pikeyd165 – Rev 1
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// spiram.h
//
// Header for a Little Library for accessing SPI RAM chips such as 23K256-I/P
// using bcm2835 library on Raspberry Pi
//
// Author: Mike McCauley
// Copyright (C) 2018 Mike McCauley
// This software is part of the bcm2835 library and is licensed under the same conditions
// $Id: $
#include <stdbool.h> // bool, true, false
#ifndef SPIRAM_h
#define SPIRAM_h
#define SPIRAM_HOLD_DISABLE 0x1
#define SPIRAM_MODE_BYTE (0x00 | SPIRAM_HOLD_DISABLE)
#define SPIRAM_MODE_PAGE (0x80 | SPIRAM_HOLD_DISABLE)
#define SPIRAM_MODE_STREAM (0x40 | SPIRAM_HOLD_DISABLE)
#define SPIRAM_MODE_INVALID 0xff
#define SPIRAM_OPCODE_READ_SR 0x05
#define SPIRAM_OPCODE_WRITE_SR 0x01
#define SPIRAM_OPCODE_READ 0x03
#define SPIRAM_OPCODE_WRITE 0x02
/* Size of a page in 23K256 */
#define SPIRAM_PAGE_SIZE 32
/*
* This library allows you to read and write data from an external SPI interfaced static ram (SRAM)
* such as 23K256 (256kbit = 32kByte)
* Byte and POage modes are supported.
* Valid addresses are from 0x0000 to 0x7fff
* Tested on RPI 3 Model B, Raspbian Jessie
*/
/*
* Initialise the spiram library, enables SPI with default divider of
* BCM2835_SPI_CLOCK_DIVIDER_65536 = 6.1035156kHz on RPI3.
* You can change the SPI speed after calling this by calling bcm2835_spi_setClockDivider()
* Returns true on success, false otherwise
*/
bool spiram_begin();
/*
* Stops using the RPI SPI functions and returns the GPIO pins to their default behaviour.
* Call this when you have finished using SPI forever, or at the end of your program
* Returns true on success, false otherwise
*/
bool spiram_end();
/*
* Read and returns the current value of the SRAM status register
*/
uint8_t spiram_read_sr();
/*
* Write a new value to the SRAM status register,
* usually one of SPIRAM_MODE_*
* You should never need to call this directly. Used internally.
* Returns true on success, false otherwise
*/
bool spiram_write_sr(uint8_t value);
/*
* Set the operating mode of the SRAM.
* Mode is one of SPIRAM_MODE_*. THis is done automatically
* by the spiram_write_* and spiram_read_* functions, so you would not normally
* need to call this directly.
* Returns true on success, false otherwise
*/
bool spiram_set_mode(uint8_t mode);
/*
* Reads a single byte from the given address and returns it.
*/
uint8_t spiram_read_byte(uint16_t address);
/*
* Writes a single byte to the given address.
* Returns true on success, false otherwise
*/
bool spiram_write_byte(uint16_t address, uint8_t value);
/*
* Reads a whole page of data (32 bytes) from the page starting at the given address.
* The read data is placed in buf. Be sure that there is enough rom there for it.
* Caution: if the starting address is not on a page boundary,
* it will wrap back to the beginning of the page.
* Returns true on success, false otherwise
*/
bool spiram_read_page(uint16_t address, uint8_t *buf);
/*
* Writes a whole page of data (32 bytes) to the page starting at the given address.
* Caution: if the starting address is not on a page boundary,
* it will wrap back to the beginning of the page.
* Returns true on success, false otherwise
*/
bool spiram_write_page(uint16_t address, uint8_t *buf);
#endif