Itead SPI sample

Itead_spi_sample.c

/*
 * (C) Copyright 2014
 * okada.takahiro111@gmail.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * Sample to read/write "mbed Geta SPI PRAM 128Mbit" from Iteaduino A20.
 * reference URL:
 *    http://www.galileo-7.com/?pid=53257954
 *    http://mbed.org/users/okini3939/code/SPIRAM_NP8P128A13TSM60E/file/3a2094fa7c4c/main.cpp
 *
 *
 * PIN ASSIGNMENT
 *  [SRAM]    [ITEAD]
 *   GND  ---- GND
 *   40   ---- 3V3
 *   11   ---- 112 (SPI0 MOSI)
 *   12   ---- 113 (SPI0 MISO)
 *   13   ---- 110 (SPI SCK)
 *   14   ---- 109 (SPI CS)
 *   15   ---- HIGH (3V3)
 *   16   ---- HIGH (3V3)
 *
 */

#include <itead.h>
#include <string.h>

#define CMD_WREN    0x06    // Write enable
#define CMD_READ    0x03    // Read data bytes
#define CMD_PP_BA   0x22    // Page program (bit-alterable write)
#define CMD_RDID    0x9f

const int cs = 109;

int SPIWrite(int addr, char *buf, int len) {
	int i;
	digitalWrite(cs, LOW);
	SPItransfer(0, CMD_WREN);
	digitalWrite(cs, HIGH);
	delay(10);

	digitalWrite(cs, LOW);
	SPItransfer(0, CMD_PP_BA);
	SPItransfer(0, (addr >> 16) & 0xff);
	SPItransfer(0, (addr >> 8) & 0xff);
	SPItransfer(0, addr & 0xff);

	len = len - (addr & 0x3f);
	for (i = 0; i < len; i ++) {
		SPItransfer(0,buf[i]);
	}
	digitalWrite(cs, HIGH);
	return i;
}

int SPIRead(int addr, char *buf, int len) {
	int i;

	digitalWrite(cs, LOW);
	SPItransfer(0, CMD_READ);
	SPItransfer(0, (addr >> 16) & 0xff);
	SPItransfer(0, (addr >> 8) & 0xff);
	SPItransfer(0, addr & 0xff);

	for (i = 0; i < len; i ++) {
		buf[i] = SPItransfer(0, 0);
	}
	digitalWrite(cs, HIGH);
	return i;
}

int main(){
	int i;

	// initialize
	pinMode(cs, OUTPUT);
	digitalWrite(cs, HIGH);
	SPIbegin(0);
	delay(50);

	//test to write
	char buf[6];
	strcpy(buf, "abcdef");
	SPIWrite(0, buf, 6);

	//test to read
	delay(1000);
	memset(buf, 0, 6);

	SPIRead(0, buf, 6);
	for (i = 0; i < 6; i ++) {
		printf(" %02x", buf[i]);
	}
}