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Simon Ford / Mbed 2 deprecated SDCardTest

SDFileSystem.cpp@2:849162a1207f, 2009-12-14 (annotated)

Committer:: simon
Date:: Mon Dec 14 22:32:28 2009 +0000
Revision:: 2:849162a1207f
Parent:: 1:2dec995d53f8
Child:: 3:68ef62208d4d

Who changed what in which revision?

User	Revision	Line number	New contents of line
simon	1:2dec995d53f8	1	/* mbed Microcontroller Library - SDFileSystem
simon	1:2dec995d53f8	2	* Copyright (c) 2008-2009, sford
simon	1:2dec995d53f8	3	*
simon	1:2dec995d53f8	4	* Introduction
simon	1:2dec995d53f8	5	* ------------
simon	1:2dec995d53f8	6	* SD and MMC cards support a number of interfaces, but common to them all
simon	1:2dec995d53f8	7	* is one based on SPI. This is the one I'm implmenting because it means
simon	1:2dec995d53f8	8	* it is much more portable even though not so performant, and we already
simon	1:2dec995d53f8	9	* have the mbed SPI Interface!
simon	1:2dec995d53f8	10	*
simon	1:2dec995d53f8	11	* The main reference I'm using is Chapter 7, "SPI Mode" of:
simon	1:2dec995d53f8	12	* http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
simon	1:2dec995d53f8	13	*
simon	1:2dec995d53f8	14	* SPI Startup
simon	1:2dec995d53f8	15	* -----------
simon	1:2dec995d53f8	16	* The SD card powers up in SD mode. The SPI interface mode is selected by
simon	1:2dec995d53f8	17	* asserting CS low and sending the reset command (CMD0). The card will
simon	1:2dec995d53f8	18	* respond with a (R1) response.
simon	1:2dec995d53f8	19	*
simon	1:2dec995d53f8	20	* CMD8 is optionally sent to determine the voltage range supported, and
simon	1:2dec995d53f8	21	* indirectly determine whether it is a version 1.x SD/non-SD card or
simon	1:2dec995d53f8	22	* version 2.x. I'll just ignore this for now.
simon	1:2dec995d53f8	23	*
simon	1:2dec995d53f8	24	* ACMD41 is repeatedly issued to initialise the card, until "in idle"
simon	1:2dec995d53f8	25	* (bit 0) of the R1 response goes to '0', indicating it is initialised.
simon	1:2dec995d53f8	26	*
simon	1:2dec995d53f8	27	* You should also indicate whether the host supports High Capicity cards,
simon	1:2dec995d53f8	28	* and check whether the card is high capacity - i'll also ignore this
simon	1:2dec995d53f8	29	*
simon	1:2dec995d53f8	30	* SPI Protocol
simon	1:2dec995d53f8	31	* ------------
simon	1:2dec995d53f8	32	* The SD SPI protocol is based on transactions made up of 8-bit words, with
simon	1:2dec995d53f8	33	* the host starting every bus transaction by asserting the CS signal low. The
simon	1:2dec995d53f8	34	* card always responds to commands, data blocks and errors.
simon	1:2dec995d53f8	35	*
simon	1:2dec995d53f8	36	* The protocol supports a CRC, but by default it is off (except for the
simon	1:2dec995d53f8	37	* first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
simon	1:2dec995d53f8	38	* I'll leave the CRC off I think!
simon	1:2dec995d53f8	39	*
simon	1:2dec995d53f8	40	* Standard capacity cards have variable data block sizes, whereas High
simon	1:2dec995d53f8	41	* Capacity cards fix the size of data block to 512 bytes. I'll therefore
simon	1:2dec995d53f8	42	* just always use the Standard Capacity cards with a block size of 512 bytes.
simon	1:2dec995d53f8	43	* This is set with CMD16.
simon	1:2dec995d53f8	44	*
simon	1:2dec995d53f8	45	* You can read and write single blocks (CMD17, CMD25) or multiple blocks
simon	1:2dec995d53f8	46	* (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
simon	1:2dec995d53f8	47	* the card gets a read command, it responds with a response token, and then
simon	1:2dec995d53f8	48	* a data token or an error.
simon	1:2dec995d53f8	49	*
simon	1:2dec995d53f8	50	* SPI Command Format
simon	1:2dec995d53f8	51	* ------------------
simon	1:2dec995d53f8	52	* Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
simon	1:2dec995d53f8	53	*
simon	1:2dec995d53f8	54	* +---------------+------------+------------+-----------+----------+--------------+
simon	1:2dec995d53f8	55	* \| 01 \| cmd[5:0] \| arg[31:24] \| arg[23:16] \| arg[15:8] \| arg[7:0] \| crc[6:0] \| 1 \|
simon	1:2dec995d53f8	56	* +---------------+------------+------------+-----------+----------+--------------+
simon	1:2dec995d53f8	57	*
simon	1:2dec995d53f8	58	* As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
simon	1:2dec995d53f8	59	*
simon	1:2dec995d53f8	60	* All Application Specific commands shall be preceded with APP_CMD (CMD55).
simon	1:2dec995d53f8	61	*
simon	1:2dec995d53f8	62	* SPI Response Format
simon	1:2dec995d53f8	63	* -------------------
simon	1:2dec995d53f8	64	* The main response format (R1) is a status byte (normally zero). Key flags:
simon	1:2dec995d53f8	65	* idle - 1 if the card is in an idle state/initialising
simon	1:2dec995d53f8	66	* cmd - 1 if an illegal command code was detected
simon	1:2dec995d53f8	67	*
simon	1:2dec995d53f8	68	* +-------------------------------------------------+
simon	1:2dec995d53f8	69	* R1 \| 0 \| arg \| addr \| seq \| crc \| cmd \| erase \| idle \|
simon	1:2dec995d53f8	70	* +-------------------------------------------------+
simon	1:2dec995d53f8	71	*
simon	1:2dec995d53f8	72	* R1b is the same, except it is followed by a busy signal (zeros) until
simon	1:2dec995d53f8	73	* the first non-zero byte when it is ready again.
simon	1:2dec995d53f8	74	*
simon	1:2dec995d53f8	75	* Data Response Token
simon	1:2dec995d53f8	76	* -------------------
simon	1:2dec995d53f8	77	* Every data block written to the card is acknowledged by a byte
simon	1:2dec995d53f8	78	* response token
simon	1:2dec995d53f8	79	*
simon	1:2dec995d53f8	80	* +----------------------+
simon	1:2dec995d53f8	81	* \| xxx \| 0 \| status \| 1 \|
simon	1:2dec995d53f8	82	* +----------------------+
simon	1:2dec995d53f8	83	* 010 - OK!
simon	1:2dec995d53f8	84	* 101 - CRC Error
simon	1:2dec995d53f8	85	* 110 - Write Error
simon	1:2dec995d53f8	86	*
simon	1:2dec995d53f8	87	* Single Block Read and Write
simon	1:2dec995d53f8	88	* ---------------------------
simon	1:2dec995d53f8	89	*
simon	1:2dec995d53f8	90	* Block transfers have a byte header, followed by the data, followed
simon	1:2dec995d53f8	91	* by a 16-bit CRC. In our case, the data will always be 512 bytes.
simon	1:2dec995d53f8	92	*
simon	1:2dec995d53f8	93	* +------+---------+---------+- - - -+---------+-----------+----------+
simon	1:2dec995d53f8	94	* \| 0xFE \| data[0] \| data[1] \| \| data[n] \| crc[15:8] \| crc[7:0] \|
simon	1:2dec995d53f8	95	* +------+---------+---------+- - - -+---------+-----------+----------+
simon	1:2dec995d53f8	96	*/
simon	1:2dec995d53f8	97
simon	1:2dec995d53f8	98	#include "SDFileSystem.h"
simon	1:2dec995d53f8	99
simon	1:2dec995d53f8	100	#define SD_COMMAND_TIMEOUT 5000
simon	1:2dec995d53f8	101
simon	1:2dec995d53f8	102	SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
simon	1:2dec995d53f8	103	FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
simon	1:2dec995d53f8	104	_cs = 1;
simon	1:2dec995d53f8	105	}
simon	1:2dec995d53f8	106
simon	2:849162a1207f	107	#define R1_IDLE_STATE (1 << 0)
simon	2:849162a1207f	108	#define R1_ERASE_RESET (1 << 1)
simon	2:849162a1207f	109	#define R1_ILLEGAL_COMMAND (1 << 2)
simon	2:849162a1207f	110	#define R1_COM_CRC_ERROR (1 << 3)
simon	2:849162a1207f	111	#define R1_ERASE_SEQUENCE_ERROR (1 << 4)
simon	2:849162a1207f	112	#define R1_ADDRESS_ERROR (1 << 5)
simon	2:849162a1207f	113	#define R1_PARAMETER_ERROR (1 << 6)
simon	2:849162a1207f	114
simon	1:2dec995d53f8	115	int SDFileSystem::disk_initialize() {
simon	1:2dec995d53f8	116
simon	1:2dec995d53f8	117	_spi.frequency(100000); // Set to 100kHz for initialisation
simon	1:2dec995d53f8	118
simon	1:2dec995d53f8	119	// Initialise the card by clocking it with cs = 1
simon	1:2dec995d53f8	120	_cs = 1;
simon	1:2dec995d53f8	121	for(int i=0; i<16; i++) {
simon	1:2dec995d53f8	122	_spi.write(0xFF);
simon	1:2dec995d53f8	123	}
simon	1:2dec995d53f8	124
simon	1:2dec995d53f8	125	// send CMD0, should return with all zeros except IDLE STATE set (bit 0)
simon	2:849162a1207f	126	if(_cmd(0, 0) != R1_IDLE_STATE) {
simon	2:849162a1207f	127	fprintf(stderr, "No disk, or could not put SD card in to SPI idle state\n");
simon	1:2dec995d53f8	128	return 1;
simon	1:2dec995d53f8	129	}
simon	2:849162a1207f	130
simon	2:849162a1207f	131	int r = _cmd8();
simon	2:849162a1207f	132	if(r == R1_IDLE_STATE) {
simon	2:849162a1207f	133	printf("SD version 2.x\n");
simon	2:849162a1207f	134	} else if(r == (R1_IDLE_STATE \| R1_ILLEGAL_COMMAND)) {
simon	2:849162a1207f	135	printf("SD version 1.x\n");
simon	2:849162a1207f	136	} else {
simon	2:849162a1207f	137	error("Unknown SD version\n");
simon	2:849162a1207f	138	}
simon	2:849162a1207f	139
simon	1:2dec995d53f8	140	// ACMD41 to give host capacity support (repeat until not busy)
simon	1:2dec995d53f8	141	// ACMD41 is application specific command, so we send APP_CMD (CMD55) beforehand
simon	1:2dec995d53f8	142	for(int i=0;; i++) {
simon	1:2dec995d53f8	143	_cmd(55, 0);
simon	1:2dec995d53f8	144	int response = _cmd(41, 0);
simon	1:2dec995d53f8	145	if(response == 0) {
simon	1:2dec995d53f8	146	break;
simon	1:2dec995d53f8	147	} else if(i > SD_COMMAND_TIMEOUT) {
simon	1:2dec995d53f8	148	fprintf(stderr, "Timeout waiting for card\n");
simon	1:2dec995d53f8	149	return 1;
simon	1:2dec995d53f8	150	}
simon	1:2dec995d53f8	151	}
simon	1:2dec995d53f8	152
simon	2:849162a1207f	153	printf("OK\n");
simon	2:849162a1207f	154
simon	1:2dec995d53f8	155	_sectors = _sd_sectors();
simon	1:2dec995d53f8	156
simon	1:2dec995d53f8	157	// Set block length to 512 (CMD16)
simon	1:2dec995d53f8	158	if(_cmd(16, 512) != 0) {
simon	1:2dec995d53f8	159	fprintf(stderr, "Set block timeout\n");
simon	1:2dec995d53f8	160	return 1;
simon	1:2dec995d53f8	161	}
simon	1:2dec995d53f8	162
simon	1:2dec995d53f8	163	_spi.frequency(1000000); // Set to 1MHz for data transfer
simon	1:2dec995d53f8	164	return 0;
simon	1:2dec995d53f8	165	}
simon	1:2dec995d53f8	166
simon	1:2dec995d53f8	167	int SDFileSystem::disk_write(const char *buffer, int block_number) {
simon	1:2dec995d53f8	168	// set write address for single block (CMD24)
simon	1:2dec995d53f8	169	if(_cmd(24, block_number * 512) != 0) {
simon	1:2dec995d53f8	170	return 1;
simon	1:2dec995d53f8	171	}
simon	1:2dec995d53f8	172
simon	1:2dec995d53f8	173	// send the data block
simon	1:2dec995d53f8	174	_write(buffer, 512);
simon	1:2dec995d53f8	175	return 0;
simon	1:2dec995d53f8	176	}
simon	1:2dec995d53f8	177
simon	1:2dec995d53f8	178	int SDFileSystem::disk_read(char *buffer, int block_number) {
simon	1:2dec995d53f8	179	// set read address for single block (CMD17)
simon	1:2dec995d53f8	180	if(_cmd(17, block_number * 512) != 0) {
simon	1:2dec995d53f8	181	return 1;
simon	1:2dec995d53f8	182	}
simon	1:2dec995d53f8	183
simon	1:2dec995d53f8	184	// receive the data
simon	1:2dec995d53f8	185	_read(buffer, 512);
simon	1:2dec995d53f8	186	return 0;
simon	1:2dec995d53f8	187	}
simon	1:2dec995d53f8	188
simon	1:2dec995d53f8	189	int SDFileSystem::disk_status() { return 0; }
simon	1:2dec995d53f8	190	int SDFileSystem::disk_sync() { return 0; }
simon	1:2dec995d53f8	191	int SDFileSystem::disk_sectors() { return _sectors; }
simon	1:2dec995d53f8	192
simon	1:2dec995d53f8	193	// PRIVATE FUNCTIONS
simon	1:2dec995d53f8	194
simon	1:2dec995d53f8	195	int SDFileSystem::_cmd(int cmd, int arg) {
simon	1:2dec995d53f8	196	_cs = 0;
simon	1:2dec995d53f8	197
simon	1:2dec995d53f8	198	// send a command
simon	1:2dec995d53f8	199	_spi.write(0x40 \| cmd);
simon	1:2dec995d53f8	200	_spi.write(arg >> 24);
simon	1:2dec995d53f8	201	_spi.write(arg >> 16);
simon	1:2dec995d53f8	202	_spi.write(arg >> 8);
simon	1:2dec995d53f8	203	_spi.write(arg >> 0);
simon	1:2dec995d53f8	204	_spi.write(0x95);
simon	1:2dec995d53f8	205
simon	1:2dec995d53f8	206	// wait for the repsonse (response[7] == 0)
simon	1:2dec995d53f8	207	for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
simon	1:2dec995d53f8	208	int response = _spi.write(0xFF);
simon	1:2dec995d53f8	209	if(!(response & 0x80)) {
simon	1:2dec995d53f8	210	_cs = 1;
simon	1:2dec995d53f8	211	_spi.write(0xFF);
simon	1:2dec995d53f8	212	return response;
simon	1:2dec995d53f8	213	}
simon	1:2dec995d53f8	214	}
simon	1:2dec995d53f8	215	_cs = 1;
simon	1:2dec995d53f8	216	_spi.write(0xFF);
simon	1:2dec995d53f8	217	return -1; // timeout
simon	1:2dec995d53f8	218	}
simon	1:2dec995d53f8	219
simon	2:849162a1207f	220	int SDFileSystem::_cmd8() {
simon	2:849162a1207f	221	_cs = 0;
simon	2:849162a1207f	222
simon	2:849162a1207f	223	// send a command
simon	2:849162a1207f	224	_spi.write(0x40 \| 8); // CMD8
simon	2:849162a1207f	225	_spi.write(0x00); // reserved
simon	2:849162a1207f	226	_spi.write(0x00); // reserved
simon	2:849162a1207f	227	_spi.write(0x01); // 3.3v
simon	2:849162a1207f	228	_spi.write(0xAA); // check pattern
simon	2:849162a1207f	229	_spi.write(0x87); // crc
simon	2:849162a1207f	230
simon	2:849162a1207f	231	// wait for the repsonse (response[7] == 0)
simon	2:849162a1207f	232	for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) {
simon	2:849162a1207f	233	char response[5];
simon	2:849162a1207f	234	response[0] = _spi.write(0xFF);
simon	2:849162a1207f	235	if(!(response[0] & 0x80)) {
simon	2:849162a1207f	236	for(int j=1; j<5; j++) {
simon	2:849162a1207f	237	response[i] = _spi.write(0xFF);
simon	2:849162a1207f	238	}
simon	2:849162a1207f	239	_cs = 1;
simon	2:849162a1207f	240	_spi.write(0xFF);
simon	2:849162a1207f	241	return response[0];
simon	2:849162a1207f	242	}
simon	2:849162a1207f	243	}
simon	2:849162a1207f	244	_cs = 1;
simon	2:849162a1207f	245	_spi.write(0xFF);
simon	2:849162a1207f	246	return -1; // timeout
simon	2:849162a1207f	247	}
simon	2:849162a1207f	248
simon	1:2dec995d53f8	249	int SDFileSystem::_read(char *buffer, int length) {
simon	1:2dec995d53f8	250	_cs = 0;
simon	1:2dec995d53f8	251
simon	1:2dec995d53f8	252	// read until start byte (0xFF)
simon	1:2dec995d53f8	253	while(_spi.write(0xFF) != 0xFE);
simon	1:2dec995d53f8	254
simon	1:2dec995d53f8	255	// read data
simon	1:2dec995d53f8	256	for(int i=0; i<length; i++) {
simon	1:2dec995d53f8	257	buffer[i] = _spi.write(0xFF);
simon	1:2dec995d53f8	258	}
simon	1:2dec995d53f8	259	_spi.write(0xFF); // checksum
simon	1:2dec995d53f8	260	_spi.write(0xFF);
simon	1:2dec995d53f8	261
simon	1:2dec995d53f8	262	_cs = 1;
simon	1:2dec995d53f8	263	_spi.write(0xFF);
simon	1:2dec995d53f8	264	return 0;
simon	1:2dec995d53f8	265	}
simon	1:2dec995d53f8	266
simon	1:2dec995d53f8	267	int SDFileSystem::_write(const char *buffer, int length) {
simon	1:2dec995d53f8	268	_cs = 0;
simon	1:2dec995d53f8	269
simon	1:2dec995d53f8	270	// indicate start of block
simon	1:2dec995d53f8	271	_spi.write(0xFE);
simon	1:2dec995d53f8	272
simon	1:2dec995d53f8	273	// write the data
simon	1:2dec995d53f8	274	for(int i=0; i<length; i++) {
simon	1:2dec995d53f8	275	_spi.write(buffer[i]);
simon	1:2dec995d53f8	276	}
simon	1:2dec995d53f8	277
simon	1:2dec995d53f8	278	// write the checksum
simon	1:2dec995d53f8	279	_spi.write(0xFF);
simon	1:2dec995d53f8	280	_spi.write(0xFF);
simon	1:2dec995d53f8	281
simon	1:2dec995d53f8	282	// check the repsonse token
simon	1:2dec995d53f8	283	if((_spi.write(0xFF) & 0x1F) != 0x05) {
simon	1:2dec995d53f8	284	_cs = 1;
simon	1:2dec995d53f8	285	_spi.write(0xFF);
simon	1:2dec995d53f8	286	return 1;
simon	1:2dec995d53f8	287	}
simon	1:2dec995d53f8	288
simon	1:2dec995d53f8	289	// wait for write to finish
simon	1:2dec995d53f8	290	while(_spi.write(0xFF) == 0);
simon	1:2dec995d53f8	291
simon	1:2dec995d53f8	292	_cs = 1;
simon	1:2dec995d53f8	293	_spi.write(0xFF);
simon	1:2dec995d53f8	294	return 0;
simon	1:2dec995d53f8	295	}
simon	1:2dec995d53f8	296
simon	1:2dec995d53f8	297	static int ext_bits(char *data, int msb, int lsb) {
simon	1:2dec995d53f8	298	int bits = 0;
simon	1:2dec995d53f8	299	int size = 1 + msb - lsb;
simon	1:2dec995d53f8	300	for(int i=0; i<size; i++) {
simon	1:2dec995d53f8	301	int position = lsb + i;
simon	1:2dec995d53f8	302	int byte = 15 - (position >> 3);
simon	1:2dec995d53f8	303	int bit = position & 0x7;
simon	1:2dec995d53f8	304	int value = (data[byte] >> bit) & 1;
simon	1:2dec995d53f8	305	bits \|= value << i;
simon	1:2dec995d53f8	306	}
simon	1:2dec995d53f8	307	return bits;
simon	1:2dec995d53f8	308	}
simon	1:2dec995d53f8	309
simon	1:2dec995d53f8	310	int SDFileSystem::_sd_sectors() {
simon	1:2dec995d53f8	311
simon	1:2dec995d53f8	312	// CMD9, Response R2 (R1 byte + 16-byte block read)
simon	1:2dec995d53f8	313	if(_cmd(9, 0) != 0) {
simon	1:2dec995d53f8	314	fprintf(stderr, "Didn't get a response from the disk\n");
simon	1:2dec995d53f8	315	return 0;
simon	1:2dec995d53f8	316	}
simon	1:2dec995d53f8	317
simon	1:2dec995d53f8	318	char csd[16];
simon	1:2dec995d53f8	319	if(_read(csd, 16) != 0) {
simon	1:2dec995d53f8	320	fprintf(stderr, "Couldn't read csd response from disk\n");
simon	1:2dec995d53f8	321	return 0;
simon	1:2dec995d53f8	322	}
simon	1:2dec995d53f8	323
simon	1:2dec995d53f8	324	// csd_structure : csd[127:126]
simon	1:2dec995d53f8	325	// c_size : csd[73:62]
simon	1:2dec995d53f8	326	// c_size_mult : csd[49:47]
simon	1:2dec995d53f8	327	// read_bl_len : csd[83:80]
simon	1:2dec995d53f8	328
simon	1:2dec995d53f8	329	int csd_structure = ext_bits(csd, 127, 126);
simon	1:2dec995d53f8	330	int c_size = ext_bits(csd, 73, 62);
simon	1:2dec995d53f8	331	int c_size_mult = ext_bits(csd, 49, 47);
simon	1:2dec995d53f8	332	int read_bl_len = ext_bits(csd, 83, 80);
simon	1:2dec995d53f8	333
simon	1:2dec995d53f8	334	if(csd_structure != 0) {
simon	1:2dec995d53f8	335	fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures");
simon	1:2dec995d53f8	336	return 0;
simon	1:2dec995d53f8	337	}
simon	1:2dec995d53f8	338
simon	1:2dec995d53f8	339	int blocks = (c_size + 1) * (1 << (c_size_mult + 2));
simon	1:2dec995d53f8	340	int block_size = 1 << read_bl_len;
simon	1:2dec995d53f8	341
simon	1:2dec995d53f8	342	if(block_size != 512) {
simon	1:2dec995d53f8	343	fprintf(stderr, "This disk tastes funny! I only like 512-byte blocks");
simon	1:2dec995d53f8	344	return 0;
simon	1:2dec995d53f8	345	}
simon	1:2dec995d53f8	346
simon	1:2dec995d53f8	347	return blocks;
simon	1:2dec995d53f8	348	}

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	19 Nov 2009
Imports:	678
Forks:	1
Commits:	4
Dependents:	0
Dependencies:	1
Followers:	13

SDFileSystem.cpp@2:849162a1207f, 2009-12-14 (annotated)

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