最近在調LCD屏時，走了很多彎路，浪費了很多時間，寫文檔做個記錄。
RA8871沒有寫寄存器/寫資料切換腳，它使用的是指令類型；每次會傳送雙倍的資料，如寫資料0x22，則需要發送0x80 0x22；
#define SPI_WRITE_DATA 0x80
#define SPI_READ_DATA 0xC0
#define SPI_WRITE_CMD 0x00
#define SPI_READ_STATUS 0x40
下面是寫資料的：發資料【0x80 value】
void LCD_DataWrite(uint _ucRegValue)
{
SPI_CS0(); //此處是供應商提供的STM32的源碼，在LInux核心使用GPIO-->SPI時，可以不處理CS腳
SPI_ShiftByte(SPI_WRITE_DATA); //0x80
SPI_ShiftByte(_ucRegValue);
SPI_CS1();
}
讀資料的：發資料【0xC0 0x00】
uchar LCD_DataRead(void)
{
uint value=0;
SPI_CS0();
SPI_ShiftByte(SPI_READ_DATA);
value = SPI_ShiftByte(0x00);
SPI_CS1();
return value;
}
設定寄存器值【0x00 寄存器】
void LCD_CmdWrite(uchar _ucRegAddr)
{
SPI_CS0();
SPI_ShiftByte(SPI_WRITE_CMD); //0x00
SPI_ShiftByte(_ucRegAddr);
SPI_CS1();
}
擷取狀态【0x40 0x00】
uchar LCD_StatusRead(void)
{
uchar value=0;
SPI_CS0();
SPI_ShiftByte(SPI_READ_STATUS);
value = SPI_ShiftByte(0x00);
SPI_CS1();
return value;
}
對應MTK平台使用測試代碼：spidev_test.c
/*
* SPI testing utility (using spidev driver)
*
* Copyright (c) 2007 MontaVista Software, Inc.
* Copyright (c) 2007 Anton Vorontsov <[email protected]>
*
* 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.
*
* Cross-compile with cross-gcc -I/path/to/cross-kernel/include
*/
#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>
#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
static void pabort(const char *s)
{
perror(s);
abort();
}
static const char *device = "/dev/spidev1.0";
static uint8_t mode;
static uint8_t bits = 8;
static uint32_t speed = 500000;
static uint16_t delay = 100;
static void transfer1(int fd, uint8_t *tx, int len)
{
int ret;
uint8_t rx[4] = {0};
struct spi_ioc_transfer tr = {
.tx_buf = tx,
.rx_buf = &rx,
.len = len,
.speed_hz = speed,
.delay_usecs = delay,
.bits_per_word = bits,
};
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1)
pabort("can't send spi message");
if(tx[2] == 0xC0) {
printf("ReadData:");
}
for (ret = 0; ret < len; ret++) {
if (!(ret % 6))
puts("");
printf("%.2X ", rx[ret]);
}
puts("");
}
static void print_usage(const char *prog)
{
printf("Usage: %s [-DsbdlHOLC3]\n", prog);
puts(" -D --device device to use (default /dev/spidev1.1)\n"
" -s --speed max speed (Hz)\n"
" -d --delay delay (usec)\n"
" -b --bpw bits per word \n"
" -l --loop loopback\n"
" -H --cpha clock phase\n"
" -O --cpol clock polarity\n"
" -L --lsb least significant bit first\n"
" -C --cs-high chip select active high\n"
" -3 --3wire SI/SO signals shared\n");
exit(1);
}
static void parse_opts(int argc, char *argv[])
{
while (1) {
static const struct option lopts[] = {
{ "device", 1, 0, 'D' },
{ "speed", 1, 0, 's' },
{ "delay", 1, 0, 'd' },
{ "bpw", 1, 0, 'b' },
{ "loop", 0, 0, 'l' },
{ "cpha", 0, 0, 'H' },
{ "cpol", 0, 0, 'O' },
{ "lsb", 0, 0, 'L' },
{ "cs-high", 0, 0, 'C' },
{ "3wire", 0, 0, '3' },
{ "no-cs", 0, 0, 'N' },
{ "ready", 0, 0, 'R' },
{ NULL, 0, 0, 0 },
};
int c;
c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL);
if (c == -1)
break;
switch (c) {
case 'D':
device = optarg;
break;
case 's':
speed = atoi(optarg);
break;
case 'd':
delay = atoi(optarg);
break;
case 'b':
bits = atoi(optarg);
break;
case 'l':
mode |= SPI_LSB_FIRST;
break;
case 'C':
mode |= SPI_CS_HIGH;
break;
case '3':
mode |= SPI_3WIRE;
break;
case 'N':
mode |= SPI_NO_CS;
break;
case 'R':
mode |= SPI_READY;
break;
default:
print_usage(argv[0]);
break;
}
}
}
unsigned char to_value(char c)
{
if(c >= '0' && c <= '9') {
return (c - '0');
} else if (c >= 'a' && c <= 'f') {
return (c - 'a') + 10;
} else if (c >= 'A' && c <= 'F') {
return (c - 'A') + 10;
}
return 0;
}
unsigned char str_to_uchar(char *str)
{
unsigned char ch = 0;
if(strlen(str) != 2) {
return 0;
}
return (to_value(str[0])*16 + to_value(str[1]));
}
int main(int argc, char *argv[])
{
int ret = 0;
int fd;
parse_opts(argc, argv);
fd = open(device, O_RDWR);
if (fd < 0)
pabort("can't open device");
/*
* spi mode
*/
ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
if (ret == -1)
pabort("can't set spi mode");
ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
if (ret == -1)
pabort("can't get spi mode");
/*
* bits per word
*/
ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
if (ret == -1)
pabort("can't set bits per word");
ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
if (ret == -1)
pabort("can't get bits per word");
/*
* max speed hz
*/
ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
if (ret == -1)
pabort("can't set max speed hz");
ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
if (ret == -1)
pabort("can't get max speed hz");
uint8_t rx1[4] = {0};
rx1[0] = str_to_uchar(argv[1]);
rx1[1] = str_to_uchar(argv[2]);
rx1[2] = str_to_uchar(argv[3]);
rx1[3] = str_to_uchar(argv[4]);
transfer1(fd, rx1, 4);
close(fd);
return ret;
}
編譯出的可執行檔案，測試結果讀、寫對應寄存器和狀态：
以REG[86h為例，在開發時，由于各種原因，我以為ReadData會一直傳回00或者C0，故将此寄存器的初始值設定為了0x00， 使得初始化時，屏隻是閃了下就滅了。後來找了含寄存器說明的晶片datasheet，原因才明确，如下：
REG[86h]在的預設初始參數為0x22，在bit1為0【One-shot】時，bit0會自動變為0，bit0控制的是屏的亮滅；
讀取REG[86h]的初始值
下面的STM32中亮屏的源碼：
void Start_PWM0(void)
{
/*
PWM Timer 0 start/stop
Determine start/stop for Timer 0.
0 = Stop
1 = Start for Timer 0
*/
unsigned char temp;
LCD_CmdWrite(0x86);
temp = LCD_DataRead();
temp |= cSetD0; //#define cSetD0 0x01
LCD_DataWrite(temp);
}
運作後，再次讀寄存器0x86的值，結果如下：
通過上述方法，對移植STM32的源碼移植到MTK平台中存在的問題，就能從本質上分析原因了。