Diff: main.cpp

Revision:

0:d4197e4552ea

Child:

1:1843a53b51a8

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat Jun 06 09:49:36 2015 +0000
@@ -0,0 +1,191 @@
+#include "mbed.h"
+#include "mbed_debug.h"
+
+#define SD_COMMAND_TIMEOUT 5000
+
+#define SD_DBG             0
+
+#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)
+
+int initialise_card();
+int initialise_card_v1();
+int initialise_card_v2();
+int cmd(int, int);
+int cmd58();
+int cmd8();
+
+int cdv;
+
+#define SDCARD_FAIL 0
+#define SDCARD_V1   1
+#define SDCARD_V2   2
+#define SDCARD_V2HC 3
+
+
+
+SPI spi(PTD6, PTD7, PTD5); // mosi, miso, sclk
+DigitalOut cs(PTD2);
+
+
+
+int main()
+{
+    while(1)
+    { initialise_card();
+      int result= initialise_card();
+      printf("%d\n",result);
+    }
+}
+
+
+
+
+int 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) {
+        debug("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 {
+        debug("Not in idle state after sending CMD8 (not an SD card?)\n");
+        return SDCARD_FAIL;
+    }
+}
+
+int initialise_card_v1() {
+    for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
+        cmd(55, 0);
+        if (cmd(41, 0) == 0) {
+            cdv = 512;
+            debug_if(SD_DBG, "\n\rInit: SEDCARD_V1\n\r");
+            return SDCARD_V1;
+        }
+    }
+    
+    debug("Timeout waiting for v1.x card\n");
+    return SDCARD_FAIL;
+}
+
+
+int initialise_card_v2() {
+    for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
+        wait_ms(50);
+        cmd58();
+        cmd(55, 0);
+        if (cmd(41, 0x40000000) == 0) {
+            cmd58();
+            debug_if(SD_DBG, "\n\rInit: SDCARD_V2\n\r");
+            cdv = 1;
+            return SDCARD_V2;
+        }
+    }
+    
+    debug("Timeout waiting for v2.x card\n");
+    return SDCARD_FAIL;
+}
+
+int 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 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;
+            cs = 1;
+            spi.write(0xFF);
+            return response;
+        }
+    }
+    cs = 1;
+    spi.write(0xFF);
+    return -1; // timeout
+}
+
+
+int 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
+}
\ No newline at end of file