Revision 0:6c621d41bf07, committed 2010-12-08

Comitter:

ashwin_athani

Date:

Wed Dec 08 06:21:06 2010 +0000

Commit message:

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FATFileSystem.lib	Wed Dec 08 06:21:06 2010 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_unsupported/code/fatfilesystem/
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDFileSystem.cpp	Wed Dec 08 06:21:06 2010 +0000
@@ -0,0 +1,300 @@
+/* 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() {
+
+    _spi.frequency(100000); // Set to 100kHz for initialisation
+    
+    // Initialise the card by clocking it with cs = 1
+    _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;
+            _spi.write(0xFF);
+            return response;
+        }
+    }
+    _cs = 1;
+    _spi.write(0xFF);
+    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;    
+    _spi.write(0xFF);
+    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;
+        _spi.write(0xFF);        
+        return 1;
+    }
+
+    // wait for write to finish
+    while(_spi.write(0xFF) == 0);
+
+    _cs = 1; 
+    _spi.write(0xFF);
+    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;
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDFileSystem.h	Wed Dec 08 06:21:06 2010 +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

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Dec 08 06:21:06 2010 +0000
@@ -0,0 +1,189 @@
+#include "mbed.h"
+#include "SDFileSystem.h"
+
+AnalogOut DACout(p18);
+DigitalOut led1(LED1);
+DigitalOut led2(LED2);
+DigitalOut led3(LED3);
+DigitalOut led4(p8);
+DigitalOut digout(LED4);
+Ticker tick;
+//SDFileSystem sd(p11, p12, p13, p14, "sd");
+SDFileSystem sd(p5, p6, p7, p8, "sd"); // NGX mbed base board
+
+#define SAMPLE_FREQ 40000
+#define BUF_SIZE (SAMPLE_FREQ/10)
+#define SLICE_BUF_SIZE 1
+
+void dac_out(void);
+void play_wave(char *);
+void cleanup(char *);
+void fill_adc_buf(short *, unsigned);
+void swapword(unsigned *);
+
+// a FIFO for the DAC
+short DAC_fifo[256];
+short DAC_wptr;
+short DAC_rptr;
+short DAC_on;
+
+typedef struct uFMT_STRUCT {
+  short comp_code;
+  short num_channels;
+  unsigned sample_rate;
+  unsigned avg_Bps;
+  short block_align;
+  short sig_bps;
+} FMT_STRUCT;
+
+
+int main() {
+  led1=0; wait(.5); led1=1; wait(.5); led1=0;
+  printf("Hello, world!\n");
+  play_wave("/sd/forest.wav");
+  printf("Back from forest\n");
+  printf("Goodbye, world!\n");
+  led1=1; wait(.5); led1=0; wait(.5); led1=1;
+}
+  
+void play_wave(char *wavname)
+{
+        unsigned chunk_id,chunk_size,channel;
+//        unsigned *data_wptr,data,samp_int,i;
+        unsigned data,samp_int,i;
+        short dac_data;
+        char *slice_buf;
+        short *data_sptr;
+//        char *data_bptr;
+        FMT_STRUCT wav_format;
+        FILE *wavfile;
+        long slice,num_slices;
+  DAC_wptr=0;
+  DAC_rptr=0;
+  for (i=0;i<256;i+=2) {
+    DAC_fifo[i]=0;
+    DAC_fifo[i+1]=3000;
+  }
+  DAC_wptr=4;
+  DAC_on=0;
+
+  led1=led2=led3=led4=0;
+  
+  printf("Playing wave file '%s'\n",wavname);
+
+  wavfile=fopen(wavname,"rb");
+  if (!wavfile) {
+    printf("Unable to open wav file '%s'\n",wavname);
+    exit(1);
+  }
+
+  fread(&chunk_id,4,1,wavfile);
+  fread(&chunk_size,4,1,wavfile);
+  while (!feof(wavfile)) {
+    printf("Read chunk ID 0x%x, size 0x%x\n",chunk_id,chunk_size);
+    switch (chunk_id) {
+      case 0x46464952:
+        fread(&data,4,1,wavfile);
+        printf("RIFF chunk\n");
+        printf("  chunk size %d (0x%x)\n",chunk_size,chunk_size);
+        printf("  RIFF type 0x%x\n",data);
+        break;
+      case 0x20746d66:
+        fread(&wav_format,sizeof(wav_format),1,wavfile);
+        printf("FORMAT chunk\n");
+        printf("  chunk size %d (0x%x)\n",chunk_size,chunk_size);
+        printf("  compression code %d\n",wav_format.comp_code);
+        printf("  %d channels\n",wav_format.num_channels);
+        printf("  %d samples/sec\n",wav_format.sample_rate);
+        printf("  %d bytes/sec\n",wav_format.avg_Bps);
+        printf("  block align %d\n",wav_format.block_align);
+        printf("  %d bits per sample\n",wav_format.sig_bps);
+        if (chunk_size > sizeof(wav_format))
+          fseek(wavfile,chunk_size-sizeof(wav_format),SEEK_CUR);
+// create a slice buffer large enough to hold multiple slices
+        slice_buf=(char *)malloc(wav_format.block_align*SLICE_BUF_SIZE);
+        if (!slice_buf) {
+          printf("Unable to malloc slice buffer");
+          exit(1);
+        }
+        break;
+      case 0x61746164:
+        slice_buf=(char *)malloc(wav_format.block_align*SLICE_BUF_SIZE);
+        if (!slice_buf) {
+          printf("Unable to malloc slice buffer");
+          exit(1);
+        }        num_slices=chunk_size/wav_format.block_align;
+        printf("DATA chunk\n");
+        printf("  chunk size %d (0x%x)\n",chunk_size,chunk_size);
+        printf("  %d slices\n",num_slices);
+        printf("  Ideal sample interval=%d\n",(unsigned)(1000000.0/wav_format.sample_rate));
+        samp_int=1000000/(wav_format.sample_rate);
+        printf("  programmed interrupt tick interval=%d\n",samp_int);
+
+// starting up ticker to write samples out -- no printfs until tick.detach is called
+        tick.attach_us(&dac_out, samp_int); 
+        DAC_on=1; 
+        led2=1;
+        for (slice=0;slice<num_slices;slice+=SLICE_BUF_SIZE) {
+          fread(slice_buf,wav_format.block_align*SLICE_BUF_SIZE,1,wavfile);
+          if (feof(wavfile)) {
+            printf("Oops -- not enough slices in the wave file\n");
+            exit(1);
+          }
+          data_sptr=(short *)slice_buf;
+          for (i=0;i<SLICE_BUF_SIZE;i++) {
+            dac_data=0;
+
+// for a stereo wave file average the two channels.
+            for (channel=0;channel<wav_format.num_channels;channel++) {
+              switch (wav_format.sig_bps) {
+                case 16:
+                  dac_data+=(  ((int)(*data_sptr++)) +32768)>>5;
+                  break;
+              }
+            }
+            dac_data>>=1;
+            DAC_fifo[DAC_wptr]=dac_data;
+            DAC_wptr=(DAC_wptr+1) & 0xff;
+            while (DAC_wptr==DAC_rptr) {
+              led1=1;
+            }
+            led1=0;
+          }
+        }
+        DAC_on=0;
+        led2=0;
+        tick.detach();
+        printf("Ticker detached\n");
+        led3=1;
+        free(slice_buf);
+        break;
+      case 0x5453494c:
+        printf("INFO chunk, size %d\n",chunk_size);
+        fseek(wavfile,chunk_size,SEEK_CUR);
+        break;
+      default:
+        printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size);
+        data=fseek(wavfile,chunk_size,SEEK_CUR);
+        break;
+    }
+    fread(&chunk_id,4,1,wavfile);
+    fread(&chunk_size,4,1,wavfile);
+  }
+  printf("Done with wave file\n");
+  fclose(wavfile);
+  led1=0;
+}
+
+
+void dac_out()
+{
+  if (DAC_on) {
+    digout=1;
+    DACout.write_u16(DAC_fifo[DAC_rptr]);
+    DAC_rptr=(DAC_rptr+1) & 0xff;
+    digout=0;
+  }
+}
+
+    

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Wed Dec 08 06:21:06 2010 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/49a220cc26e0