDLE_STATE_RETRIES); num_retries++) {
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/* send a CMD0 */
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_spi.write(0x40 | SD_CMD0_GO_IDLE_STATE);
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_spi.write(cmd_arg >> 24);
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@ -541,23 +530,22 @@ int SDBlockDevice::_go_idle_state() {
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_spi.write(cmd_arg >> 0);
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_spi.write(0x95);
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// wait for the response (response[7] == 0)
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/* wait for the R1_IDLE_STATE response */
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for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
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int response = _spi.write(0xFF);
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/* Explicitly check for the R1_IDLE_STATE response rather that most significant bit
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* being 0 because invalid data can be returned. */
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if ((response == R1_IDLE_STATE)) {
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_cs = 1;
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_spi.write(0xFF);
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_spi.unlock();
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return response;
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ret = response;
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break;
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}
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wait_ms(1);
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}
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}
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_cs = 1;
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_spi.write(0xFF);
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_spi.unlock();
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return -1; // timeout
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return ret;
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}
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int SDBlockDevice::_read(uint8_t *buffer, uint32_t length) {
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@ -132,6 +132,18 @@ private:
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int _cmdx(int cmd, int arg);
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int _cmd8();
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int _cmd58();
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/* Move the SDCard into the SPI Mode idle state
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*
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* The card is transitioned from SDCard mode to SPI mode by sending the
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* CMD0 (GO_IDLE_STATE) command with CS asserted. See the notes in the
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* "SPI Startup" section of the comments at the head of the
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* implementation file for further details and specification references.
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*
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* @return -1 if an error occurred e.g. a valid response was not
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* received. Otherwise R1_IDLE_STATE (0x1), the successful
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* response from CMD0.
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*/
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int _go_idle_state();
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int _initialise_card();
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int _initialise_card_v1();
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