X5的相机同步方案

1、sensor外部触发曝光

2、lpwm软件触发

软件触发： trigger_mode = 0 ，代表内部软件触发，配置软件触发后， LPWM 驱动将自动提供基于 hrtimer 的周期为 1s 软件 trigger。本质就是 1s 去写一个 LPWM 寄存器 (LPWM_SW_TRIG)，让 LPWM 重新按照配置输出方波。

lpwm属性配置

c 复制代码

.lpwm_attr = {
		.enable = 1,
		.lpwm_chn_attr = {
			{	.trigger_source = 0,
				.trigger_mode = 0,
				.period = 33333,
				.offset = 10,
				.duty_time = 100,
				.threshold = 0,
				.adjust_step = 0,
			},
			{	.trigger_source = 0,
				.trigger_mode = 0,
				.period = 33333,
				.offset = 10,
				.duty_time = 100,
				.threshold = 0,
				.adjust_step = 0,
			},
			{	.trigger_source = 0,
				.trigger_mode = 0,
				.period = 33333,
				.offset = 10,
				.duty_time = 100,
				.threshold = 0,
				.adjust_step = 0,
			},
			{	.trigger_source = 0,
				.trigger_mode = 0,
				.period = 33333,
				.offset = 10,
				.duty_time = 100,
				.threshold = 0,
				.adjust_step = 0,
			},
		},
	},

3、lpwm硬件触发

硬件触发： trigger_mode = 1 ，代表代表外部触发，需要外接一个 PPS (pulse per second) 信号， LPWM 收到 PPS 信号后，硬件会按照软件的配置，输出方波。每收到一个 PPS 信号， LPWM 都会按照配置，重新出波。

检测 pps 信号这里有两种硬件方案，一种是 GPIO 中断，一种配置引脚 Time_Sync 功能

3.1 Time_Sync方案

PWM模拟pps信号，周期为1s

c 复制代码

&pwm2 {
	status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_pwm2_0 &pinctrl_pwm2_1>;
};

c 复制代码

cd /sys/class/pwm/pwmchip0
echo 1 > export
cd pwm1/
echo 1000000000 > period #1s
echo 500000000 > duty_cycle #50%
echo 1 > enable

复用TIME_SYNC1 引脚，作为pps信号输入脚

c 复制代码

&lsio_iomuxc {
	gps_pps_func: gps_pps_func {
        horizon,pins = <
                LSIO_I2C1_SCL        LSIO_PINMUX_2        BIT_OFFSET20        MUX_ALT2        &pconf_input_en_3v3
        >; 
    };
};

c 复制代码

&hobot_pps {
	pinctrl-names = "default";
	pinctrl-0 = <&gps_pps_func>;
	status = "okay";
};

lpwm属性配置

lpwm输出30HZ，触发sensor输出30帧图像

c 复制代码

.lpwm_attr = {
		.enable = 1,
		.lpwm_chn_attr = {
			{	.trigger_source = 7,
				.trigger_mode = 1,
				.period = 33333,
				.offset = 10,
				.duty_time = 100,
				.threshold = 0,
				.adjust_step = 0,
			},
			{	.trigger_source = 7,
				.trigger_mode = 1,
				.period = 33333,
				.offset = 10,
				.duty_time = 100,
				.threshold = 0,
				.adjust_step = 0,
			},
			{	.trigger_source = 7,
				.trigger_mode = 1,
				.period = 33333,
				.offset = 10,
				.duty_time = 100,
				.threshold = 0,
				.adjust_step = 0,
			},
			{	.trigger_source = 7,
				.trigger_mode = 1,
				.period = 33333,
				.offset = 10,
				.duty_time = 100,
				.threshold = 0,
				.adjust_step = 0,
			},
		},