USBMSD SD card Hello World for Mbed platforms
Dependencies: mbed USBMSD_SD USBDevice
Diff: USBDevice/USBMSD/USB_SDcard.cpp
- Revision:
- 4:980e6470dcce
- Child:
- 6:126c4d980196
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/USBDevice/USBMSD/USB_SDcard.cpp Sat Nov 12 17:53:04 2011 +0000 @@ -0,0 +1,364 @@ +/* mbed USB_SDcard Library, for accessing SD cards + * Copyright (c) 2008-2010, sford + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "USB_SDcard.h" + +#define SD_COMMAND_TIMEOUT 5000 + +USB_SDcard::USB_SDcard(PinName mosi, PinName miso, PinName sclk, PinName cs): + _spi(mosi, miso, sclk), _cs(cs) { + _cs = 1; + init(); +} + +#define R1_IDLE_STATE (1 << 0) +#define R1_ERASE_RESET (1 << 1) +#define R1_ILLEGAL_COMMAND (1 << 2) +#define R1_COM_CRC_ERROR (1 << 3) +#define R1_ERASE_SEQUENCE_ERROR (1 << 4) +#define R1_ADDRESS_ERROR (1 << 5) +#define R1_PARAMETER_ERROR (1 << 6) + +// Types +// - v1.x Standard Capacity +// - v2.x Standard Capacity +// - v2.x High Capacity +// - Not recognised as an SD Card + +#define SDCARD_FAIL 0 +#define SDCARD_V1 1 +#define SDCARD_V2 2 +#define SDCARD_V2HC 3 + +int USB_SDcard::initialise_card() { + // Set to 100kHz for initialisation, and clock card with cs = 1 + _spi.frequency(100000); + _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) != R1_IDLE_STATE) { + fprintf(stderr, "No disk, or could not put SD card in to SPI idle state\n"); + return SDCARD_FAIL; + } + + // send CMD8 to determine whther it is ver 2.x + int r = _cmd8(); + if(r == R1_IDLE_STATE) { + return initialise_card_v2(); + } else if(r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) { + return initialise_card_v1(); + } else { + fprintf(stderr, "Not in idle state after sending CMD8 (not an SD card?)\n"); + return SDCARD_FAIL; + } +} + +int USB_SDcard::initialise_card_v1() { + for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { + _cmd(55, 0); + if(_cmd(41, 0) == 0) { + return SDCARD_V1; + } + } + + fprintf(stderr, "Timeout waiting for v1.x card\n"); + return SDCARD_FAIL; +} + +int USB_SDcard::initialise_card_v2() { + + for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { + _cmd(55, 0); + if(_cmd(41, 0) == 0) { + _cmd58(); + return SDCARD_V2; + } + } + + fprintf(stderr, "Timeout waiting for v2.x card\n"); + return SDCARD_FAIL; +} + +int USB_SDcard::init() { + + int i = initialise_card(); +// printf("init card = %d\n", i); +// printf("OK\n"); + + _sectors = _sd_sectors(); + + // Set block length to 512 (CMD16) + if(_cmd(16, 512) != 0) { + fprintf(stderr, "Set 512-byte block timed out\n"); + return 1; + } + + _spi.frequency(1000000); // Set to 1MHz for data transfer + return 0; +} + +int USB_SDcard::blockWrite(uint8_t * buffer, uint16_t block_number) { + // set write address for single block (CMD24) + if(_cmd(24, block_number * 512) != 0) { + return 1; + } + + // send the data block + _write((const char *)buffer, 512); + return 0; +} + +int USB_SDcard::blockRead(uint8_t * buffer, uint16_t block_number) { + // set read address for single block (CMD17) + if(_cmd(17, block_number * 512) != 0) { + return 1; + } + + // receive the data + _read((char *)buffer, 512); + return 0; +} + +int USB_SDcard::disk_status() { return 0; } +int USB_SDcard::disk_sync() { return 0; } +int USB_SDcard::disk_sectors() { return _sectors; } + +// PRIVATE FUNCTIONS + +int USB_SDcard::_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 USB_SDcard::_cmdx(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)) { + return response; + } + } + _cs = 1; + _spi.write(0xFF); + return -1; // timeout +} + + +int USB_SDcard::_cmd58() { + _cs = 0; + int arg = 0; + + // send a command + _spi.write(0x40 | 58); + _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)) { + int ocr = _spi.write(0xFF) << 24; + ocr |= _spi.write(0xFF) << 16; + ocr |= _spi.write(0xFF) << 8; + ocr |= _spi.write(0xFF) << 0; +// printf("OCR = 0x%08X\n", ocr); + _cs = 1; + _spi.write(0xFF); + return response; + } + } + _cs = 1; + _spi.write(0xFF); + return -1; // timeout +} + +int USB_SDcard::_cmd8() { + _cs = 0; + + // send a command + _spi.write(0x40 | 8); // CMD8 + _spi.write(0x00); // reserved + _spi.write(0x00); // reserved + _spi.write(0x01); // 3.3v + _spi.write(0xAA); // check pattern + _spi.write(0x87); // crc + + // wait for the repsonse (response[7] == 0) + for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) { + char response[5]; + response[0] = _spi.write(0xFF); + if(!(response[0] & 0x80)) { + for(int j=1; j<5; j++) { + response[i] = _spi.write(0xFF); + } + _cs = 1; + _spi.write(0xFF); + return response[0]; + } + } + _cs = 1; + _spi.write(0xFF); + return -1; // timeout +} + +int USB_SDcard::_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 USB_SDcard::_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 USB_SDcard::_sd_sectors() { + + // CMD9, Response R2 (R1 byte + 16-byte block read) + if(_cmdx(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] - the *maximum* read block length + + 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); + +// printf("CSD_STRUCT = %d\n", csd_structure); + + if(csd_structure != 0) { + fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n"); + return 0; + } + + // memory capacity = BLOCKNR * BLOCK_LEN + // where + // BLOCKNR = (C_SIZE+1) * MULT + // MULT = 2^(C_SIZE_MULT+2) (C_SIZE_MULT < 8) + // BLOCK_LEN = 2^READ_BL_LEN, (READ_BL_LEN < 12) + + int block_len = 1 << read_bl_len; + int mult = 1 << (c_size_mult + 2); + int blocknr = (c_size + 1) * mult; + int capacity = blocknr * block_len; + + int blocks = capacity / 512; + + return blocks; +}