Revision 2:f96c3c85aa3b, committed 2010-08-15

Comitter:

romilly

Date:

Sun Aug 15 13:06:52 2010 +0000

Parent:

1:28eb43851e6e

Child:

3:d2314b1ac797

Commit message:

created a library.

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Ser23K256.cpp	Sun Aug 15 13:06:52 2010 +0000
@@ -0,0 +1,91 @@
+// Ser23K256 - drive the Microchip 23K256 SRAM using SPI
+// Copyright (c) 2010 Romilly Cocking
+// Released under the MIT License: http://mbed.org/license/mit
+
+// 23K256 data sheet at http://ww1.microchip.com/downloads/en/DeviceDoc/22100B.pdf
+
+// Page-mode commands have not been implemented; I have found no need for them yet.
+
+// Assumes spi mode is default (8,0).
+
+// You can clock the 23K256 at up to 20MHz, so it supports the mbed's maximum SPI frequency of 12MHz.
+
+#include "mbed.h"
+#include "Ser23K256.h"
+
+Ser23K256::Ser23K256(SPI& spi, PinName ncs) : _spi(spi), _ncs(ncs)  {
+    deselect();
+}
+
+void Ser23K256::select() {
+    _ncs = 0;
+}
+
+void Ser23K256::deselect() {
+    _ncs = 1;
+}
+
+void Ser23K256::writeStatus(char status) {
+    select();
+    _spi.write(WRITE_STATUS);
+    _spi.write(status);
+    deselect();
+}
+
+char Ser23K256::readStatus() {
+    select();
+    _spi.write(READ_STATUS);
+    char result = (char) _spi.write(0);
+    deselect();
+    return result;
+}
+
+void Ser23K256::prepareCommand(char command, int address) {
+    select();
+    _spi.write(command);
+    _spi.write(address >> 8);
+    _spi.write(address & 0xFF);
+}
+
+// write or read a single byte
+
+void Ser23K256::write(int address, char byte) {
+    prepareCommand(WRITE, address);
+    _spi.write(byte);
+    deselect();
+}
+
+char Ser23K256::read(int address) {
+    prepareCommand(READ, address);
+    int result = _spi.write(0);
+    deselect();
+    return (char) result;
+}
+
+// buffered write and read
+
+/*
+* the single-byte read and write assume the 23K256 is in its default byte-mode
+* so sequential-model commands must switch the chip into sequential mode
+* at the start and return it to byte mode at the end.
+*/
+
+void Ser23K256::write(int address, char * buffer, int count) {
+    writeStatus(SEQUENTIAL_MODE);
+    prepareCommand(WRITE, address);
+    for (int i = 0; i < count; i++) {
+        _spi.write(buffer[i]);
+    }
+    deselect();
+    writeStatus(BYTE_MODE);
+}
+
+void Ser23K256::read(int address, char * buffer, int count) {
+    writeStatus(SEQUENTIAL_MODE);
+    prepareCommand(READ, address);
+    for (int i = 0; i < count; i++) {
+        buffer[i] = _spi.write(0);
+    }
+    deselect();
+    writeStatus(BYTE_MODE);
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Ser23K256.h	Sun Aug 15 13:06:52 2010 +0000
@@ -0,0 +1,37 @@
+// Ser23K256 - drive the Microchip 23K256 SRAM using SPI
+// Copyright (c) 2010 Romilly Cocking
+// Released under the MIT License: http://mbed.org/license/mit
+
+#include "mbed.h"
+
+#ifndef  SER23K256_H
+#define  SER23K256_H
+
+// mode codes for 23K256
+#define BYTE_MODE       0x00
+#define SEQUENTIAL_MODE 0x40
+
+// command codes for 23K256
+#define READ            0x03
+#define WRITE           0x02
+#define READ_STATUS     0x05 // called RDSR in datasheet
+#define WRITE_STATUS    0x01 // called WRSR in datasheet
+
+class Ser23K256 {
+public:
+    Ser23K256(SPI& spi, PinName ncs);
+    char read(int address);
+    void read(int address, char * buffer, int count);
+    void write(int address, char byte);
+    void write(int address, char * buffer, int count);
+private:
+    SPI& _spi;
+    DigitalOut _ncs;
+    char readStatus();
+    void writeStatus(char status);
+    void prepareCommand(char command, int address);
+    void select();
+    void deselect();
+};
+
+#endif

--- a/main.cpp	Sun Aug 15 10:10:05 2010 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,114 +0,0 @@
-#include "mbed.h"
-
-DigitalOut ncs(p14);
-SPI spi(p5,p6,p7);
-
-// 23K256 data sheet at http://ww1.microchip.com/downloads/en/DeviceDoc/22100B.pdf
-
-// Page-mode commands have not been implemented; I have found no need for them yet.
-
-// Assumes spi mode is default (8,0).
-
-// The 23K256 supports the mbed's maximum spi frequency of 12MHz.
-
-// mode codes for 23K256
-#define BYTE_MODE       0x00
-#define SEQUENTIAL_MODE 0x40
-
-// command codes for 23K256
-#define READ            0x03
-#define WRITE           0x02
-#define READ_STATUS     0x05 // called RDSR in datasheet
-#define WRITE_STATUS    0x01 // called WRSR in datasheet
-
-inline void on() {
-    ncs = 0;
-}
-
-inline void off() {
-    ncs = 1;
-}
-
-void writeStatus(char status) {
-    on();
-    spi.write(WRITE_STATUS);
-    spi.write(status);
-    off();
-}
-
-int readStatus() {
-    on();
-    spi.write(READ_STATUS);
-    int result = spi.write(0);
-    off();
-    return result;
-}
-
-inline void prepareCommand(char command, int address) {
-    on();
-    spi.write(command);
-    spi.write(address >> 8);
-    spi.write(address & 0xFF);
-}
-
-// write or read a single byte
-
-void write(int address, char byte) {
-    prepareCommand(WRITE, address);
-    spi.write(byte);
-    off();
-}
-
-char read(int address) {
-    prepareCommand(READ, address);
-    int result = spi.write(0);
-    off();
-    return (char) result;
-}
-
-// buffered write and read
-
-/*
-* the single-byte read and write assume the 23K256 is in its default byte-mode
-* so sequential-model commands must switch the chip into sequential mode
-* at the start and return it to byte mode at the end.
-*/
-
-void write(int address, char * buffer, int count) {
-    writeStatus(SEQUENTIAL_MODE);
-    prepareCommand(WRITE, address);
-    for (int i = 0; i < count; i++) {
-        spi.write(buffer[i]);
-    }
-    off();
-    writeStatus(BYTE_MODE);
-}
-
-void read(int address, char * buffer, int count) {
-    writeStatus(SEQUENTIAL_MODE);
-    prepareCommand(READ, address);
-    for (int i = 0; i < count; i++) {
-        buffer[i] = spi.write(0);
-    }
-    off();
-    writeStatus(BYTE_MODE);
-}
-
-int main() {
-    off();
-    printf("Status codes: 0 = byte mode (default), 0x40 = sequential mode. "); 
-    printf("Status is currently %i\r\n", readStatus());
-    char buff[50];
-    write(0, 'h');
-    write(1, 'i');
-    write(2, '!');
-    write(3, '\0');
-    for (int address = 0; address < 4; address++) {
-        buff[address] = read(address);
-    }
-    printf("mem = %s\r\n", buff);
-    write(0, "Hello world!",12);
-    read(0, buff, 12);
-    buff[12]='\0';
-    printf("now = %s\r\n", buff);
-}
\ No newline at end of file