diags - test code for our MBED board

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test code for our MBED board

SDFileSystem.cpp@1:6877bb99aa17, 2011-05-04 (annotated)

Committer:: lolpcc
Date:: Wed May 04 08:30:52 2011 +0000
Revision:: 1:6877bb99aa17

Who changed what in which revision?

User	Revision	Line number	New contents of line
lolpcc	1:6877bb99aa17	1	/* mbed Microcontroller Library - SDFileSystem
lolpcc	1:6877bb99aa17	2	* Copyright (c) 2008-2009, sford
lolpcc	1:6877bb99aa17	3	*
lolpcc	1:6877bb99aa17	4	* Introduction
lolpcc	1:6877bb99aa17	5	* ------------
lolpcc	1:6877bb99aa17	6	* SD and MMC cards support a number of interfaces, but common to them all
lolpcc	1:6877bb99aa17	7	* is one based on SPI. This is the one I'm implmenting because it means
lolpcc	1:6877bb99aa17	8	* it is much more portable even though not so performant, and we already
lolpcc	1:6877bb99aa17	9	* have the mbed SPI Interface!
lolpcc	1:6877bb99aa17	10	*
lolpcc	1:6877bb99aa17	11	* The main reference I'm using is Chapter 7, "SPI Mode" of:
lolpcc	1:6877bb99aa17	12	* http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
lolpcc	1:6877bb99aa17	13	*
lolpcc	1:6877bb99aa17	14	* SPI Startup
lolpcc	1:6877bb99aa17	15	* -----------
lolpcc	1:6877bb99aa17	16	* The SD card powers up in SD mode. The SPI interface mode is selected by
lolpcc	1:6877bb99aa17	17	* asserting CS low and sending the reset command (CMD0). The card will
lolpcc	1:6877bb99aa17	18	* respond with a (R1) response.
lolpcc	1:6877bb99aa17	19	*
lolpcc	1:6877bb99aa17	20	* CMD8 is optionally sent to determine the voltage range supported, and
lolpcc	1:6877bb99aa17	21	* indirectly determine whether it is a version 1.x SD/non-SD card or
lolpcc	1:6877bb99aa17	22	* version 2.x. I'll just ignore this for now.
lolpcc	1:6877bb99aa17	23	*
lolpcc	1:6877bb99aa17	24	* ACMD41 is repeatedly issued to initialise the card, until "in idle"
lolpcc	1:6877bb99aa17	25	* (bit 0) of the R1 response goes to '0', indicating it is initialised.
lolpcc	1:6877bb99aa17	26	*
lolpcc	1:6877bb99aa17	27	* You should also indicate whether the host supports High Capicity cards,
lolpcc	1:6877bb99aa17	28	* and check whether the card is high capacity - i'll also ignore this
lolpcc	1:6877bb99aa17	29	*
lolpcc	1:6877bb99aa17	30	* SPI Protocol
lolpcc	1:6877bb99aa17	31	* ------------
lolpcc	1:6877bb99aa17	32	* The SD SPI protocol is based on transactions made up of 8-bit words, with
lolpcc	1:6877bb99aa17	33	* the host starting every bus transaction by asserting the CS signal low. The
lolpcc	1:6877bb99aa17	34	* card always responds to commands, data blocks and errors.
lolpcc	1:6877bb99aa17	35	*
lolpcc	1:6877bb99aa17	36	* The protocol supports a CRC, but by default it is off (except for the
lolpcc	1:6877bb99aa17	37	* first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
lolpcc	1:6877bb99aa17	38	* I'll leave the CRC off I think!
lolpcc	1:6877bb99aa17	39	*
lolpcc	1:6877bb99aa17	40	* Standard capacity cards have variable data block sizes, whereas High
lolpcc	1:6877bb99aa17	41	* Capacity cards fix the size of data block to 512 bytes. I'll therefore
lolpcc	1:6877bb99aa17	42	* just always use the Standard Capacity cards with a block size of 512 bytes.
lolpcc	1:6877bb99aa17	43	* This is set with CMD16.
lolpcc	1:6877bb99aa17	44	*
lolpcc	1:6877bb99aa17	45	* You can read and write single blocks (CMD17, CMD25) or multiple blocks
lolpcc	1:6877bb99aa17	46	* (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
lolpcc	1:6877bb99aa17	47	* the card gets a read command, it responds with a response token, and then
lolpcc	1:6877bb99aa17	48	* a data token or an error.
lolpcc	1:6877bb99aa17	49	*
lolpcc	1:6877bb99aa17	50	* SPI Command Format
lolpcc	1:6877bb99aa17	51	* ------------------
lolpcc	1:6877bb99aa17	52	* Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
lolpcc	1:6877bb99aa17	53	*
lolpcc	1:6877bb99aa17	54	* +---------------+------------+------------+-----------+----------+--------------+
lolpcc	1:6877bb99aa17	55	* \| 01 \| cmd[5:0] \| arg[31:24] \| arg[23:16] \| arg[15:8] \| arg[7:0] \| crc[6:0] \| 1 \|
lolpcc	1:6877bb99aa17	56	* +---------------+------------+------------+-----------+----------+--------------+
lolpcc	1:6877bb99aa17	57	*
lolpcc	1:6877bb99aa17	58	* As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
lolpcc	1:6877bb99aa17	59	*
lolpcc	1:6877bb99aa17	60	* All Application Specific commands shall be preceded with APP_CMD (CMD55).
lolpcc	1:6877bb99aa17	61	*
lolpcc	1:6877bb99aa17	62	* SPI Response Format
lolpcc	1:6877bb99aa17	63	* -------------------
lolpcc	1:6877bb99aa17	64	* The main response format (R1) is a status byte (normally zero). Key flags:
lolpcc	1:6877bb99aa17	65	* idle - 1 if the card is in an idle state/initialising
lolpcc	1:6877bb99aa17	66	* cmd - 1 if an illegal command code was detected
lolpcc	1:6877bb99aa17	67	*
lolpcc	1:6877bb99aa17	68	* +-------------------------------------------------+
lolpcc	1:6877bb99aa17	69	* R1 \| 0 \| arg \| addr \| seq \| crc \| cmd \| erase \| idle \|
lolpcc	1:6877bb99aa17	70	* +-------------------------------------------------+
lolpcc	1:6877bb99aa17	71	*
lolpcc	1:6877bb99aa17	72	* R1b is the same, except it is followed by a busy signal (zeros) until
lolpcc	1:6877bb99aa17	73	* the first non-zero byte when it is ready again.
lolpcc	1:6877bb99aa17	74	*
lolpcc	1:6877bb99aa17	75	* Data Response Token
lolpcc	1:6877bb99aa17	76	* -------------------
lolpcc	1:6877bb99aa17	77	* Every data block written to the card is acknowledged by a byte
lolpcc	1:6877bb99aa17	78	* response token
lolpcc	1:6877bb99aa17	79	*
lolpcc	1:6877bb99aa17	80	* +----------------------+
lolpcc	1:6877bb99aa17	81	* \| xxx \| 0 \| status \| 1 \|
lolpcc	1:6877bb99aa17	82	* +----------------------+
lolpcc	1:6877bb99aa17	83	* 010 - OK!
lolpcc	1:6877bb99aa17	84	* 101 - CRC Error
lolpcc	1:6877bb99aa17	85	* 110 - Write Error
lolpcc	1:6877bb99aa17	86	*
lolpcc	1:6877bb99aa17	87	* Single Block Read and Write
lolpcc	1:6877bb99aa17	88	* ---------------------------
lolpcc	1:6877bb99aa17	89	*
lolpcc	1:6877bb99aa17	90	* Block transfers have a byte header, followed by the data, followed
lolpcc	1:6877bb99aa17	91	* by a 16-bit CRC. In our case, the data will always be 512 bytes.
lolpcc	1:6877bb99aa17	92	*
lolpcc	1:6877bb99aa17	93	* +------+---------+---------+- - - -+---------+-----------+----------+
lolpcc	1:6877bb99aa17	94	* \| 0xFE \| data[0] \| data[1] \| \| data[n] \| crc[15:8] \| crc[7:0] \|
lolpcc	1:6877bb99aa17	95	* +------+---------+---------+- - - -+---------+-----------+----------+
lolpcc	1:6877bb99aa17	96	*/
lolpcc	1:6877bb99aa17	97
lolpcc	1:6877bb99aa17	98	#include "SDFileSystem.h"
lolpcc	1:6877bb99aa17	99
lolpcc	1:6877bb99aa17	100	#define SD_COMMAND_TIMEOUT 5000
lolpcc	1:6877bb99aa17	101
lolpcc	1:6877bb99aa17	102	SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
lolpcc	1:6877bb99aa17	103	FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
lolpcc	1:6877bb99aa17	104	_cs = 1;
lolpcc	1:6877bb99aa17	105	}
lolpcc	1:6877bb99aa17	106
lolpcc	1:6877bb99aa17	107	int SDFileSystem::disk_initialize() {
lolpcc	1:6877bb99aa17	108
lolpcc	1:6877bb99aa17	109	_spi.frequency(100000); // Set to 100kHz for initialisation
lolpcc	1:6877bb99aa17	110
lolpcc	1:6877bb99aa17	111	// Initialise the card by clocking it a bit (cs = 1)
lolpcc	1:6877bb99aa17	112	for(int i=0; i<16; i++) {
lolpcc	1:6877bb99aa17	113	_spi.write(0xFF);
lolpcc	1:6877bb99aa17	114	}
lolpcc	1:6877bb99aa17	115
lolpcc	1:6877bb99aa17	116	// send CMD0, should return with all zeros except IDLE STATE set (bit 0)
lolpcc	1:6877bb99aa17	117	if(_cmd(0, 0) != 0x01) {
lolpcc	1:6877bb99aa17	118	fprintf(stderr, "Not in idle state\n");
lolpcc	1:6877bb99aa17	119	return 1;
lolpcc	1:6877bb99aa17	120	}
lolpcc	1:6877bb99aa17	121
lolpcc	1:6877bb99aa17	122	// ACMD41 to give host capacity support (repeat until not busy)
lolpcc	1:6877bb99aa17	123	// ACMD41 is application specific command, so we send APP_CMD (CMD55) beforehand
lolpcc	1:6877bb99aa17	124	for(int i=0;; i++) {
lolpcc	1:6877bb99aa17	125	_cmd(55, 0);
lolpcc	1:6877bb99aa17	126	int response = _cmd(41, 0);
lolpcc	1:6877bb99aa17	127	if(response == 0) {
lolpcc	1:6877bb99aa17	128	break;
lolpcc	1:6877bb99aa17	129	} else if(i > SD_COMMAND_TIMEOUT) {
lolpcc	1:6877bb99aa17	130	fprintf(stderr, "Timeout waiting for card\n");
lolpcc	1:6877bb99aa17	131	return 1;
lolpcc	1:6877bb99aa17	132	}
lolpcc	1:6877bb99aa17	133	}
lolpcc	1:6877bb99aa17	134
lolpcc	1:6877bb99aa17	135	_sectors = _sd_sectors();
lolpcc	1:6877bb99aa17	136
lolpcc	1:6877bb99aa17	137	// Set block length to 512 (CMD16)
lolpcc	1:6877bb99aa17	138	if(_cmd(16, 512) != 0) {
lolpcc	1:6877bb99aa17	139	fprintf(stderr, "Set block timeout\n");
lolpcc	1:6877bb99aa17	140	return 1;
lolpcc	1:6877bb99aa17	141	}
lolpcc	1:6877bb99aa17	142
lolpcc	1:6877bb99aa17	143	_spi.frequency(1000000); // Set to 1MHz for data transfer
lolpcc	1:6877bb99aa17	144	return 0;
lolpcc	1:6877bb99aa17	145	}
lolpcc	1:6877bb99aa17	146
lolpcc	1:6877bb99aa17	147	int SDFileSystem::disk_write(const char *buffer, int block_number) {
lolpcc	1:6877bb99aa17	148	// set write address for single block (CMD24)
lolpcc	1:6877bb99aa17	149	if(_cmd(24, block_number * 512) != 0) {
lolpcc	1:6877bb99aa17	150	return 1;
lolpcc	1:6877bb99aa17	151	}
lolpcc	1:6877bb99aa17	152
lolpcc	1:6877bb99aa17	153	// send the data block
lolpcc	1:6877bb99aa17	154	_write(buffer, 512);
lolpcc	1:6877bb99aa17	155	return 0;
lolpcc	1:6877bb99aa17	156	}
lolpcc	1:6877bb99aa17	157
lolpcc	1:6877bb99aa17	158	int SDFileSystem::disk_read(char *buffer, int block_number) {
lolpcc	1:6877bb99aa17	159	// set read address for single block (CMD17)
lolpcc	1:6877bb99aa17	160	if(_cmd(17, block_number * 512) != 0) {
lolpcc	1:6877bb99aa17	161	return 1;
lolpcc	1:6877bb99aa17	162	}
lolpcc	1:6877bb99aa17	163
lolpcc	1:6877bb99aa17	164	// receive the data
lolpcc	1:6877bb99aa17	165	_read(buffer, 512);
lolpcc	1:6877bb99aa17	166	return 0;
lolpcc	1:6877bb99aa17	167	}
lolpcc	1:6877bb99aa17	168
lolpcc	1:6877bb99aa17	169	int SDFileSystem::disk_status() { return 0; }
lolpcc	1:6877bb99aa17	170	int SDFileSystem::disk_sync() { return 0; }
lolpcc	1:6877bb99aa17	171	int SDFileSystem::disk_sectors() { return _sectors; }
lolpcc	1:6877bb99aa17	172
lolpcc	1:6877bb99aa17	173	// PRIVATE FUNCTIONS
lolpcc	1:6877bb99aa17	174
lolpcc	1:6877bb99aa17	175	int SDFileSystem::_cmd(int cmd, int arg) {
lolpcc	1:6877bb99aa17	176	_cs = 0;
lolpcc	1:6877bb99aa17	177
lolpcc	1:6877bb99aa17	178	// send a command
lolpcc	1:6877bb99aa17	179	_spi.write(0x40 \| cmd);
lolpcc	1:6877bb99aa17	180	_spi.write(arg >> 24);
lolpcc	1:6877bb99aa17	181	_spi.write(arg >> 16);
lolpcc	1:6877bb99aa17	182	_spi.write(arg >> 8);
lolpcc	1:6877bb99aa17	183	_spi.write(arg >> 0);
lolpcc	1:6877bb99aa17	184	_spi.write(0x95);
lolpcc	1:6877bb99aa17	185
lolpcc	1:6877bb99aa17	186	// wait for the repsonse (response[7] == 0)
lolpcc	1:6877bb99aa17	187	for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
lolpcc	1:6877bb99aa17	188	int response = _spi.write(0xFF);
lolpcc	1:6877bb99aa17	189	if(!(response & 0x80)) {
lolpcc	1:6877bb99aa17	190	_cs = 1;
lolpcc	1:6877bb99aa17	191	return response;
lolpcc	1:6877bb99aa17	192	}
lolpcc	1:6877bb99aa17	193	}
lolpcc	1:6877bb99aa17	194	_cs = 1;
lolpcc	1:6877bb99aa17	195	return -1; // timeout
lolpcc	1:6877bb99aa17	196	}
lolpcc	1:6877bb99aa17	197
lolpcc	1:6877bb99aa17	198	int SDFileSystem::_read(char *buffer, int length) {
lolpcc	1:6877bb99aa17	199	_cs = 0;
lolpcc	1:6877bb99aa17	200
lolpcc	1:6877bb99aa17	201	// read until start byte (0xFF)
lolpcc	1:6877bb99aa17	202	while(_spi.write(0xFF) != 0xFE);
lolpcc	1:6877bb99aa17	203
lolpcc	1:6877bb99aa17	204	// read data
lolpcc	1:6877bb99aa17	205	for(int i=0; i<length; i++) {
lolpcc	1:6877bb99aa17	206	buffer[i] = _spi.write(0xFF);
lolpcc	1:6877bb99aa17	207	}
lolpcc	1:6877bb99aa17	208	_spi.write(0xFF); // checksum
lolpcc	1:6877bb99aa17	209	_spi.write(0xFF);
lolpcc	1:6877bb99aa17	210
lolpcc	1:6877bb99aa17	211	_cs = 1;
lolpcc	1:6877bb99aa17	212	return 0;
lolpcc	1:6877bb99aa17	213	}
lolpcc	1:6877bb99aa17	214
lolpcc	1:6877bb99aa17	215	int SDFileSystem::_write(const char *buffer, int length) {
lolpcc	1:6877bb99aa17	216	_cs = 0;
lolpcc	1:6877bb99aa17	217
lolpcc	1:6877bb99aa17	218	// indicate start of block
lolpcc	1:6877bb99aa17	219	_spi.write(0xFE);
lolpcc	1:6877bb99aa17	220
lolpcc	1:6877bb99aa17	221	// write the data
lolpcc	1:6877bb99aa17	222	for(int i=0; i<length; i++) {
lolpcc	1:6877bb99aa17	223	_spi.write(buffer[i]);
lolpcc	1:6877bb99aa17	224	}
lolpcc	1:6877bb99aa17	225
lolpcc	1:6877bb99aa17	226	// write the checksum
lolpcc	1:6877bb99aa17	227	_spi.write(0xFF);
lolpcc	1:6877bb99aa17	228	_spi.write(0xFF);
lolpcc	1:6877bb99aa17	229
lolpcc	1:6877bb99aa17	230	// check the repsonse token
lolpcc	1:6877bb99aa17	231	if((_spi.write(0xFF) & 0x1F) != 0x05) {
lolpcc	1:6877bb99aa17	232	_cs = 1;
lolpcc	1:6877bb99aa17	233	return 1;
lolpcc	1:6877bb99aa17	234	}
lolpcc	1:6877bb99aa17	235
lolpcc	1:6877bb99aa17	236	// wait for write to finish
lolpcc	1:6877bb99aa17	237	while(_spi.write(0xFF) == 0);
lolpcc	1:6877bb99aa17	238
lolpcc	1:6877bb99aa17	239	_cs = 1;
lolpcc	1:6877bb99aa17	240	return 0;
lolpcc	1:6877bb99aa17	241	}
lolpcc	1:6877bb99aa17	242
lolpcc	1:6877bb99aa17	243	static int ext_bits(char *data, int msb, int lsb) {
lolpcc	1:6877bb99aa17	244	int bits = 0;
lolpcc	1:6877bb99aa17	245	int size = 1 + msb - lsb;
lolpcc	1:6877bb99aa17	246	for(int i=0; i<size; i++) {
lolpcc	1:6877bb99aa17	247	int position = lsb + i;
lolpcc	1:6877bb99aa17	248	int byte = 15 - (position >> 3);
lolpcc	1:6877bb99aa17	249	int bit = position & 0x7;
lolpcc	1:6877bb99aa17	250	int value = (data[byte] >> bit) & 1;
lolpcc	1:6877bb99aa17	251	bits \|= value << i;
lolpcc	1:6877bb99aa17	252	}
lolpcc	1:6877bb99aa17	253	return bits;
lolpcc	1:6877bb99aa17	254	}
lolpcc	1:6877bb99aa17	255
lolpcc	1:6877bb99aa17	256	int SDFileSystem::_sd_sectors() {
lolpcc	1:6877bb99aa17	257
lolpcc	1:6877bb99aa17	258	// CMD9, Response R2 (R1 byte + 16-byte block read)
lolpcc	1:6877bb99aa17	259	if(_cmd(9, 0) != 0) {
lolpcc	1:6877bb99aa17	260	fprintf(stderr, "Didn't get a response from the disk\n");
lolpcc	1:6877bb99aa17	261	return 0;
lolpcc	1:6877bb99aa17	262	}
lolpcc	1:6877bb99aa17	263
lolpcc	1:6877bb99aa17	264	char csd[16];
lolpcc	1:6877bb99aa17	265	if(_read(csd, 16) != 0) {
lolpcc	1:6877bb99aa17	266	fprintf(stderr, "Couldn't read csd response from disk\n");
lolpcc	1:6877bb99aa17	267	return 0;
lolpcc	1:6877bb99aa17	268	}
lolpcc	1:6877bb99aa17	269
lolpcc	1:6877bb99aa17	270	// csd_structure : csd[127:126]
lolpcc	1:6877bb99aa17	271	// c_size : csd[73:62]
lolpcc	1:6877bb99aa17	272	// c_size_mult : csd[49:47]
lolpcc	1:6877bb99aa17	273	// read_bl_len : csd[83:80]
lolpcc	1:6877bb99aa17	274
lolpcc	1:6877bb99aa17	275	int csd_structure = ext_bits(csd, 127, 126);
lolpcc	1:6877bb99aa17	276	int c_size = ext_bits(csd, 73, 62);
lolpcc	1:6877bb99aa17	277	int c_size_mult = ext_bits(csd, 49, 47);
lolpcc	1:6877bb99aa17	278	int read_bl_len = ext_bits(csd, 83, 80);
lolpcc	1:6877bb99aa17	279
lolpcc	1:6877bb99aa17	280	if(csd_structure != 0) {
lolpcc	1:6877bb99aa17	281	fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures");
lolpcc	1:6877bb99aa17	282	return 0;
lolpcc	1:6877bb99aa17	283	}
lolpcc	1:6877bb99aa17	284
lolpcc	1:6877bb99aa17	285	int blocks = (c_size + 1) * (1 << (c_size_mult + 2));
lolpcc	1:6877bb99aa17	286	int block_size = 1 << read_bl_len;
lolpcc	1:6877bb99aa17	287
lolpcc	1:6877bb99aa17	288	if(block_size != 512) {
lolpcc	1:6877bb99aa17	289	fprintf(stderr, "This disk tastes funny! I only like 512-byte blocks");
lolpcc	1:6877bb99aa17	290	return 0;
lolpcc	1:6877bb99aa17	291	}
lolpcc	1:6877bb99aa17	292
lolpcc	1:6877bb99aa17	293	return blocks;
lolpcc	1:6877bb99aa17	294	}

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	12 Jan 2010
Imports:	24
Forks:	0
Commits:	2
Dependents:	0
Dependencies:	2
Followers:	3

SDFileSystem.cpp@1:6877bb99aa17, 2011-05-04 (annotated)

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