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Simon Ford / Mbed 2 deprecated SDCardTest

SDFileSystem.cpp@3:68ef62208d4d, 2009-12-31 (annotated)

Committer:: simon
Date:: Thu Dec 31 15:11:08 2009 +0000
Revision:: 3:68ef62208d4d
Parent:: 2:849162a1207f

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	3:68ef62208d4d	3	*/
simon	3:68ef62208d4d	4
simon	3:68ef62208d4d	5	// VERY DRAFT CODE! Needs serious rework/refactoring
simon	3:68ef62208d4d	6
simon	3:68ef62208d4d	7	/* Introduction
simon	1:2dec995d53f8	8	* ------------
simon	1:2dec995d53f8	9	* SD and MMC cards support a number of interfaces, but common to them all
simon	1:2dec995d53f8	10	* is one based on SPI. This is the one I'm implmenting because it means
simon	1:2dec995d53f8	11	* it is much more portable even though not so performant, and we already
simon	1:2dec995d53f8	12	* have the mbed SPI Interface!
simon	1:2dec995d53f8	13	*
simon	1:2dec995d53f8	14	* The main reference I'm using is Chapter 7, "SPI Mode" of:
simon	1:2dec995d53f8	15	* http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
simon	1:2dec995d53f8	16	*
simon	1:2dec995d53f8	17	* SPI Startup
simon	1:2dec995d53f8	18	* -----------
simon	1:2dec995d53f8	19	* The SD card powers up in SD mode. The SPI interface mode is selected by
simon	1:2dec995d53f8	20	* asserting CS low and sending the reset command (CMD0). The card will
simon	1:2dec995d53f8	21	* respond with a (R1) response.
simon	1:2dec995d53f8	22	*
simon	1:2dec995d53f8	23	* CMD8 is optionally sent to determine the voltage range supported, and
simon	1:2dec995d53f8	24	* indirectly determine whether it is a version 1.x SD/non-SD card or
simon	1:2dec995d53f8	25	* version 2.x. I'll just ignore this for now.
simon	1:2dec995d53f8	26	*
simon	1:2dec995d53f8	27	* ACMD41 is repeatedly issued to initialise the card, until "in idle"
simon	1:2dec995d53f8	28	* (bit 0) of the R1 response goes to '0', indicating it is initialised.
simon	1:2dec995d53f8	29	*
simon	1:2dec995d53f8	30	* You should also indicate whether the host supports High Capicity cards,
simon	1:2dec995d53f8	31	* and check whether the card is high capacity - i'll also ignore this
simon	1:2dec995d53f8	32	*
simon	1:2dec995d53f8	33	* SPI Protocol
simon	1:2dec995d53f8	34	* ------------
simon	1:2dec995d53f8	35	* The SD SPI protocol is based on transactions made up of 8-bit words, with
simon	1:2dec995d53f8	36	* the host starting every bus transaction by asserting the CS signal low. The
simon	1:2dec995d53f8	37	* card always responds to commands, data blocks and errors.
simon	1:2dec995d53f8	38	*
simon	1:2dec995d53f8	39	* The protocol supports a CRC, but by default it is off (except for the
simon	1:2dec995d53f8	40	* first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
simon	1:2dec995d53f8	41	* I'll leave the CRC off I think!
simon	1:2dec995d53f8	42	*
simon	1:2dec995d53f8	43	* Standard capacity cards have variable data block sizes, whereas High
simon	1:2dec995d53f8	44	* Capacity cards fix the size of data block to 512 bytes. I'll therefore
simon	1:2dec995d53f8	45	* just always use the Standard Capacity cards with a block size of 512 bytes.
simon	1:2dec995d53f8	46	* This is set with CMD16.
simon	1:2dec995d53f8	47	*
simon	1:2dec995d53f8	48	* You can read and write single blocks (CMD17, CMD25) or multiple blocks
simon	1:2dec995d53f8	49	* (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
simon	1:2dec995d53f8	50	* the card gets a read command, it responds with a response token, and then
simon	1:2dec995d53f8	51	* a data token or an error.
simon	1:2dec995d53f8	52	*
simon	1:2dec995d53f8	53	* SPI Command Format
simon	1:2dec995d53f8	54	* ------------------
simon	1:2dec995d53f8	55	* Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
simon	1:2dec995d53f8	56	*
simon	1:2dec995d53f8	57	* +---------------+------------+------------+-----------+----------+--------------+
simon	1:2dec995d53f8	58	* \| 01 \| cmd[5:0] \| arg[31:24] \| arg[23:16] \| arg[15:8] \| arg[7:0] \| crc[6:0] \| 1 \|
simon	1:2dec995d53f8	59	* +---------------+------------+------------+-----------+----------+--------------+
simon	1:2dec995d53f8	60	*
simon	1:2dec995d53f8	61	* As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
simon	1:2dec995d53f8	62	*
simon	1:2dec995d53f8	63	* All Application Specific commands shall be preceded with APP_CMD (CMD55).
simon	1:2dec995d53f8	64	*
simon	1:2dec995d53f8	65	* SPI Response Format
simon	1:2dec995d53f8	66	* -------------------
simon	1:2dec995d53f8	67	* The main response format (R1) is a status byte (normally zero). Key flags:
simon	1:2dec995d53f8	68	* idle - 1 if the card is in an idle state/initialising
simon	1:2dec995d53f8	69	* cmd - 1 if an illegal command code was detected
simon	1:2dec995d53f8	70	*
simon	1:2dec995d53f8	71	* +-------------------------------------------------+
simon	1:2dec995d53f8	72	* R1 \| 0 \| arg \| addr \| seq \| crc \| cmd \| erase \| idle \|
simon	1:2dec995d53f8	73	* +-------------------------------------------------+
simon	1:2dec995d53f8	74	*
simon	1:2dec995d53f8	75	* R1b is the same, except it is followed by a busy signal (zeros) until
simon	1:2dec995d53f8	76	* the first non-zero byte when it is ready again.
simon	1:2dec995d53f8	77	*
simon	1:2dec995d53f8	78	* Data Response Token
simon	1:2dec995d53f8	79	* -------------------
simon	1:2dec995d53f8	80	* Every data block written to the card is acknowledged by a byte
simon	1:2dec995d53f8	81	* response token
simon	1:2dec995d53f8	82	*
simon	1:2dec995d53f8	83	* +----------------------+
simon	1:2dec995d53f8	84	* \| xxx \| 0 \| status \| 1 \|
simon	1:2dec995d53f8	85	* +----------------------+
simon	1:2dec995d53f8	86	* 010 - OK!
simon	1:2dec995d53f8	87	* 101 - CRC Error
simon	1:2dec995d53f8	88	* 110 - Write Error
simon	1:2dec995d53f8	89	*
simon	1:2dec995d53f8	90	* Single Block Read and Write
simon	1:2dec995d53f8	91	* ---------------------------
simon	1:2dec995d53f8	92	*
simon	1:2dec995d53f8	93	* Block transfers have a byte header, followed by the data, followed
simon	1:2dec995d53f8	94	* by a 16-bit CRC. In our case, the data will always be 512 bytes.
simon	1:2dec995d53f8	95	*
simon	1:2dec995d53f8	96	* +------+---------+---------+- - - -+---------+-----------+----------+
simon	1:2dec995d53f8	97	* \| 0xFE \| data[0] \| data[1] \| \| data[n] \| crc[15:8] \| crc[7:0] \|
simon	1:2dec995d53f8	98	* +------+---------+---------+- - - -+---------+-----------+----------+
simon	1:2dec995d53f8	99	*/
simon	1:2dec995d53f8	100
simon	1:2dec995d53f8	101	#include "SDFileSystem.h"
simon	1:2dec995d53f8	102
simon	1:2dec995d53f8	103	#define SD_COMMAND_TIMEOUT 5000
simon	1:2dec995d53f8	104
simon	1:2dec995d53f8	105	SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
simon	1:2dec995d53f8	106	FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
simon	1:2dec995d53f8	107	_cs = 1;
simon	1:2dec995d53f8	108	}
simon	1:2dec995d53f8	109
simon	2:849162a1207f	110	#define R1_IDLE_STATE (1 << 0)
simon	2:849162a1207f	111	#define R1_ERASE_RESET (1 << 1)
simon	2:849162a1207f	112	#define R1_ILLEGAL_COMMAND (1 << 2)
simon	2:849162a1207f	113	#define R1_COM_CRC_ERROR (1 << 3)
simon	2:849162a1207f	114	#define R1_ERASE_SEQUENCE_ERROR (1 << 4)
simon	2:849162a1207f	115	#define R1_ADDRESS_ERROR (1 << 5)
simon	2:849162a1207f	116	#define R1_PARAMETER_ERROR (1 << 6)
simon	2:849162a1207f	117
simon	3:68ef62208d4d	118	// Types
simon	3:68ef62208d4d	119	// - v1.x Standard Capacity
simon	3:68ef62208d4d	120	// - v2.x Standard Capacity
simon	3:68ef62208d4d	121	// - v2.x High Capacity
simon	3:68ef62208d4d	122	// - Not recognised as an SD Card
simon	1:2dec995d53f8	123
simon	3:68ef62208d4d	124	#define SDCARD_FAIL 0
simon	3:68ef62208d4d	125	#define SDCARD_V1 1
simon	3:68ef62208d4d	126	#define SDCARD_V2 2
simon	3:68ef62208d4d	127	#define SDCARD_V2HC 3
simon	3:68ef62208d4d	128
simon	3:68ef62208d4d	129	int SDFileSystem::initialise_card() {
simon	3:68ef62208d4d	130	// Set to 100kHz for initialisation, and clock card with cs = 1
simon	3:68ef62208d4d	131	_spi.frequency(100000);
simon	1:2dec995d53f8	132	_cs = 1;
simon	1:2dec995d53f8	133	for(int i=0; i<16; i++) {
simon	1:2dec995d53f8	134	_spi.write(0xFF);
simon	1:2dec995d53f8	135	}
simon	1:2dec995d53f8	136
simon	1:2dec995d53f8	137	// send CMD0, should return with all zeros except IDLE STATE set (bit 0)
simon	2:849162a1207f	138	if(_cmd(0, 0) != R1_IDLE_STATE) {
simon	2:849162a1207f	139	fprintf(stderr, "No disk, or could not put SD card in to SPI idle state\n");
simon	3:68ef62208d4d	140	return SDCARD_FAIL;
simon	1:2dec995d53f8	141	}
simon	2:849162a1207f	142
simon	3:68ef62208d4d	143	// send CMD8 to determine whther it is ver 2.x
simon	2:849162a1207f	144	int r = _cmd8();
simon	2:849162a1207f	145	if(r == R1_IDLE_STATE) {
simon	3:68ef62208d4d	146	return initialise_card_v2();
simon	2:849162a1207f	147	} else if(r == (R1_IDLE_STATE \| R1_ILLEGAL_COMMAND)) {
simon	3:68ef62208d4d	148	return initialise_card_v1();
simon	2:849162a1207f	149	} else {
simon	3:68ef62208d4d	150	fprintf(stderr, "Not in idle state after sending CMD8 (not an SD card?)\n");
simon	3:68ef62208d4d	151	return SDCARD_FAIL;
simon	2:849162a1207f	152	}
simon	3:68ef62208d4d	153	}
simon	3:68ef62208d4d	154
simon	3:68ef62208d4d	155	int SDFileSystem::initialise_card_v1() {
simon	3:68ef62208d4d	156	for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
simon	1:2dec995d53f8	157	_cmd(55, 0);
simon	3:68ef62208d4d	158	if(_cmd(41, 0) == 0) {
simon	3:68ef62208d4d	159	return SDCARD_V1;
simon	3:68ef62208d4d	160	}
simon	1:2dec995d53f8	161	}
simon	1:2dec995d53f8	162
simon	3:68ef62208d4d	163	fprintf(stderr, "Timeout waiting for v1.x card\n");
simon	3:68ef62208d4d	164	return SDCARD_FAIL;
simon	3:68ef62208d4d	165	}
simon	3:68ef62208d4d	166
simon	3:68ef62208d4d	167	int SDFileSystem::initialise_card_v2() {
simon	3:68ef62208d4d	168
simon	3:68ef62208d4d	169	for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
simon	3:68ef62208d4d	170	_cmd(55, 0);
simon	3:68ef62208d4d	171	if(_cmd(41, 0) == 0) {
simon	3:68ef62208d4d	172	_cmd58();
simon	3:68ef62208d4d	173	return SDCARD_V2;
simon	3:68ef62208d4d	174	}
simon	3:68ef62208d4d	175	}
simon	3:68ef62208d4d	176
simon	3:68ef62208d4d	177	fprintf(stderr, "Timeout waiting for v2.x card\n");
simon	3:68ef62208d4d	178	return SDCARD_FAIL;
simon	3:68ef62208d4d	179	}
simon	3:68ef62208d4d	180
simon	3:68ef62208d4d	181	int SDFileSystem::disk_initialize() {
simon	3:68ef62208d4d	182
simon	3:68ef62208d4d	183	int i = initialise_card();
simon	3:68ef62208d4d	184	// printf("init card = %d\n", i);
simon	3:68ef62208d4d	185	// printf("OK\n");
simon	2:849162a1207f	186
simon	1:2dec995d53f8	187	_sectors = _sd_sectors();
simon	1:2dec995d53f8	188
simon	1:2dec995d53f8	189	// Set block length to 512 (CMD16)
simon	1:2dec995d53f8	190	if(_cmd(16, 512) != 0) {
simon	3:68ef62208d4d	191	fprintf(stderr, "Set 512-byte block timed out\n");
simon	1:2dec995d53f8	192	return 1;
simon	1:2dec995d53f8	193	}
simon	1:2dec995d53f8	194
simon	1:2dec995d53f8	195	_spi.frequency(1000000); // Set to 1MHz for data transfer
simon	1:2dec995d53f8	196	return 0;
simon	1:2dec995d53f8	197	}
simon	1:2dec995d53f8	198
simon	1:2dec995d53f8	199	int SDFileSystem::disk_write(const char *buffer, int block_number) {
simon	1:2dec995d53f8	200	// set write address for single block (CMD24)
simon	1:2dec995d53f8	201	if(_cmd(24, block_number * 512) != 0) {
simon	1:2dec995d53f8	202	return 1;
simon	1:2dec995d53f8	203	}
simon	1:2dec995d53f8	204
simon	1:2dec995d53f8	205	// send the data block
simon	1:2dec995d53f8	206	_write(buffer, 512);
simon	1:2dec995d53f8	207	return 0;
simon	1:2dec995d53f8	208	}
simon	1:2dec995d53f8	209
simon	1:2dec995d53f8	210	int SDFileSystem::disk_read(char *buffer, int block_number) {
simon	1:2dec995d53f8	211	// set read address for single block (CMD17)
simon	1:2dec995d53f8	212	if(_cmd(17, block_number * 512) != 0) {
simon	1:2dec995d53f8	213	return 1;
simon	1:2dec995d53f8	214	}
simon	1:2dec995d53f8	215
simon	1:2dec995d53f8	216	// receive the data
simon	1:2dec995d53f8	217	_read(buffer, 512);
simon	1:2dec995d53f8	218	return 0;
simon	1:2dec995d53f8	219	}
simon	1:2dec995d53f8	220
simon	1:2dec995d53f8	221	int SDFileSystem::disk_status() { return 0; }
simon	1:2dec995d53f8	222	int SDFileSystem::disk_sync() { return 0; }
simon	1:2dec995d53f8	223	int SDFileSystem::disk_sectors() { return _sectors; }
simon	1:2dec995d53f8	224
simon	1:2dec995d53f8	225	// PRIVATE FUNCTIONS
simon	1:2dec995d53f8	226
simon	1:2dec995d53f8	227	int SDFileSystem::_cmd(int cmd, int arg) {
simon	1:2dec995d53f8	228	_cs = 0;
simon	1:2dec995d53f8	229
simon	1:2dec995d53f8	230	// send a command
simon	1:2dec995d53f8	231	_spi.write(0x40 \| cmd);
simon	1:2dec995d53f8	232	_spi.write(arg >> 24);
simon	1:2dec995d53f8	233	_spi.write(arg >> 16);
simon	1:2dec995d53f8	234	_spi.write(arg >> 8);
simon	1:2dec995d53f8	235	_spi.write(arg >> 0);
simon	1:2dec995d53f8	236	_spi.write(0x95);
simon	1:2dec995d53f8	237
simon	1:2dec995d53f8	238	// wait for the repsonse (response[7] == 0)
simon	1:2dec995d53f8	239	for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
simon	1:2dec995d53f8	240	int response = _spi.write(0xFF);
simon	1:2dec995d53f8	241	if(!(response & 0x80)) {
simon	1:2dec995d53f8	242	_cs = 1;
simon	1:2dec995d53f8	243	_spi.write(0xFF);
simon	1:2dec995d53f8	244	return response;
simon	1:2dec995d53f8	245	}
simon	1:2dec995d53f8	246	}
simon	1:2dec995d53f8	247	_cs = 1;
simon	1:2dec995d53f8	248	_spi.write(0xFF);
simon	1:2dec995d53f8	249	return -1; // timeout
simon	1:2dec995d53f8	250	}
simon	3:68ef62208d4d	251	int SDFileSystem::_cmdx(int cmd, int arg) {
simon	3:68ef62208d4d	252	_cs = 0;
simon	3:68ef62208d4d	253
simon	3:68ef62208d4d	254	// send a command
simon	3:68ef62208d4d	255	_spi.write(0x40 \| cmd);
simon	3:68ef62208d4d	256	_spi.write(arg >> 24);
simon	3:68ef62208d4d	257	_spi.write(arg >> 16);
simon	3:68ef62208d4d	258	_spi.write(arg >> 8);
simon	3:68ef62208d4d	259	_spi.write(arg >> 0);
simon	3:68ef62208d4d	260	_spi.write(0x95);
simon	3:68ef62208d4d	261
simon	3:68ef62208d4d	262	// wait for the repsonse (response[7] == 0)
simon	3:68ef62208d4d	263	for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
simon	3:68ef62208d4d	264	int response = _spi.write(0xFF);
simon	3:68ef62208d4d	265	if(!(response & 0x80)) {
simon	3:68ef62208d4d	266	return response;
simon	3:68ef62208d4d	267	}
simon	3:68ef62208d4d	268	}
simon	3:68ef62208d4d	269	_cs = 1;
simon	3:68ef62208d4d	270	_spi.write(0xFF);
simon	3:68ef62208d4d	271	return -1; // timeout
simon	3:68ef62208d4d	272	}
simon	3:68ef62208d4d	273
simon	3:68ef62208d4d	274
simon	3:68ef62208d4d	275	int SDFileSystem::_cmd58() {
simon	3:68ef62208d4d	276	_cs = 0;
simon	3:68ef62208d4d	277	int arg = 0;
simon	3:68ef62208d4d	278
simon	3:68ef62208d4d	279	// send a command
simon	3:68ef62208d4d	280	_spi.write(0x40 \| 58);
simon	3:68ef62208d4d	281	_spi.write(arg >> 24);
simon	3:68ef62208d4d	282	_spi.write(arg >> 16);
simon	3:68ef62208d4d	283	_spi.write(arg >> 8);
simon	3:68ef62208d4d	284	_spi.write(arg >> 0);
simon	3:68ef62208d4d	285	_spi.write(0x95);
simon	3:68ef62208d4d	286
simon	3:68ef62208d4d	287	// wait for the repsonse (response[7] == 0)
simon	3:68ef62208d4d	288	for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
simon	3:68ef62208d4d	289	int response = _spi.write(0xFF);
simon	3:68ef62208d4d	290	if(!(response & 0x80)) {
simon	3:68ef62208d4d	291	int ocr = _spi.write(0xFF) << 24;
simon	3:68ef62208d4d	292	ocr \|= _spi.write(0xFF) << 16;
simon	3:68ef62208d4d	293	ocr \|= _spi.write(0xFF) << 8;
simon	3:68ef62208d4d	294	ocr \|= _spi.write(0xFF) << 0;
simon	3:68ef62208d4d	295	// printf("OCR = 0x%08X\n", ocr);
simon	3:68ef62208d4d	296	_cs = 1;
simon	3:68ef62208d4d	297	_spi.write(0xFF);
simon	3:68ef62208d4d	298	return response;
simon	3:68ef62208d4d	299	}
simon	3:68ef62208d4d	300	}
simon	3:68ef62208d4d	301	_cs = 1;
simon	3:68ef62208d4d	302	_spi.write(0xFF);
simon	3:68ef62208d4d	303	return -1; // timeout
simon	3:68ef62208d4d	304	}
simon	1:2dec995d53f8	305
simon	2:849162a1207f	306	int SDFileSystem::_cmd8() {
simon	2:849162a1207f	307	_cs = 0;
simon	2:849162a1207f	308
simon	2:849162a1207f	309	// send a command
simon	2:849162a1207f	310	_spi.write(0x40 \| 8); // CMD8
simon	2:849162a1207f	311	_spi.write(0x00); // reserved
simon	2:849162a1207f	312	_spi.write(0x00); // reserved
simon	2:849162a1207f	313	_spi.write(0x01); // 3.3v
simon	2:849162a1207f	314	_spi.write(0xAA); // check pattern
simon	2:849162a1207f	315	_spi.write(0x87); // crc
simon	2:849162a1207f	316
simon	2:849162a1207f	317	// wait for the repsonse (response[7] == 0)
simon	2:849162a1207f	318	for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) {
simon	2:849162a1207f	319	char response[5];
simon	2:849162a1207f	320	response[0] = _spi.write(0xFF);
simon	2:849162a1207f	321	if(!(response[0] & 0x80)) {
simon	2:849162a1207f	322	for(int j=1; j<5; j++) {
simon	2:849162a1207f	323	response[i] = _spi.write(0xFF);
simon	2:849162a1207f	324	}
simon	2:849162a1207f	325	_cs = 1;
simon	2:849162a1207f	326	_spi.write(0xFF);
simon	2:849162a1207f	327	return response[0];
simon	2:849162a1207f	328	}
simon	2:849162a1207f	329	}
simon	2:849162a1207f	330	_cs = 1;
simon	2:849162a1207f	331	_spi.write(0xFF);
simon	2:849162a1207f	332	return -1; // timeout
simon	2:849162a1207f	333	}
simon	2:849162a1207f	334
simon	1:2dec995d53f8	335	int SDFileSystem::_read(char *buffer, int length) {
simon	1:2dec995d53f8	336	_cs = 0;
simon	1:2dec995d53f8	337
simon	1:2dec995d53f8	338	// read until start byte (0xFF)
simon	1:2dec995d53f8	339	while(_spi.write(0xFF) != 0xFE);
simon	1:2dec995d53f8	340
simon	1:2dec995d53f8	341	// read data
simon	1:2dec995d53f8	342	for(int i=0; i<length; i++) {
simon	1:2dec995d53f8	343	buffer[i] = _spi.write(0xFF);
simon	1:2dec995d53f8	344	}
simon	1:2dec995d53f8	345	_spi.write(0xFF); // checksum
simon	1:2dec995d53f8	346	_spi.write(0xFF);
simon	1:2dec995d53f8	347
simon	1:2dec995d53f8	348	_cs = 1;
simon	1:2dec995d53f8	349	_spi.write(0xFF);
simon	1:2dec995d53f8	350	return 0;
simon	1:2dec995d53f8	351	}
simon	1:2dec995d53f8	352
simon	1:2dec995d53f8	353	int SDFileSystem::_write(const char *buffer, int length) {
simon	1:2dec995d53f8	354	_cs = 0;
simon	1:2dec995d53f8	355
simon	1:2dec995d53f8	356	// indicate start of block
simon	1:2dec995d53f8	357	_spi.write(0xFE);
simon	1:2dec995d53f8	358
simon	1:2dec995d53f8	359	// write the data
simon	1:2dec995d53f8	360	for(int i=0; i<length; i++) {
simon	1:2dec995d53f8	361	_spi.write(buffer[i]);
simon	1:2dec995d53f8	362	}
simon	1:2dec995d53f8	363
simon	1:2dec995d53f8	364	// write the checksum
simon	1:2dec995d53f8	365	_spi.write(0xFF);
simon	1:2dec995d53f8	366	_spi.write(0xFF);
simon	1:2dec995d53f8	367
simon	1:2dec995d53f8	368	// check the repsonse token
simon	1:2dec995d53f8	369	if((_spi.write(0xFF) & 0x1F) != 0x05) {
simon	1:2dec995d53f8	370	_cs = 1;
simon	1:2dec995d53f8	371	_spi.write(0xFF);
simon	1:2dec995d53f8	372	return 1;
simon	1:2dec995d53f8	373	}
simon	1:2dec995d53f8	374
simon	1:2dec995d53f8	375	// wait for write to finish
simon	1:2dec995d53f8	376	while(_spi.write(0xFF) == 0);
simon	1:2dec995d53f8	377
simon	1:2dec995d53f8	378	_cs = 1;
simon	1:2dec995d53f8	379	_spi.write(0xFF);
simon	1:2dec995d53f8	380	return 0;
simon	1:2dec995d53f8	381	}
simon	1:2dec995d53f8	382
simon	1:2dec995d53f8	383	static int ext_bits(char *data, int msb, int lsb) {
simon	1:2dec995d53f8	384	int bits = 0;
simon	1:2dec995d53f8	385	int size = 1 + msb - lsb;
simon	1:2dec995d53f8	386	for(int i=0; i<size; i++) {
simon	1:2dec995d53f8	387	int position = lsb + i;
simon	1:2dec995d53f8	388	int byte = 15 - (position >> 3);
simon	1:2dec995d53f8	389	int bit = position & 0x7;
simon	1:2dec995d53f8	390	int value = (data[byte] >> bit) & 1;
simon	1:2dec995d53f8	391	bits \|= value << i;
simon	1:2dec995d53f8	392	}
simon	1:2dec995d53f8	393	return bits;
simon	1:2dec995d53f8	394	}
simon	1:2dec995d53f8	395
simon	1:2dec995d53f8	396	int SDFileSystem::_sd_sectors() {
simon	1:2dec995d53f8	397
simon	1:2dec995d53f8	398	// CMD9, Response R2 (R1 byte + 16-byte block read)
simon	3:68ef62208d4d	399	if(_cmdx(9, 0) != 0) {
simon	1:2dec995d53f8	400	fprintf(stderr, "Didn't get a response from the disk\n");
simon	1:2dec995d53f8	401	return 0;
simon	1:2dec995d53f8	402	}
simon	1:2dec995d53f8	403
simon	1:2dec995d53f8	404	char csd[16];
simon	1:2dec995d53f8	405	if(_read(csd, 16) != 0) {
simon	1:2dec995d53f8	406	fprintf(stderr, "Couldn't read csd response from disk\n");
simon	1:2dec995d53f8	407	return 0;
simon	1:2dec995d53f8	408	}
simon	1:2dec995d53f8	409
simon	1:2dec995d53f8	410	// csd_structure : csd[127:126]
simon	1:2dec995d53f8	411	// c_size : csd[73:62]
simon	1:2dec995d53f8	412	// c_size_mult : csd[49:47]
simon	3:68ef62208d4d	413	// read_bl_len : csd[83:80] - the maximum read block length
simon	1:2dec995d53f8	414
simon	1:2dec995d53f8	415	int csd_structure = ext_bits(csd, 127, 126);
simon	1:2dec995d53f8	416	int c_size = ext_bits(csd, 73, 62);
simon	1:2dec995d53f8	417	int c_size_mult = ext_bits(csd, 49, 47);
simon	1:2dec995d53f8	418	int read_bl_len = ext_bits(csd, 83, 80);
simon	3:68ef62208d4d	419
simon	3:68ef62208d4d	420	// printf("CSD_STRUCT = %d\n", csd_structure);
simon	1:2dec995d53f8	421
simon	1:2dec995d53f8	422	if(csd_structure != 0) {
simon	3:68ef62208d4d	423	fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n");
simon	1:2dec995d53f8	424	return 0;
simon	1:2dec995d53f8	425	}
simon	3:68ef62208d4d	426
simon	3:68ef62208d4d	427	// memory capacity = BLOCKNR * BLOCK_LEN
simon	3:68ef62208d4d	428	// where
simon	3:68ef62208d4d	429	// BLOCKNR = (C_SIZE+1) * MULT
simon	3:68ef62208d4d	430	// MULT = 2^(C_SIZE_MULT+2) (C_SIZE_MULT < 8)
simon	3:68ef62208d4d	431	// BLOCK_LEN = 2^READ_BL_LEN, (READ_BL_LEN < 12)
simon	1:2dec995d53f8	432
simon	3:68ef62208d4d	433	int block_len = 1 << read_bl_len;
simon	3:68ef62208d4d	434	int mult = 1 << (c_size_mult + 2);
simon	3:68ef62208d4d	435	int blocknr = (c_size + 1) * mult;
simon	3:68ef62208d4d	436	int capacity = blocknr * block_len;
simon	3:68ef62208d4d	437
simon	3:68ef62208d4d	438	int blocks = capacity / 512;
simon	3:68ef62208d4d	439
simon	1:2dec995d53f8	440	return blocks;
simon	1:2dec995d53f8	441	}

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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@3:68ef62208d4d, 2009-12-31 (annotated)

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