FRAMSPI.h

00001 /* FRAM_SPI - Ramtron FRAM FM24VXX series driver
00002 * Copyright (c) 2012 Oleg Evsegneev
00003 * Released under the MIT License: http://mbed.org/license/mit
00004 *
00005 * Datasheet http://www.ramtron.com/files/datasheets/FM25V02_ds.pdf
00006 */
00007 
00008 #ifndef  FRAMSPI_
00009 #define  FRAMSPI_
00010 
00011 #include "mbed.h"
00012 
00013 // commands
00014 #define READ            0x03
00015 #define WRITE           0x02
00016 #define READ_STATUS     0x05 // RDSR
00017 #define WRITE_ENABLED   0x06 // WREN
00018 #define WRITE_STATUS    0x01 // WRSR
00019 #define READ_ID         0x9F // RDID
00020 #define READ_SN         0xC3 // RSN
00021 
00022 /** An interface for the Ramtron FM25VXX FRAM over SPI
00023 *
00024 * 
00025 *
00026 * @code
00027 * #include "mbed.h"
00028 * #include "FRAMSPI.h"
00029 * 
00030 * SPI spi(p5,p6,p7);
00031 * FRAMSPI fram(spi,p8);
00032 * Serial pc(USBTX, USBRX);
00033 * 
00034 * int main() {
00035 *     char wdata[] = "Hello world!";
00036 *     char rdata[14];
00037 * 
00038 *     fram.write(0, wdata, 13); // 12 symbols + zero terminator
00039 *     fram.read(0, rdata, 13);
00040 * 
00041 *     pc.printf("data: %s", rdata);
00042 * }
00043 * @endcode
00044 * connections:
00045 * chip pin 1 to any GPIO. Chip select (!S)
00046 * chip pin 2 SO to MISO. Write (!W)
00047 * chip pin 3 to Vout or N/C
00048 * chip pin 4 to Gnd
00049 * chip pin 5 SI to MOSI
00050 * chip pin 6 SCK to sck 
00051 * chip pin 7 to Vout. !Hold
00052 * chip pin 8 to Vout
00053 */
00054 
00055 class FRAMSPI {
00056 
00057 public:
00058     /** Create an interface
00059     *
00060     * @param spi    An SPI object
00061     * @param ncs    Chip select pin
00062     */
00063     FRAMSPI(SPI& spi, PinName ncs);
00064 
00065     /** read chip 8 byte device ID
00066     */
00067     void readID(char *buff);
00068 
00069     /** read chip 2 byte serial number
00070     */
00071     void readSN(char *buff);
00072 
00073     /** read a byte from FRAM
00074     * @param addr    The address to read from
00075     * @return the byte at that address
00076     */
00077     char read(int addr);
00078 
00079     /** read multiple bytes from FRAM into a buffer
00080     * @param addr    The FRAM address to read from
00081     * @param buff     The buffer to read into (must be big enough!)
00082     * @param cnt      The number of bytes to read
00083     */
00084     void read(int addr, char *buff, int cnt);
00085 
00086     /** write a byte to FRAM
00087     * @param addr    The address SFRAM to write to
00088     * @param data       The byte to write there
00089     */
00090     void write(int addr, char data);
00091 
00092     /** write multiple bytes to FRAM from a buffer
00093     * @param addr    The FRAM address write to
00094     * @param buff     The buffer to write from
00095     * @param cnt      The number of bytes to write
00096     */
00097     void write(int addr, char *buff, int cnt);
00098 
00099 private:
00100     SPI& _spi;
00101     DigitalOut _ncs;
00102     void prepareCommand(char cmd, int addr);
00103     void select();
00104     void deselect();
00105 };
00106 
00107 #endif