Reading data from the FIFO will result in errors after a period of time.

[Herodng]

Thank you for solving my problem. Please forgive my poor English.

I am using lsm6dsl sensor. When I use FIFO to read LSM6DSL, the data is correct at the beginning, but later there will be data errors.

configuration :

• XL_ODR_208Hz
• GY_ODR_208Hz
• FIFO_208Hz
• 2g, 2000dps
• XL_ANA_BW_400Hz
• LOW_NOISE_LP_ODR_DIV_100
• BDU Enable

After my machine is turned on, I will run lsm6dsl_freq_reset first to ensure that my LSM6DSL is at 208Hz, but I will not turn on the FIFO. I will execute lsm6dsl_fifo_set through the serial port to turn on the FIFO. You can refer to the file I uploaded

#define PATTERN_LEN 			 ((3 + 3 + 3)  * 2)
#define LSM_DATA_PACKAGE_NUM	         (10)

void lsm6dsl_fifo_set(void)
{

	uint8_t temp = 0xAA;
	lsm6dsl_int1_route_t int_1_reg;

	/* FIFO配置 */
	//配置FIFO ODR 208Hz
	lsm6dsl_fifo_data_rate_set(&dev_ctx, LSM6DSL_FIFO_208Hz);
	//配置降采样率 为0 按照输出ODR直接存储到FIFO
	lsm6dsl_fifo_gy_batch_set(&dev_ctx, LSM6DSL_FIFO_GY_NO_DEC);
	lsm6dsl_fifo_xl_batch_set(&dev_ctx, LSM6DSL_FIFO_XL_NO_DEC);
	//lsm6dsl_fifo_dataset_3_batch_set(&dev_ctx, LSM6DSL_FIFO_DS3_NO_DEC);


	//配置FIFO阈值 数据量达到该值时触发中断 测得LSM_DATA_PACKAGE_NUM组就发到SDK
	lsm6dsl_fifo_watermark_set(&dev_ctx, PATTERN_LEN * LSM_DATA_PACKAGE_NUM);

	//配置FIFO模式, FIFO_MODE_[2:0]位为001，以启用FIFO模式
	//lsm6dsl_fifo_mode_set(&dev_ctx, LSM6DSL_FIFO_MODE);

    	//timestamp count enabled 使能时间戳
    	lsm6dsl_timestamp_set(&dev_ctx, PROPERTY_ENABLE);

   	lsm6dsl_timestamp_res_set(&dev_ctx, LSM6DSL_LSB_25us);
	//从低时间戳分辨率切换到高分辨率时，必须重置计时器计数
	lsm6dsl_write_reg(&dev_ctx, LSM6DSL_TIMESTAMP2_REG, (uint8_t *)&temp, sizeof(temp));

	lsm6dsl_fifo_dataset_4_batch_set(&dev_ctx, LSM6DSL_FIFO_DS4_NO_DEC);

	//配置阈值中断 enable
	lsm6dsl_pin_int1_route_get(&dev_ctx, &int_1_reg);
	int_1_reg.int1_fth = PROPERTY_ENABLE;
	lsm6dsl_pin_int1_route_set(&dev_ctx,  int_1_reg);
	//当使用 FIFO 时，CTRL3_C寄存器的 IF_INC 位和 BDU 位必须等于 1。
	lsm6dsl_auto_increment_set(&dev_ctx,  PROPERTY_ENABLE);

	//可以在 FIFO 中存储时间戳和 step counter 数据为第 4 个 FIFO 数据集。
	//要使能此功能，必须在 FIFO_CTRL2 寄存器中将  TIMER_PEDO_FIFO_EN bit设置为 1。
	lsm6dsl_fifo_pedo_and_timestamp_batch_set(&dev_ctx, PROPERTY_ENABLE);
	//且 MASTER_CONFIG 的 DATA_VALID_SEL_FIFO 位设置为 0 时
	//数据可以通过两种方式存储在 FIFO 中，具体取决于 FIFO_CTRL2 中 TIMER_PEDO_FIFO_DRDY 位的配置
	//当FIFO_CTRL2 的 TIMER_PEDO_FIFO_DRDY 位设置为 0 时，数据以 FIFO_CTRL5 register 中设置的 ODR_FIFO 速率写入 FIFO。
	lsm6dsl_fifo_write_trigger_set(&dev_ctx, LSM6DSL_TRG_XL_GY_DRDY);
	lsm6dsl_block_data_update_set(&dev_ctx, PROPERTY_ENABLE);
	lsm6dsl_fifo_mode_set(&dev_ctx, LSM6DSL_STREAM_MODE);
}



void lsm6dsl_freq_reset(uint8_t freq)
{
	 uint8_t temp = 0xAA;
	 uint16_t FIFOnum = 0;

	 lsm6dsl_int1_route_t int_1_reg;
	 lsm6dsl_reset_set(&dev_ctx, PROPERTY_ENABLE);

	  do {
      lsm6dsl_reset_get(&dev_ctx, &rst);
    } while (rst);


	xil_printf("lsm6d reset operation over\r\n");
	IMU_FRQ = freq;
	IMU_IRQ = LSM6D_IRQ_OFF;

	if(freq == LSM6D_OFF)
	{
		lsm6dsl_xl_data_rate_set(&dev_ctx, LSM6DSL_XL_ODR_OFF);
    	lsm6dsl_gy_data_rate_set(&dev_ctx, LSM6DSL_GY_ODR_OFF);
    	//在重新启动 FIFO 模式之前，必须先设置为 Bypass 模式，以便完全清除 FIFO 内容。
    	lsm6dsl_fifo_mode_set(&dev_ctx, LSM6DSL_BYPASS_MODE);
    	lsm6dsl_write_reg(&dev_ctx, LSM6DSL_TIMESTAMP2_REG, (uint8_t *)&temp, 1);
    	lsm6dsl_timestamp_set(&dev_ctx, PROPERTY_DISABLE);
		lsm6dsl_data_raw_clean();
		return;
	}
	else if (freq == LSM6D_52Hz)  //80ms     unit loop:80ms    post loop:400ms
	{
		lsm6dsl_xl_data_rate_set(&dev_ctx, LSM6DSL_XL_ODR_52Hz);
    	lsm6dsl_gy_data_rate_set(&dev_ctx, LSM6DSL_GY_ODR_52Hz);
	}
	else if (freq == LSM6D_208Hz)  //4.81      unit loop:5ms    post loop:25ms
	{
		lsm6dsl_xl_data_rate_set(&dev_ctx, LSM6DSL_XL_ODR_208Hz);
    	lsm6dsl_gy_data_rate_set(&dev_ctx, LSM6DSL_GY_ODR_208Hz);
	}
	else if (freq == LSM6D_1k66Hz)  //0.938ms  unit loop:1ms     post loop:5ms
	{
		lsm6dsl_xl_data_rate_set(&dev_ctx, LSM6DSL_XL_ODR_1k66Hz);
    	lsm6dsl_gy_data_rate_set(&dev_ctx, LSM6DSL_GY_ODR_1k66Hz);
	}

	overflow_count = 0;
	data_raw_timestamp_last = 0;
	lsm6dsl_xl_full_scale_set(&dev_ctx, LSM6DSL_2g);
    	lsm6dsl_gy_full_scale_set(&dev_ctx, LSM6DSL_2000dps);
	lsm6dsl_xl_filter_analog_set(&dev_ctx, LSM6DSL_XL_ANA_BW_400Hz);
	lsm6dsl_xl_lp2_bandwidth_set(&dev_ctx, LSM6DSL_XL_LOW_NOISE_LP_ODR_DIV_100);

}

The LSM6DSL output data is normal at the beginning, but the later data will be wrong, the error time is uncertain, it may be a few seconds later, it may be a few minutes or even tens of minutes later

Here is my reading process

//中断处理除了调试外 禁止打印，会影响中断执行
void lsm6dsl_irq_handle(void *callback_ref)
{
	uint8_t  wmflag = 0;
	int64_t  stamp = 0;

	uint16_t fifo_num = 0;							//FIFO存储的个数
	uint16_t num_pattern = 0;
	int16_t  imu_data_all[9] = {0};

	uint64_t data_raw_timestamp_total = 0;	//总时间戳

	XGpioPs *gpio_irq = (XGpioPs *) callback_ref;
	//xil_printf("imu irq!!!!!!\r\n");
	if(IMU_IRQ == LSM6D_IRQ_WKU)
	{
		lsm6dsl_wakeup_handle();
	}
	else if (IMU_IRQ == LSM6D_IRQ_6D)
	{
		lsm6dsl_6d_handle();
	}
	else if (IMU_IRQ == LSM6D_IRQ_FF)
	{
		lsm6dsl_freefall_handle();
	}
	else
	{
		lsm6dsl_fifo_wtm_flag_get(&dev_ctx, &wmflag);
		if (wmflag)
		{
			//温度
			lsm6dsl_status_reg_get(&dev_ctx, &dev_reg.status_reg);
			if (dev_reg.status_reg.tda)
			{
				data_raw_temperature = 0;
				lsm6dsl_temperature_raw_get(&dev_ctx, &data_raw_temperature);
			}
			lsm6dsl_fifo_data_level_get(&dev_ctx, &fifo_num);
			num_pattern = fifo_num / PATTERN_LEN;
			//xil_printf("imu FIFOnum %d!\r\n", FIFOnum);
			// 0：  Gx 1：  Gy  2：Gz  3：XLx  4：XLy  5：XLz  6：Mx  7：My  8：Mz 9: T1 10: T2 11: T3
			// 第11位没有数据 因为时间戳是24位的 但是我们需要一起读出来，不然会fifo错乱
			for (int i=0; i < num_pattern; i++)
			{
				memset(imu_data_all, 0x00, sizeof(imu_data_all));
				lsm6dsl_fifo_raw_data_get(&dev_ctx, imu_data_all, sizeof(imu_data_all));

				//将时间戳从数组中拿出来
				//23-16
				stamp =  (imu_data_all[6] & 0xFF00);
				stamp =  ((stamp <<  & 0xFF0000);
				//15-8
				stamp |= ((imu_data_all[6] <<  & 0xFF00);
				//7-0
				stamp |= ((imu_data_all[7] >>  & 0xFF);

				//xil_printf("stamp : %d!\r\n", (uint32_t)stamp);
				//不能只保证data_raw_timestamp_last > stamp, imu时间戳可能会有偶然一次数据不准
				if (data_raw_timestamp_last > 0xFF0000 && stamp < 0x15000)
				{
					overflow_count++;
					//xil_printf("overflow_count: %d!\r\n", (uint32_t)overflow_count);
				}
				data_raw_timestamp_total = (0x1000000 * overflow_count) + stamp;
				//xil_printf("%d--%d\r\n", (uint32_t)data_raw_timestamp_total, (uint32_t)(data_raw_timestamp_total >> 32));
				data_raw_timestamp_last = stamp;
				lsm6dsl_data_raw_buf(imu_data_all, imu_data_all+3, NULL, data_raw_temperature, &data_raw_timestamp_total);
			}
			//xil_printf("data_raw_timestamp_total : %d!\r\n", (uint32_t)stamp);
		}
	}

	XGpioPs_IntrClearPin(gpio_irq, GPIO_LSM6D_INT);
}

The first three are the ACC data, then the temperature, and finally the timestamp, The temperature data is error-free because it is not read through interrupts and FIFO, but directly from the register:

0.148657 -0.060573 -0.996557 31.8633 "38.79622"
0.148718 -0.060634 -0.996557 31.8633 "38.80108"
0.148718 -0.060634 -0.996618 31.8633 "38.80590"
0.148718 -0.060573 -0.99674 31.8633 "38.81073"
0.148718 -0.060512 -0.996801 31.8633 "38.81555"
0.148779 -0.060451 -0.996801 31.8633 "38.82040"
0.148901 -0.06039 -0.99674 31.8633 "38.82523"
0.148901 -0.060329 -0.996679 31.8633 "38.83005"
0.148962 -0.060329 -0.99674 31.8711 "38.83488"
0.148962 -0.060329 -0.99674 31.8711 "38.83970"
0.148962 -0.060329 -0.99674 31.8711 "38.84455"
0.148962 -0.060268 -0.99674 31.8711 "38.84938"
0.148901 -0.060207 -0.996679 31.8711 "38.85420"
0.14884 -0.060207 -0.996679 31.8711 "38.85903"
0.148779 -0.060207 -0.996618 31.8711 "38.86385"
0.148779 0 -0.000915 31.8711 "419.37918"
-0.046482 0 -0.000976 31.8711 "419.36638"
-1.03029 0 -0.000915 31.8711 "419.37278"
1.9836 0 -0.000976 31.9414 "419.37278"
1.01541 0 -0.000854 31.9414 "419.37278"
0.031598 0 -0.000915 31.9414 "419.37278"
-0.95221 0 -0.000854 31.9414 "419.37918"
-1.93602 0 -0.000915 31.9414 "419.37918"
1.09349 0 -0.000915 31.9414 "419.37278"
0.109678 0 -0.000976 31.9414 "419.37278"
-0.87413 0 -0.000976 31.9414 "419.37918"
-1.85794 0 -0.000976 31.9414 "419.37278"
1.15595 0 -0.000976 31.9414 "419.37918"

I did not show the content of GY, this part is also wrong,If you want to see the detailed data, you can download the file I uploaded to see, the file is wrong after 8047 lines