Revision 0:1633dfa4b768, committed 2012-01-15

Comitter:

emmibed

Date:

Sun Jan 15 13:51:16 2012 +0000

Commit message:

Changed in this revision

--- /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();
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SST25VF.h	Sun Jan 15 13:51:16 2012 +0000
@@ -0,0 +1,88 @@
+/** SST25VF - drive the Microchip SST25VF Serial Flash using SPI
+*
+* Assumes spi mode is default (8,0).
+*
+* You can clock the SST25VF at up to >20MHz, so it supports the mbed's maximum SPI frequency of 12MHz.
+*/
+
+#include "mbed.h"
+
+/* ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+*  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+*    Caution: Do not write to adresses where data != 0xFF
+*    Data in selected adress range MUST be 0xFF (See datasheet)
+*  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+*  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+*/
+
+#ifndef SST25VF_H
+#define SST25VF_H
+
+#define SPI_FREQ        12000000    // 12Mhz is mbed max (one eight of periph. clock)
+
+#define waitShort() wait_us(10)
+#define waitErase() wait_ms(50)
+
+// command codes for SST25VF
+#define WRITE_STATUS    0x01 // called WRSR in datasheet
+#define WRITE           0x02 // Byte-Program
+#define READ            0x03
+#define WRDI            0x04
+#define READ_STATUS     0x05 // called RDSR 
+#define WREN            0x06
+//#define HSREAD          0x0B // High-Speed-Read
+#define EWSR            0x50 // Enable-Write-Status-Register
+#define CHIP_ERASE      0x60
+#define AAIWRITE        0xAD // word based write
+
+class SST25VF {
+public:
+    /** Create an interface
+    *
+    *
+    * @param spi   An SPI object
+    * @param ncs   Not chip select pin - any free Digital pin will do
+    */
+    SST25VF(SPI& spi, PinName ncs);
+    /** read a byte from SRAM
+    * @param address    The address to read from
+    * @return the character at that address
+    */
+    char read(long int address);
+
+    /** read multiple bytes from SRAM into a buffer
+    * @param address    The SRAM address to read from
+    * @param buffer     The buffer to read into (must be big enough!)
+    * @param count      The number of bytes to read
+    */
+    void read(long int address, char * buffer, int count);
+    /** write a byte to SRAM
+    * @param address    The address SRAM to write to
+    * @param byte       The byte to write there
+    */
+    void write(long int address, char byte);
+    /** write multiple bytes to SRAM from a buffer
+    * @param address    The SRAM address write to
+    * @param buffer     The buffer to write from
+    * @param count      The number of bytes to write
+    */
+    void write(long int address, char * buffer, int count);
+
+
+    void chipErase();
+    char readStatus();
+
+private:
+    SPI& _spi;
+    DigitalOut _ncs;
+
+    void writeStatus(char status);
+    void prepareCommand(char command, long int address);
+    void select();
+    void deselect();
+    void wren();
+    void unlock();
+    void wrdi();
+};
+
+#endif

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Jan 15 13:51:16 2012 +0000
@@ -0,0 +1,35 @@
+#include "mbed.h"
+#include "SST25VF.h"
+
+#define w() wait_us(7)
+DigitalOut sr(p21);
+
+SPI spi(p5,p6,p7);
+
+SST25VF sram(spi,p21);
+
+int main() {
+
+    char buff[128];
+    
+    wait(0.2);
+
+   
+    sram.write((long) 0, 'o'); 
+    sram.write((long)1, 'n');
+    sram.write((long)2, 'e');
+    sram.write((long)3, '\0');
+    for (long int address = 0; address < 4; address++) {
+        buff[address] = sram.read(address);
+    }
+    printf("\noutput1 = %s\n", buff);
+    
+    sram.write((long)128, "Hello world!",12); // need separate address space here
+    
+    sram.read((long)128, buff, 12);
+    buff[12]='\0';
+    
+    printf("output2 = %s\n", buff);
+    
+
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Sun Jan 15 13:51:16 2012 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/9114680c05da