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Example of HTTPServer with additional features: * SNTPClient, DST rules * Link status indication * Local or SDCard-based WebServer * RPC-able class * Static and Dynamic HTML page

Dependencies: mbed

SDFileSystem.cpp@2:360fda42fefd, 2010-01-12 (annotated)

Committer:: iva2k
Date:: Tue Jan 12 07:41:55 2010 +0000
Revision:: 2:360fda42fefd
Parent:: 0:886e4b3119ad

Who changed what in which revision?

User	Revision	Line number	New contents of line
iva2k	0:886e4b3119ad	1	/* mbed Microcontroller Library - SDFileSystem
iva2k	0:886e4b3119ad	2	* Copyright (c) 2008-2009, sford
iva2k	0:886e4b3119ad	3	*
iva2k	0:886e4b3119ad	4	* Introduction
iva2k	0:886e4b3119ad	5	* ------------
iva2k	0:886e4b3119ad	6	* SD and MMC cards support a number of interfaces, but common to them all
iva2k	0:886e4b3119ad	7	* is one based on SPI. This is the one I'm implmenting because it means
iva2k	0:886e4b3119ad	8	* it is much more portable even though not so performant, and we already
iva2k	0:886e4b3119ad	9	* have the mbed SPI Interface!
iva2k	0:886e4b3119ad	10	*
iva2k	0:886e4b3119ad	11	* The main reference I'm using is Chapter 7, "SPI Mode" of:
iva2k	0:886e4b3119ad	12	* http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
iva2k	0:886e4b3119ad	13	*
iva2k	0:886e4b3119ad	14	* SPI Startup
iva2k	0:886e4b3119ad	15	* -----------
iva2k	0:886e4b3119ad	16	* The SD card powers up in SD mode. The SPI interface mode is selected by
iva2k	0:886e4b3119ad	17	* asserting CS low and sending the reset command (CMD0). The card will
iva2k	0:886e4b3119ad	18	* respond with a (R1) response.
iva2k	0:886e4b3119ad	19	*
iva2k	0:886e4b3119ad	20	* CMD8 is optionally sent to determine the voltage range supported, and
iva2k	0:886e4b3119ad	21	* indirectly determine whether it is a version 1.x SD/non-SD card or
iva2k	0:886e4b3119ad	22	* version 2.x. I'll just ignore this for now.
iva2k	0:886e4b3119ad	23	*
iva2k	0:886e4b3119ad	24	* ACMD41 is repeatedly issued to initialise the card, until "in idle"
iva2k	0:886e4b3119ad	25	* (bit 0) of the R1 response goes to '0', indicating it is initialised.
iva2k	0:886e4b3119ad	26	*
iva2k	0:886e4b3119ad	27	* You should also indicate whether the host supports High Capicity cards,
iva2k	0:886e4b3119ad	28	* and check whether the card is high capacity - i'll also ignore this
iva2k	0:886e4b3119ad	29	*
iva2k	0:886e4b3119ad	30	* SPI Protocol
iva2k	0:886e4b3119ad	31	* ------------
iva2k	0:886e4b3119ad	32	* The SD SPI protocol is based on transactions made up of 8-bit words, with
iva2k	0:886e4b3119ad	33	* the host starting every bus transaction by asserting the CS signal low. The
iva2k	0:886e4b3119ad	34	* card always responds to commands, data blocks and errors.
iva2k	0:886e4b3119ad	35	*
iva2k	0:886e4b3119ad	36	* The protocol supports a CRC, but by default it is off (except for the
iva2k	0:886e4b3119ad	37	* first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
iva2k	0:886e4b3119ad	38	* I'll leave the CRC off I think!
iva2k	0:886e4b3119ad	39	*
iva2k	0:886e4b3119ad	40	* Standard capacity cards have variable data block sizes, whereas High
iva2k	0:886e4b3119ad	41	* Capacity cards fix the size of data block to 512 bytes. I'll therefore
iva2k	0:886e4b3119ad	42	* just always use the Standard Capacity cards with a block size of 512 bytes.
iva2k	0:886e4b3119ad	43	* This is set with CMD16.
iva2k	0:886e4b3119ad	44	*
iva2k	0:886e4b3119ad	45	* You can read and write single blocks (CMD17, CMD25) or multiple blocks
iva2k	0:886e4b3119ad	46	* (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
iva2k	0:886e4b3119ad	47	* the card gets a read command, it responds with a response token, and then
iva2k	0:886e4b3119ad	48	* a data token or an error.
iva2k	0:886e4b3119ad	49	*
iva2k	0:886e4b3119ad	50	* SPI Command Format
iva2k	0:886e4b3119ad	51	* ------------------
iva2k	0:886e4b3119ad	52	* Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
iva2k	0:886e4b3119ad	53	*
iva2k	0:886e4b3119ad	54	* +---------------+------------+------------+-----------+----------+--------------+
iva2k	0:886e4b3119ad	55	* \| 01 \| cmd[5:0] \| arg[31:24] \| arg[23:16] \| arg[15:8] \| arg[7:0] \| crc[6:0] \| 1 \|
iva2k	0:886e4b3119ad	56	* +---------------+------------+------------+-----------+----------+--------------+
iva2k	0:886e4b3119ad	57	*
iva2k	0:886e4b3119ad	58	* As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
iva2k	0:886e4b3119ad	59	*
iva2k	0:886e4b3119ad	60	* All Application Specific commands shall be preceded with APP_CMD (CMD55).
iva2k	0:886e4b3119ad	61	*
iva2k	0:886e4b3119ad	62	* SPI Response Format
iva2k	0:886e4b3119ad	63	* -------------------
iva2k	0:886e4b3119ad	64	* The main response format (R1) is a status byte (normally zero). Key flags:
iva2k	0:886e4b3119ad	65	* idle - 1 if the card is in an idle state/initialising
iva2k	0:886e4b3119ad	66	* cmd - 1 if an illegal command code was detected
iva2k	0:886e4b3119ad	67	*
iva2k	0:886e4b3119ad	68	* +-------------------------------------------------+
iva2k	0:886e4b3119ad	69	* R1 \| 0 \| arg \| addr \| seq \| crc \| cmd \| erase \| idle \|
iva2k	0:886e4b3119ad	70	* +-------------------------------------------------+
iva2k	0:886e4b3119ad	71	*
iva2k	0:886e4b3119ad	72	* R1b is the same, except it is followed by a busy signal (zeros) until
iva2k	0:886e4b3119ad	73	* the first non-zero byte when it is ready again.
iva2k	0:886e4b3119ad	74	*
iva2k	0:886e4b3119ad	75	* Data Response Token
iva2k	0:886e4b3119ad	76	* -------------------
iva2k	0:886e4b3119ad	77	* Every data block written to the card is acknowledged by a byte
iva2k	0:886e4b3119ad	78	* response token
iva2k	0:886e4b3119ad	79	*
iva2k	0:886e4b3119ad	80	* +----------------------+
iva2k	0:886e4b3119ad	81	* \| xxx \| 0 \| status \| 1 \|
iva2k	0:886e4b3119ad	82	* +----------------------+
iva2k	0:886e4b3119ad	83	* 010 - OK!
iva2k	0:886e4b3119ad	84	* 101 - CRC Error
iva2k	0:886e4b3119ad	85	* 110 - Write Error
iva2k	0:886e4b3119ad	86	*
iva2k	0:886e4b3119ad	87	* Single Block Read and Write
iva2k	0:886e4b3119ad	88	* ---------------------------
iva2k	0:886e4b3119ad	89	*
iva2k	0:886e4b3119ad	90	* Block transfers have a byte header, followed by the data, followed
iva2k	0:886e4b3119ad	91	* by a 16-bit CRC. In our case, the data will always be 512 bytes.
iva2k	0:886e4b3119ad	92	*
iva2k	0:886e4b3119ad	93	* +------+---------+---------+- - - -+---------+-----------+----------+
iva2k	0:886e4b3119ad	94	* \| 0xFE \| data[0] \| data[1] \| \| data[n] \| crc[15:8] \| crc[7:0] \|
iva2k	0:886e4b3119ad	95	* +------+---------+---------+- - - -+---------+-----------+----------+
iva2k	0:886e4b3119ad	96	*/
iva2k	0:886e4b3119ad	97
iva2k	0:886e4b3119ad	98	#include "SDFileSystem.h"
iva2k	0:886e4b3119ad	99
iva2k	0:886e4b3119ad	100	#define SD_COMMAND_TIMEOUT 5000
iva2k	0:886e4b3119ad	101
iva2k	0:886e4b3119ad	102	//#define CR "\n"
iva2k	0:886e4b3119ad	103	#define CR "\r\n"
iva2k	0:886e4b3119ad	104
iva2k	0:886e4b3119ad	105	SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
iva2k	0:886e4b3119ad	106	FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
iva2k	0:886e4b3119ad	107	_cs = 1;
iva2k	0:886e4b3119ad	108	}
iva2k	0:886e4b3119ad	109
iva2k	0:886e4b3119ad	110	#define R1_IDLE_STATE (1 << 0)
iva2k	0:886e4b3119ad	111	#define R1_ERASE_RESET (1 << 1)
iva2k	0:886e4b3119ad	112	#define R1_ILLEGAL_COMMAND (1 << 2)
iva2k	0:886e4b3119ad	113	#define R1_COM_CRC_ERROR (1 << 3)
iva2k	0:886e4b3119ad	114	#define R1_ERASE_SEQUENCE_ERROR (1 << 4)
iva2k	0:886e4b3119ad	115	#define R1_ADDRESS_ERROR (1 << 5)
iva2k	0:886e4b3119ad	116	#define R1_PARAMETER_ERROR (1 << 6)
iva2k	0:886e4b3119ad	117
iva2k	0:886e4b3119ad	118	int SDFileSystem::disk_initialize() {
iva2k	0:886e4b3119ad	119
iva2k	0:886e4b3119ad	120	_spi.frequency(100000); // Set to 100kHz for initialisation
iva2k	0:886e4b3119ad	121
iva2k	0:886e4b3119ad	122	// Initialise the card by clocking it a bit (cs = 1)
iva2k	0:886e4b3119ad	123	_cs = 1;
iva2k	0:886e4b3119ad	124	for(int i=0; i<16; i++) {
iva2k	0:886e4b3119ad	125	_spi.write(0xFF);
iva2k	0:886e4b3119ad	126	}
iva2k	0:886e4b3119ad	127
iva2k	0:886e4b3119ad	128	// send CMD0, should return with all zeros except IDLE STATE set (bit 0)
iva2k	0:886e4b3119ad	129	if(_cmd(0, 0) != R1_IDLE_STATE) {
iva2k	0:886e4b3119ad	130	fprintf(stderr, "No disk, or could not put SD card into SPI idle state" CR);
iva2k	0:886e4b3119ad	131	return 1;
iva2k	0:886e4b3119ad	132	}
iva2k	0:886e4b3119ad	133
iva2k	0:886e4b3119ad	134	int r = _cmd8();
iva2k	0:886e4b3119ad	135	if(r == R1_IDLE_STATE) {
iva2k	0:886e4b3119ad	136	printf("SD version 2.x" CR);
iva2k	0:886e4b3119ad	137	} else if(r == (R1_IDLE_STATE \| R1_ILLEGAL_COMMAND)) {
iva2k	0:886e4b3119ad	138	printf("SD version 1.x" CR);
iva2k	0:886e4b3119ad	139	} else {
iva2k	0:886e4b3119ad	140	error("Unknown SD version" CR);
iva2k	0:886e4b3119ad	141	}
iva2k	0:886e4b3119ad	142
iva2k	0:886e4b3119ad	143	// ACMD41 to give host capacity support (repeat until not busy)
iva2k	0:886e4b3119ad	144	// ACMD41 is application specific command, so we send APP_CMD (CMD55) beforehand
iva2k	0:886e4b3119ad	145	for(int i=0;; i++) {
iva2k	0:886e4b3119ad	146	_cmd(55, 0);
iva2k	0:886e4b3119ad	147	int response = _cmd(41, 0);
iva2k	0:886e4b3119ad	148	if(response == 0) {
iva2k	0:886e4b3119ad	149	break;
iva2k	0:886e4b3119ad	150	} else if(i > SD_COMMAND_TIMEOUT) {
iva2k	0:886e4b3119ad	151	fprintf(stderr, "Timeout waiting for card" CR);
iva2k	0:886e4b3119ad	152	return 1;
iva2k	0:886e4b3119ad	153	}
iva2k	0:886e4b3119ad	154	}
iva2k	0:886e4b3119ad	155
iva2k	0:886e4b3119ad	156	// printf("OK" CR);
iva2k	0:886e4b3119ad	157
iva2k	0:886e4b3119ad	158	_sectors = _sd_sectors();
iva2k	0:886e4b3119ad	159
iva2k	0:886e4b3119ad	160	// Set block length to 512 (CMD16)
iva2k	0:886e4b3119ad	161	if(_cmd(16, 512) != 0) {
iva2k	0:886e4b3119ad	162	fprintf(stderr, "Set block timeout" CR);
iva2k	0:886e4b3119ad	163	return 1;
iva2k	0:886e4b3119ad	164	}
iva2k	0:886e4b3119ad	165
iva2k	0:886e4b3119ad	166	_spi.frequency(1000000); // Set to 1MHz for data transfer
iva2k	0:886e4b3119ad	167	return 0;
iva2k	0:886e4b3119ad	168	}
iva2k	0:886e4b3119ad	169
iva2k	0:886e4b3119ad	170	int SDFileSystem::disk_write(const char *buffer, int block_number) {
iva2k	0:886e4b3119ad	171	// set write address for single block (CMD24)
iva2k	0:886e4b3119ad	172	if(_cmd(24, block_number * 512) != 0) {
iva2k	0:886e4b3119ad	173	return 1;
iva2k	0:886e4b3119ad	174	}
iva2k	0:886e4b3119ad	175
iva2k	0:886e4b3119ad	176	// send the data block
iva2k	0:886e4b3119ad	177	_write(buffer, 512);
iva2k	0:886e4b3119ad	178	return 0;
iva2k	0:886e4b3119ad	179	}
iva2k	0:886e4b3119ad	180
iva2k	0:886e4b3119ad	181	int SDFileSystem::disk_read(char *buffer, int block_number) {
iva2k	0:886e4b3119ad	182	// set read address for single block (CMD17)
iva2k	0:886e4b3119ad	183	if(_cmd(17, block_number * 512) != 0) {
iva2k	0:886e4b3119ad	184	return 1;
iva2k	0:886e4b3119ad	185	}
iva2k	0:886e4b3119ad	186
iva2k	0:886e4b3119ad	187	// receive the data
iva2k	0:886e4b3119ad	188	_read(buffer, 512);
iva2k	0:886e4b3119ad	189	return 0;
iva2k	0:886e4b3119ad	190	}
iva2k	0:886e4b3119ad	191
iva2k	0:886e4b3119ad	192	int SDFileSystem::disk_status() { return 0; }
iva2k	0:886e4b3119ad	193	int SDFileSystem::disk_sync() { return 0; }
iva2k	0:886e4b3119ad	194	int SDFileSystem::disk_sectors() { return _sectors; }
iva2k	0:886e4b3119ad	195
iva2k	0:886e4b3119ad	196	// PRIVATE FUNCTIONS
iva2k	0:886e4b3119ad	197
iva2k	0:886e4b3119ad	198	int SDFileSystem::_cmd(int cmd, int arg) {
iva2k	0:886e4b3119ad	199	_cs = 0;
iva2k	0:886e4b3119ad	200
iva2k	0:886e4b3119ad	201	// send a command
iva2k	0:886e4b3119ad	202	_spi.write(0x40 \| cmd);
iva2k	0:886e4b3119ad	203	_spi.write(arg >> 24);
iva2k	0:886e4b3119ad	204	_spi.write(arg >> 16);
iva2k	0:886e4b3119ad	205	_spi.write(arg >> 8);
iva2k	0:886e4b3119ad	206	_spi.write(arg >> 0);
iva2k	0:886e4b3119ad	207	_spi.write(0x95);
iva2k	0:886e4b3119ad	208
iva2k	0:886e4b3119ad	209	// wait for the repsonse (response[7] == 0)
iva2k	0:886e4b3119ad	210	for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
iva2k	0:886e4b3119ad	211	int response = _spi.write(0xFF);
iva2k	0:886e4b3119ad	212	if(!(response & 0x80)) {
iva2k	0:886e4b3119ad	213	_cs = 1;
iva2k	0:886e4b3119ad	214	_spi.write(0xFF);
iva2k	0:886e4b3119ad	215	return response;
iva2k	0:886e4b3119ad	216	}
iva2k	0:886e4b3119ad	217	}
iva2k	0:886e4b3119ad	218	_cs = 1;
iva2k	0:886e4b3119ad	219	_spi.write(0xFF);
iva2k	0:886e4b3119ad	220	return -1; // timeout
iva2k	0:886e4b3119ad	221	}
iva2k	0:886e4b3119ad	222
iva2k	0:886e4b3119ad	223	int SDFileSystem::_cmd8() {
iva2k	0:886e4b3119ad	224	_cs = 0;
iva2k	0:886e4b3119ad	225
iva2k	0:886e4b3119ad	226	// send a command
iva2k	0:886e4b3119ad	227	_spi.write(0x40 \| 8); // CMD8
iva2k	0:886e4b3119ad	228	_spi.write(0x00); // reserved
iva2k	0:886e4b3119ad	229	_spi.write(0x00); // reserved
iva2k	0:886e4b3119ad	230	_spi.write(0x01); // 3.3v
iva2k	0:886e4b3119ad	231	_spi.write(0xAA); // check pattern
iva2k	0:886e4b3119ad	232	_spi.write(0x87); // crc
iva2k	0:886e4b3119ad	233
iva2k	0:886e4b3119ad	234	// wait for the repsonse (response[7] == 0)
iva2k	0:886e4b3119ad	235	for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) {
iva2k	0:886e4b3119ad	236	char response[5];
iva2k	0:886e4b3119ad	237	response[0] = _spi.write(0xFF);
iva2k	0:886e4b3119ad	238	if(!(response[0] & 0x80)) {
iva2k	0:886e4b3119ad	239	for(int j=1; j<5; j++) {
iva2k	0:886e4b3119ad	240	response[i] = _spi.write(0xFF);
iva2k	0:886e4b3119ad	241	}
iva2k	0:886e4b3119ad	242	_cs = 1;
iva2k	0:886e4b3119ad	243	_spi.write(0xFF);
iva2k	0:886e4b3119ad	244	return response[0];
iva2k	0:886e4b3119ad	245	}
iva2k	0:886e4b3119ad	246	}
iva2k	0:886e4b3119ad	247	_cs = 1;
iva2k	0:886e4b3119ad	248	_spi.write(0xFF);
iva2k	0:886e4b3119ad	249	return -1; // timeout
iva2k	0:886e4b3119ad	250	}
iva2k	0:886e4b3119ad	251
iva2k	0:886e4b3119ad	252	int SDFileSystem::_read(char *buffer, int length) {
iva2k	0:886e4b3119ad	253	_cs = 0;
iva2k	0:886e4b3119ad	254
iva2k	0:886e4b3119ad	255	// read until start byte (0xFF)
iva2k	0:886e4b3119ad	256	while(_spi.write(0xFF) != 0xFE);
iva2k	0:886e4b3119ad	257
iva2k	0:886e4b3119ad	258	// read data
iva2k	0:886e4b3119ad	259	for(int i=0; i<length; i++) {
iva2k	0:886e4b3119ad	260	buffer[i] = _spi.write(0xFF);
iva2k	0:886e4b3119ad	261	}
iva2k	0:886e4b3119ad	262	_spi.write(0xFF); // checksum
iva2k	0:886e4b3119ad	263	_spi.write(0xFF);
iva2k	0:886e4b3119ad	264
iva2k	0:886e4b3119ad	265	_cs = 1;
iva2k	0:886e4b3119ad	266	_spi.write(0xFF);
iva2k	0:886e4b3119ad	267	return 0;
iva2k	0:886e4b3119ad	268	}
iva2k	0:886e4b3119ad	269
iva2k	0:886e4b3119ad	270	int SDFileSystem::_write(const char *buffer, int length) {
iva2k	0:886e4b3119ad	271	_cs = 0;
iva2k	0:886e4b3119ad	272
iva2k	0:886e4b3119ad	273	// indicate start of block
iva2k	0:886e4b3119ad	274	_spi.write(0xFE);
iva2k	0:886e4b3119ad	275
iva2k	0:886e4b3119ad	276	// write the data
iva2k	0:886e4b3119ad	277	for(int i=0; i<length; i++) {
iva2k	0:886e4b3119ad	278	_spi.write(buffer[i]);
iva2k	0:886e4b3119ad	279	}
iva2k	0:886e4b3119ad	280
iva2k	0:886e4b3119ad	281	// write the checksum
iva2k	0:886e4b3119ad	282	_spi.write(0xFF);
iva2k	0:886e4b3119ad	283	_spi.write(0xFF);
iva2k	0:886e4b3119ad	284
iva2k	0:886e4b3119ad	285	// check the repsonse token
iva2k	0:886e4b3119ad	286	if((_spi.write(0xFF) & 0x1F) != 0x05) {
iva2k	0:886e4b3119ad	287	_cs = 1;
iva2k	0:886e4b3119ad	288	_spi.write(0xFF);
iva2k	0:886e4b3119ad	289	return 1;
iva2k	0:886e4b3119ad	290	}
iva2k	0:886e4b3119ad	291
iva2k	0:886e4b3119ad	292	// wait for write to finish
iva2k	0:886e4b3119ad	293	while(_spi.write(0xFF) == 0);
iva2k	0:886e4b3119ad	294
iva2k	0:886e4b3119ad	295	_cs = 1;
iva2k	0:886e4b3119ad	296	_spi.write(0xFF);
iva2k	0:886e4b3119ad	297	return 0;
iva2k	0:886e4b3119ad	298	}
iva2k	0:886e4b3119ad	299
iva2k	0:886e4b3119ad	300	static int ext_bits(char *data, int msb, int lsb) {
iva2k	0:886e4b3119ad	301	int bits = 0;
iva2k	0:886e4b3119ad	302	int size = 1 + msb - lsb;
iva2k	0:886e4b3119ad	303	for(int i=0; i<size; i++) {
iva2k	0:886e4b3119ad	304	int position = lsb + i;
iva2k	0:886e4b3119ad	305	int byte = 15 - (position >> 3);
iva2k	0:886e4b3119ad	306	int bit = position & 0x7;
iva2k	0:886e4b3119ad	307	int value = (data[byte] >> bit) & 1;
iva2k	0:886e4b3119ad	308	bits \|= value << i;
iva2k	0:886e4b3119ad	309	}
iva2k	0:886e4b3119ad	310	return bits;
iva2k	0:886e4b3119ad	311	}
iva2k	0:886e4b3119ad	312
iva2k	0:886e4b3119ad	313	int SDFileSystem::_sd_sectors() {
iva2k	0:886e4b3119ad	314
iva2k	0:886e4b3119ad	315	// CMD9, Response R2 (R1 byte + 16-byte block read)
iva2k	0:886e4b3119ad	316	if(_cmd(9, 0) != 0) {
iva2k	0:886e4b3119ad	317	fprintf(stderr, "Didn't get a response from the disk" CR);
iva2k	0:886e4b3119ad	318	return 0;
iva2k	0:886e4b3119ad	319	}
iva2k	0:886e4b3119ad	320
iva2k	0:886e4b3119ad	321	char csd[16];
iva2k	0:886e4b3119ad	322	if(_read(csd, 16) != 0) {
iva2k	0:886e4b3119ad	323	fprintf(stderr, "Couldn't read csd response from disk" CR);
iva2k	0:886e4b3119ad	324	return 0;
iva2k	0:886e4b3119ad	325	}
iva2k	0:886e4b3119ad	326
iva2k	0:886e4b3119ad	327	// csd_structure : csd[127:126]
iva2k	0:886e4b3119ad	328	// c_size : csd[73:62]
iva2k	0:886e4b3119ad	329	// c_size_mult : csd[49:47]
iva2k	0:886e4b3119ad	330	// read_bl_len : csd[83:80]
iva2k	0:886e4b3119ad	331
iva2k	0:886e4b3119ad	332	int csd_structure = ext_bits(csd, 127, 126);
iva2k	0:886e4b3119ad	333	int c_size = ext_bits(csd, 73, 62);
iva2k	0:886e4b3119ad	334	int c_size_mult = ext_bits(csd, 49, 47);
iva2k	0:886e4b3119ad	335	int read_bl_len = ext_bits(csd, 83, 80);
iva2k	0:886e4b3119ad	336
iva2k	0:886e4b3119ad	337	if(csd_structure != 0) {
iva2k	0:886e4b3119ad	338	fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures" CR);
iva2k	0:886e4b3119ad	339	// Non-zero is SDHC.
iva2k	0:886e4b3119ad	340	return 0;
iva2k	0:886e4b3119ad	341	}
iva2k	0:886e4b3119ad	342
iva2k	0:886e4b3119ad	343	int blocks = (c_size + 1) * (1 << (c_size_mult + 2));
iva2k	0:886e4b3119ad	344	int block_size = 1 << read_bl_len;
iva2k	0:886e4b3119ad	345
iva2k	0:886e4b3119ad	346	if (block_size != 512 && block_size != 1024) {
iva2k	0:886e4b3119ad	347	fprintf(stderr, "This disk tastes funny! %d byte block. I only like 512 or 1024 -byte blocks" CR, block_size);
iva2k	0:886e4b3119ad	348	return 0;
iva2k	0:886e4b3119ad	349	}
iva2k	0:886e4b3119ad	350
iva2k	0:886e4b3119ad	351	return blocks;
iva2k	0:886e4b3119ad	352	}

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	03 Jan 2010
Imports:	79
Forks:	0
Commits:	3
Dependents:	0
Dependencies:	1
Followers:	5

SDFileSystem.cpp@2:360fda42fefd, 2010-01-12 (annotated)

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