Revision 0:b545e012d041, committed 2009-11-25

Comitter:

DaveStyles

Date:

Wed Nov 25 22:37:12 2009 +0000

Commit message:

Changed in this revision

diff -r 000000000000 -r b545e012d041 FATFileSystem.lib
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FATFileSystem.lib	Wed Nov 25 22:37:12 2009 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_unsupported/code/fatfilesystem/
\ No newline at end of file

diff -r 000000000000 -r b545e012d041 SDFileSystem.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDFileSystem.cpp	Wed Nov 25 22:37:12 2009 +0000
@@ -0,0 +1,297 @@
+/* mbed Microcontroller Library - SDFileSystem
+ * Copyright (c) 2008-2009, sford
+ *
+ * Introduction
+ * ------------
+ * SD and MMC cards support a number of interfaces, but common to them all
+ * is one based on SPI. This is the one I'm implmenting because it means
+ * it is much more portable even though not so performant, and we already 
+ * have the mbed SPI Interface!
+ *
+ * The main reference I'm using is Chapter 7, "SPI Mode" of: 
+ *  http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
+ *
+ * SPI Startup
+ * -----------
+ * The SD card powers up in SD mode. The SPI interface mode is selected by
+ * asserting CS low and sending the reset command (CMD0). The card will 
+ * respond with a (R1) response.
+ *
+ * CMD8 is optionally sent to determine the voltage range supported, and 
+ * indirectly determine whether it is a version 1.x SD/non-SD card or 
+ * version 2.x. I'll just ignore this for now.
+ *
+ * ACMD41 is repeatedly issued to initialise the card, until "in idle"
+ * (bit 0) of the R1 response goes to '0', indicating it is initialised.
+ *
+ * You should also indicate whether the host supports High Capicity cards,
+ * and check whether the card is high capacity - i'll also ignore this
+ *
+ * SPI Protocol
+ * ------------
+ * The SD SPI protocol is based on transactions made up of 8-bit words, with
+ * the host starting every bus transaction by asserting the CS signal low. The
+ * card always responds to commands, data blocks and errors.
+ * 
+ * The protocol supports a CRC, but by default it is off (except for the 
+ * first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
+ * I'll leave the CRC off I think! 
+ * 
+ * Standard capacity cards have variable data block sizes, whereas High 
+ * Capacity cards fix the size of data block to 512 bytes. I'll therefore
+ * just always use the Standard Capacity cards with a block size of 512 bytes.
+ * This is set with CMD16.
+ *
+ * You can read and write single blocks (CMD17, CMD25) or multiple blocks 
+ * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
+ * the card gets a read command, it responds with a response token, and then 
+ * a data token or an error.
+ * 
+ * SPI Command Format
+ * ------------------
+ * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
+ *
+ * +---------------+------------+------------+-----------+----------+--------------+
+ * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
+ * +---------------+------------+------------+-----------+----------+--------------+
+ *
+ * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
+ *
+ * All Application Specific commands shall be preceded with APP_CMD (CMD55).
+ *
+ * SPI Response Format
+ * -------------------
+ * The main response format (R1) is a status byte (normally zero). Key flags:
+ *  idle - 1 if the card is in an idle state/initialising 
+ *  cmd  - 1 if an illegal command code was detected
+ *
+ *    +-------------------------------------------------+
+ * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
+ *    +-------------------------------------------------+
+ *
+ * R1b is the same, except it is followed by a busy signal (zeros) until
+ * the first non-zero byte when it is ready again.
+ *
+ * Data Response Token
+ * -------------------
+ * Every data block written to the card is acknowledged by a byte 
+ * response token
+ *
+ * +----------------------+
+ * | xxx | 0 | status | 1 |
+ * +----------------------+
+ *              010 - OK!
+ *              101 - CRC Error
+ *              110 - Write Error
+ *
+ * Single Block Read and Write
+ * ---------------------------
+ *
+ * Block transfers have a byte header, followed by the data, followed
+ * by a 16-bit CRC. In our case, the data will always be 512 bytes.
+ *  
+ * +------+---------+---------+- -  - -+---------+-----------+----------+
+ * | 0xFE | data[0] | data[1] |        | data[n] | crc[15:8] | crc[7:0] | 
+ * +------+---------+---------+- -  - -+---------+-----------+----------+
+ */
+ 
+#include "SDFileSystem.h"
+
+#define SD_COMMAND_TIMEOUT 5000
+
+SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
+  FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
+      _cs = 1; 
+}
+
+int SDFileSystem::disk_initialize() {
+
+     fprintf(stderr,"Initialising\n");
+  
+
+    _spi.frequency(1000); // Set to 100kHz for initialisation
+    
+    // Initialise the card by clocking it a bit (cs = 1)
+    for(int i=0; i<16; i++) {   
+        _spi.write(0xFF);
+    }
+
+    // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
+    if(_cmd(0, 0) != 0x01) { 
+        fprintf(stderr, "Not in idle state\n");
+        return 1;
+    }
+    
+    // ACMD41 to give host capacity support (repeat until not busy)
+    // ACMD41 is application specific command, so we send APP_CMD (CMD55) beforehand
+    for(int i=0;; i++) {
+        _cmd(55, 0); 
+        int response = _cmd(41, 0);
+        if(response == 0) { 
+            break;
+        } else if(i > SD_COMMAND_TIMEOUT) {
+            fprintf(stderr, "Timeout waiting for card\n");
+            return 1;
+        }    
+    }
+
+    _sectors = _sd_sectors();
+
+    // Set block length to 512 (CMD16)
+    if(_cmd(16, 512) != 0) {
+        fprintf(stderr, "Set block timeout\n");
+        return 1;
+    }
+        
+    _spi.frequency(1000000); // Set to 1MHz for data transfer
+    return 0;
+}
+
+int SDFileSystem::disk_write(const char *buffer, int block_number) {
+    // set write address for single block (CMD24)
+    if(_cmd(24, block_number * 512) != 0) {
+        return 1;
+    }
+
+    // send the data block
+    _write(buffer, 512);    
+    return 0;    
+}
+
+int SDFileSystem::disk_read(char *buffer, int block_number) {        
+    // set read address for single block (CMD17)
+    if(_cmd(17, block_number * 512) != 0) {
+        return 1;
+    }
+    
+    // receive the data
+    _read(buffer, 512);
+    return 0;
+}
+
+int SDFileSystem::disk_status() { return 0; }
+int SDFileSystem::disk_sync() { return 0; }
+int SDFileSystem::disk_sectors() { return _sectors; }
+
+// PRIVATE FUNCTIONS
+
+int SDFileSystem::_cmd(int cmd, int arg) {
+    _cs = 0; 
+
+    // send a command
+    _spi.write(0x40 | cmd);
+    _spi.write(arg >> 24);
+    _spi.write(arg >> 16);
+    _spi.write(arg >> 8);
+    _spi.write(arg >> 0);
+    _spi.write(0x95);
+
+    // wait for the repsonse (response[7] == 0)
+    for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
+        int response = _spi.write(0xFF);
+        if(!(response & 0x80)) {
+            _cs = 1;
+            return response;
+        }
+    }
+    _cs = 1;
+    return -1; // timeout
+}
+
+int SDFileSystem::_read(char *buffer, int length) {
+    _cs = 0;
+
+    // read until start byte (0xFF)
+    while(_spi.write(0xFF) != 0xFE);
+
+    // read data
+    for(int i=0; i<length; i++) {
+        buffer[i] = _spi.write(0xFF);
+    }
+    _spi.write(0xFF); // checksum
+    _spi.write(0xFF);
+
+    _cs = 1;    
+    return 0;
+}
+
+int SDFileSystem::_write(const char *buffer, int length) {
+    _cs = 0;
+    
+    // indicate start of block
+    _spi.write(0xFE);
+    
+    // write the data
+    for(int i=0; i<length; i++) {
+        _spi.write(buffer[i]);
+    }
+    
+    // write the checksum
+    _spi.write(0xFF); 
+    _spi.write(0xFF);
+
+    // check the repsonse token
+    if((_spi.write(0xFF) & 0x1F) != 0x05) {
+        _cs = 1; 
+        return 1;
+    }
+
+    // wait for write to finish
+    while(_spi.write(0xFF) == 0);
+
+    _cs = 1; 
+    return 0;
+}
+
+static int ext_bits(char *data, int msb, int lsb) {
+    int bits = 0;
+    int size = 1 + msb - lsb; 
+    for(int i=0; i<size; i++) {
+        int position = lsb + i;
+        int byte = 15 - (position >> 3);
+        int bit = position & 0x7;
+        int value = (data[byte] >> bit) & 1;
+        bits |= value << i;
+    }
+    return bits;
+}
+
+int SDFileSystem::_sd_sectors() {
+
+    // CMD9, Response R2 (R1 byte + 16-byte block read)
+    if(_cmd(9, 0) != 0) {
+        fprintf(stderr, "Didn't get a response from the disk\n");
+        return 0;
+    }
+    
+    char csd[16];    
+    if(_read(csd, 16) != 0) {
+        fprintf(stderr, "Couldn't read csd response from disk\n");
+        return 0;
+    }
+
+    // csd_structure : csd[127:126]
+    // c_size        : csd[73:62]
+    // c_size_mult   : csd[49:47]
+    // read_bl_len   : csd[83:80] 
+
+    int csd_structure = ext_bits(csd, 127, 126);
+    int c_size = ext_bits(csd, 73, 62);
+    int c_size_mult = ext_bits(csd, 49, 47);
+    int read_bl_len = ext_bits(csd, 83, 80);
+    
+    if(csd_structure != 0) {
+        fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures");
+        return 0;
+    }
+                            
+    int blocks = (c_size + 1) * (1 << (c_size_mult + 2));
+    int block_size = 1 << read_bl_len;
+
+    if(block_size != 512) {
+        fprintf(stderr, "This disk tastes funny! I only like 512-byte blocks");
+        return 0;
+    }
+    
+    return blocks;
+}

diff -r 000000000000 -r b545e012d041 SDFileSystem.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDFileSystem.h	Wed Nov 25 22:37:12 2009 +0000
@@ -0,0 +1,56 @@
+/* mbed Microcontroller Library - SDFileSystem
+ * Copyright (c) 2008-2009, sford
+ */
+
+#ifndef SDFILESYSTEM_H
+#define SDFILESYSTEM_H
+
+#include "mbed.h"
+#include "FATFileSystem.h"
+
+/* Class: SDFileSystem
+ *  Access the filesystem on an SD Card using SPI
+ *
+ * Example:
+ * > SDFileSystem sd(p5, p6, p7, p12, "sd");
+ * > 
+ * > int main() {
+ * >     FILE *fp = fopen("/sd/myfile.txt", "w");
+ * >     fprintf(fp, "Hello World!\n");
+ * >     fclose(fp);
+ * > }
+ */
+class SDFileSystem : public FATFileSystem {
+public:
+
+	/* Constructor: SDFileSystem
+	 *  Create the File System for accessing an SD Card using SPI
+	 *
+	 * Variables:
+	 *  mosi - SPI mosi pin connected to SD Card
+	 *  miso - SPI miso pin conencted to SD Card
+	 *  sclk - SPI sclk pin connected to SD Card
+	 *  cs   - DigitalOut pin used as SD Card chip select
+   *  name - The name used to access the filesystem
+	 */
+	SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name);
+	virtual int disk_initialize();
+	virtual int disk_write(const char *buffer, int block_number);
+	virtual int disk_read(char *buffer, int block_number);	
+	virtual int disk_status();
+	virtual int disk_sync();
+	virtual int disk_sectors();
+
+protected:
+
+	int _cmd(int cmd, int arg);
+	int _read(char *buffer, int length);
+	int _write(const char *buffer, int length);
+	int _sd_sectors();
+	int _sectors;
+	
+	SPI _spi;
+	DigitalOut _cs;	 
+};
+
+#endif

diff -r 000000000000 -r b545e012d041 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Nov 25 22:37:12 2009 +0000
@@ -0,0 +1,50 @@
+#include "mbed.h"
+#include "SDFileSystem.h"
+//comment
+Serial pc(USBTX, USBRX); // tx, rx
+DigitalOut led1(LED1);
+SDFileSystem sd(p5, p6, p7, p8, "sd"); //i, o, clk, cs, const : on the card 3,7,5,2
+Ticker logger;
+
+void loggit() {
+    time_t seconds = time(NULL);
+    int mins = seconds/60;
+    int hours = seconds/3600;
+    int secs = seconds - (mins*60) - (hours * 3600);
+    pc.printf("FORMATTED ");
+    pc.printf("%04.4i:%02.2i:%02.2i \n\r", hours,mins,secs);
+
+    char  strh[4];
+    char  strm[2];
+    char  strs[2];
+
+    sprintf(strh, "%04.4i",hours);
+    sprintf(strm, "%02.2i",mins);
+    sprintf(strs, "%02.2i",secs);
+    FILE *lp = fopen("/sd/log.csv", "a");
+    pc.printf("Open");
+    fprintf(lp,strh);
+    fprintf(lp,":");
+    fprintf(lp,strm);
+    fprintf(lp,":");
+    fprintf(lp,strs);
+    fprintf(lp,",");
+    fprintf(lp,"12 \r");
+    fclose(lp);
+    pc.printf("Closed");
+}
+
+int main() {
+
+    set_time(1);
+
+    logger.attach(&loggit, 2.0);
+
+
+    while (1) {
+        led1 = !led1;
+        wait(1);
+
+    }
+
+}

diff -r 000000000000 -r b545e012d041 mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Wed Nov 25 22:37:12 2009 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/32af5db564d4