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Library to drive the Microchip 23K256 SRAM over SPI.
Diff: Ser23K256.cpp
- Revision:
- 3:d2314b1ac797
- Parent:
- 2:f96c3c85aa3b
--- a/Ser23K256.cpp Sun Aug 15 13:06:52 2010 +0000 +++ b/Ser23K256.cpp Sun Aug 15 14:28:05 2010 +0000 @@ -1,91 +1,84 @@ -// 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); +/* 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" +#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