Diff: SST25VF.cpp

Revision:

0:1633dfa4b768

Child:

1:533050c756e0

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SST25VF.cpp	Sun Jan 15 13:51:16 2012 +0000
@@ -0,0 +1,131 @@
+/* SST25VF - drive the Microchip SST25VF Serial Flash using SPI
+*/
+
+#include "mbed.h"
+#include "SST25VF.h"
+
+SST25VF::SST25VF(SPI& spi, PinName ncs) : _spi(spi), _ncs(ncs)  {
+
+    _spi.format(8,0);
+    _spi.frequency(SPI_FREQ);
+    deselect();
+    unlock();
+    chipErase();
+
+}
+
+void SST25VF::select() {
+    _ncs = 0;
+}
+
+void SST25VF::deselect() {
+    _ncs = 1;
+}
+
+void SST25VF::wren() {
+    select();
+    _spi.write(WREN);
+    deselect();
+    waitShort();
+}
+
+void SST25VF::wrdi() {
+    select();
+    _spi.write(WRDI);
+    deselect();
+}
+
+void SST25VF::chipErase() {
+    wren();
+    select();
+    _spi.write(CHIP_ERASE);
+    deselect();
+    waitErase();
+}
+
+void SST25VF::unlock() {
+    select();
+    _spi.write(WRITE_STATUS);
+    _spi.write(0);
+    deselect();
+    waitShort();
+}
+
+void SST25VF::writeStatus(char status) {
+    select();
+    _spi.write(WRITE_STATUS);
+    _spi.write(status);
+    deselect();
+    waitShort();
+}
+
+char SST25VF::readStatus() {
+    select();
+    _spi.write(READ_STATUS);
+    char result = (char) _spi.write(0);
+    deselect();
+    return result;
+}
+
+void SST25VF::prepareCommand(char command, long int address) {
+    select();
+    _spi.write(command);
+    _spi.write((address & 0xFFFFFF) >> 16);
+    _spi.write((address & 0xFFFF)>> 8);
+    _spi.write(address & 0xFF);
+}
+
+// write or read a single byte
+
+void SST25VF::write(long int address, char byte) {
+    wren();
+    prepareCommand(WRITE, address);
+    _spi.write(byte);
+    deselect();
+    waitShort();
+}
+
+char SST25VF::read(long int address) {
+    prepareCommand(READ, address);
+    int result = _spi.write(0);
+    deselect();
+    return (char) result;
+}
+
+// continuous write and read
+
+void SST25VF::write(long int address, char * buffer, int count) {
+    wren();
+    // write frist two bytes
+    for (int i = 0; i < count-1; i=i+2) {
+        if (i==0) {
+            prepareCommand(AAIWRITE, address);
+        } else {
+            select();
+            _spi.write(AAIWRITE);
+        }
+        _spi.write(buffer[i]);
+        _spi.write(buffer[i+1]);
+        deselect();
+        waitShort();
+    }
+    if ((count % 2) == 1) { // odd number of bytes       
+        select();
+        _spi.write(AAIWRITE);
+        _spi.write(buffer[count-1]);
+        _spi.write(0); // odd number of bytes, so write dummy byte to flash
+        deselect();
+        waitShort();
+    }
+    wrdi();
+    waitShort();
+}
+
+void SST25VF::read(long int address, char * buffer, int count) {
+    prepareCommand(READ, address);
+    // _spi.write(0); // dummy cycle, only necessary if READ is replaced by HSREAD
+    for (int i = 0; i < count; i++) {
+        buffer[i] = _spi.write(0);
+    }
+    deselect();
+}
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