backlight.c

//总体思路：
/* backlight + 0x80U---->在加crc校验
   拉高-->一段时间--->拉低--->一个周期后产生中断---->一个周期后产生中断（开始发送数据）
 */
#include <pwm.h>
#include <backlight.h>

static const unsigned char crc8_tab[] = {
	0x00, 0x07, 0x0E, 0x09, 0x1C, 0x1B, 0x12, 0x15,
	0x38, 0x3F, 0x36, 0x31, 0x24, 0x23, 0x2A, 0x2D,
	0x70, 0x77, 0x7E, 0x79, 0x6C, 0x6B, 0x62, 0x65,
	0x48, 0x4F, 0x46, 0x41, 0x54, 0x53, 0x5A, 0x5D,
	0xE0, 0xE7, 0xEE, 0xE9, 0xFC, 0xFB, 0xF2, 0xF5,
	0xD8, 0xDF, 0xD6, 0xD1, 0xC4, 0xC3, 0xCA, 0xCD,
	0x90, 0x97, 0x9E, 0x99, 0x8C, 0x8B, 0x82, 0x85,
	0xA8, 0xAF, 0xA6, 0xA1, 0xB4, 0xB3, 0xBA, 0xBD,
	0xC7, 0xC0, 0xC9, 0xCE, 0xDB, 0xDC, 0xD5, 0xD2,
	0xFF, 0xF8, 0xF1, 0xF6, 0xE3, 0xE4, 0xED, 0xEA,
	0xB7, 0xB0, 0xB9, 0xBE, 0xAB, 0xAC, 0xA5, 0xA2,
	0x8F, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9D, 0x9A,
	0x27, 0x20, 0x29, 0x2E, 0x3B, 0x3C, 0x35, 0x32,
	0x1F, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0D, 0x0A,
	0x57, 0x50, 0x59, 0x5E, 0x4B, 0x4C, 0x45, 0x42,
	0x6F, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7D, 0x7A,
	0x89, 0x8E, 0x87, 0x80, 0x95, 0x92, 0x9B, 0x9C,
	0xB1, 0xB6, 0xBF, 0xB8, 0xAD, 0xAA, 0xA3, 0xA4,
	0xF9, 0xFE, 0xF7, 0xF0, 0xE5, 0xE2, 0xEB, 0xEC,
	0xC1, 0xC6, 0xCF, 0xC8, 0xDD, 0xDA, 0xD3, 0xD4,
	0x69, 0x6E, 0x67, 0x60, 0x75, 0x72, 0x7B, 0x7C,
	0x51, 0x56, 0x5F, 0x58, 0x4D, 0x4A, 0x43, 0x44,
	0x19, 0x1E, 0x17, 0x10, 0x05, 0x02, 0x0B, 0x0C,
	0x21, 0x26, 0x2F, 0x28, 0x3D, 0x3A, 0x33, 0x34,
	0x4E, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5C, 0x5B,
	0x76, 0x71, 0x78, 0x7F, 0x6A, 0x6D, 0x64, 0x63,
	0x3E, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2C, 0x2B,
	0x06, 0x01, 0x08, 0x0F, 0x1A, 0x1D, 0x14, 0x13,
	0xAE, 0xA9, 0xA0, 0xA7, 0xB2, 0xB5, 0xBC, 0xBB,
	0x96, 0x91, 0x98, 0x9F, 0x8A, 0x8D, 0x84, 0x83,
	0xDE, 0xD9, 0xD0, 0xD7, 0xC2, 0xC5, 0xCC, 0xCB,
	0xE6, 0xE1, 0xE8, 0xEF, 0xFA, 0xFD, 0xF4, 0xF3,
};

static int io_bit_count;
static int io_data;

void set_gpx1_2_high(void)
{
	GPX1CON &= ~(0xf << 8);
	GPX1CON |= (1 << 8);
	GPX1DAT |= 1 << 2;
}

void set_gpx1_2_low(void)
{
	GPX1CON &= ~(0xf << 8);
	GPX1CON |= (1 << 8);
	GPX1DAT &= ~(1 << 2);
}

void wait_timeout(void)
{
	while(!(TINT_CSTAT & (1 << 6)));
        TINT_CSTAT |= 1 << 6;
}

void set_backlight_start(int backlight)
{
	unsigned char crc;

	backlight += 0x80;

	//gpio high
	set_gpx1_2_high();

	crc8_init(crc);
	crc8(crc, backlight);
	io_data = (backlight << 8) + crc;
	io_data <<= 16;

	timer1_init();

	set_gpx1_2_low();

	wait_timeout();
	io_bit_count = 16;

	wait_timeout();

	while(io_bit_count){
		if(io_data & (1U << 31))
			set_gpx1_2_high();
		else
			set_gpx1_2_low();

		io_data <<= 1;

		io_bit_count--;
		wait_timeout();
	}

	stop_timer1();
}