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VL53L8CX: Histograms manipulation and Interpretation.
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2025-04-09 6:28 AM
Hello Everyone,
I am currently working on a project to determine if it is possible to differentiate between a glass cup and other types of cups using VL53L8CX sensor data histograms, and also to detect the fill level. I have already collected data from the sensor using Example 12 provided in the Ultra Lite Driver, and I have written a small Python script to visualize my data.
My first challenge is switching between the 4x4 histogram data format and the 8x8 format. The second challenge is interpreting the incoming bins_data to understand the differences between, for example, a ceramic cup (which is already possible using just the distance data) and an empty glass cup (using the histogram data to make a distinction, detect the edge, and determine the fill level). Here below is my code stmIDE Code
//__________MY CODE ___________
p_dev.platform.address = 0x52;
Reset_Sensor();
if (status != VL53LMZ_STATUS_OK){
printf("vl53lmz_init failed : %d\n");
return status;
}
/* (Mandatory) Initialise the VL53LMZ sensor */
status = vl53lmz_init(&p_dev);
if(status)
{
printf("VL53LMZ ULD Loading failed\n");
return status;
}
printf("VL53LMZ ULD ready ! (Version : %s)\n",
VL53LMZ_API_REVISION);
status = vl53lmz_set_resolution(&p_dev, 64);
status |= vl53lmz_set_ranging_mode(&p_dev, VL53LMZ_RANGING_MODE_AUTONOMOUS);
status |= vl53lmz_set_ranging_frequency_hz(&p_dev, 5);
status |= vl53lmz_set_integration_time_ms(&p_dev, 20);
if(status)
{
printf("ERROR - Failed basic configuration sequence, status=%u\n", status);
return status;
}
status = vl53lmz_cnh_init_config( &cnh_config,
0, /* StartBin */
18, /* NumBins */
4 ); /* SubSample */
if (status != VL53LMZ_STATUS_OK){
printf("VL53LMZ CNH init config failed\n");
return status;
}
status = vl53lmz_cnh_create_agg_map( &cnh_config,
64, /* Resolution. Must match value used in vl53lmz_set_resolution() */
0, /* StartX */
0, /* StartY */
1, /* MergeX */
1, /* MergeY */
4, /* Cols */
4 ); /* Rows */
if (status != VL53LMZ_STATUS_OK){
printf("VL53LMZ CNH set aggregate map failed\n");
return status;
}
status = vl53lmz_cnh_calc_required_memory( &cnh_config, &cnh_data_size );
if (status != VL53LMZ_STATUS_OK){
printf("VL53LMZ CNH calc required memory failed\n");
if (cnh_data_size < 0){
printf("Required memory is too high : %d. Maximum is %d!\n", (int)-cnh_data_size, (int)VL53LMZ_CNH_MAX_DATA_BYTES);
}
return status;
}
/* Send this CNH configuration to the sensor. */
status = vl53lmz_cnh_send_config(&p_dev,&cnh_config);
if (status != VL53LMZ_STATUS_OK){
printf("VL53LMZ CNH send config failed\n");
return status;
}
/* First create the standard data upload(output) configuration. */
status = vl53lmz_create_output_config(&p_dev);
if (status != VL53LMZ_STATUS_OK){
printf("VL53LMZ CNH create output config failed\n");
return status;
}
/* Next, add the CNH data block, sized correctly for the configuration we are using. */
union Block_header cnh_data_bh;
cnh_data_bh.idx = VL53LMZ_CNH_DATA_IDX;
cnh_data_bh.type = 4;
cnh_data_bh.size = cnh_data_size / 4;
status = vl53lmz_add_output_block(&p_dev, cnh_data_bh.bytes);
if (status != VL53LMZ_STATUS_OK){
printf("VL53LMZ CNH add output block failed\n");
return status;
}
status = vl53lmz_send_output_config_and_start(&p_dev);
printf("Started ranging\n");
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
// __________________ MY CODE _______________
uint8_t buffer[512];
uint8_t *ptr = buffer;
size_t buffer_index = 0; // To keep track of the actual size of the data
status = vl53lmz_check_data_ready(&p_dev, &isReady);
if (isReady)
{
vl53lmz_get_ranging_data(&p_dev, &Results);
printf("Print data no : %3u\n", p_dev.streamcount);
for (i = 0; i < 64; i++)
{
uint16_t zone = i;
uint16_t distance = Results.distance_mm[VL53LMZ_NB_TARGET_PER_ZONE * i];
/*
memcpy(ptr + buffer_index, &zone, sizeof(uint16_t));
buffer_index += sizeof(uint16_t);
memcpy(ptr + buffer_index, &distance, sizeof(uint16_t));
buffer_index += sizeof(uint16_t);
*/
printf("Zone : %3d, Status : %3u, Distance : %4d mm\n",
i,
Results.target_status[VL53LMZ_NB_TARGET_PER_ZONE * i],
distance);
}
status = vl53lmz_results_extract_block(&p_dev, VL53LMZ_CNH_DATA_IDX, (uint8_t *)cnh_data_buffer, cnh_data_size);
if (status != VL53LMZ_STATUS_OK)
{
printf("ERROR at %s(%d) : vl53lmz_results_extract_block failed : %d\n", __func__, __LINE__, status);
return status;
}
for (agg_id = 0; agg_id < cnh_config.nb_of_aggregates; agg_id++)
{
vl53lmz_cnh_get_block_addresses(&cnh_config,
agg_id,
cnh_data_buffer,
&(p_hist), &(p_hist_scaler),
&(p_ambient), &(p_ambient_scaler));
amb_value = ((float)*p_ambient) / (2 << *p_ambient_scaler);
printf("Agg, %2d, Ambient, % .1f, Bins, ", agg_id, amb_value);
for (bin_num = 0; bin_num < cnh_config.feature_length; bin_num++)
{
bin_value = ((float)p_hist[bin_num]) / (2 << p_hist_scaler[bin_num]);
printf("% .1f, ", bin_value);
}
/*
uint16_t Agg_id = agg_id;
float ambient = amb_value;
float bins_val = bin_value;
memcpy(ptr + buffer_index, &Agg_id, sizeof(uint16_t)); buffer_index += sizeof(uint16_t);
memcpy(ptr + buffer_index, &ambient, sizeof(float)); buffer_index += sizeof(float);
memcpy(ptr + buffer_index, &bins_val, sizeof(float)); buffer_index += sizeof(float);
*/
// Now transmit only the actual data in the buffer
//HAL_UART_Transmit(&huart2, sizeof(buffer) , buffer, HAL_MAX_DELAY) ;
printf("\n");
}
loop++;
}
// Wait a few ms to avoid too high polling
// WaitMs(&(p_dev.platform), 5);
HAL_MAX_DELAY;
}
}
And here is the example of what the sensor give me i only have bins_data for 16 zone and not 64 as expected and i am also thinking that i am getting wrong distance value
Zone : 0, Status : 5, Distance : 6472 mm
Zone : 1, Status : 5, Distance : 6716 mm
Zone : 2, Status : 5, Distance : 6678 mm
Zone : 3, Status : 5, Distance : 6662 mm
Zone : 4, Status : 5, Distance : 6486 mm
Zone : 5, Status : 5, Distance : 6526 mm
Zone : 6, Status : 5, Distance : 6516 mm
Zone : 7, Status : 5, Distance : 6535 mm
Zone : 8, Status : 5, Distance : 6475 mm
Zone : 9, Status : 5, Distance : 6506 mm
Zone : 10, Status : 5, Distance : 6513 mm
Zone : 11, Status : 5, Distance : 6556 mm
Zone : 12, Status : 5, Distance : 6577 mm
Zone : 13, Status : 5, Distance : 6559 mm
Zone : 14, Status : 5, Distance : 6597 mm
Zone : 15, Status : 5, Distance : 6622 mm
Zone : 16, Status : 5, Distance : 6474 mm
Zone : 17, Status : 5, Distance : 6529 mm
Zone : 18, Status : 5, Distance : 6611 mm
Zone : 19, Status : 5, Distance : 6613 mm
Zone : 20, Status : 5, Distance : 6623 mm
Zone : 21, Status : 5, Distance : 6630 mm
Zone : 22, Status : 5, Distance : 6650 mm
Zone : 23, Status : 5, Distance : 6650 mm
Zone : 24, Status : 5, Distance : 6527 mm
Zone : 25, Status : 5, Distance : 6596 mm
Zone : 26, Status : 5, Distance : 6641 mm
Zone : 27, Status : 5, Distance : 6702 mm
Zone : 28, Status : 5, Distance : 6720 mm
Zone : 29, Status : 5, Distance : 6732 mm
Zone : 30, Status : 5, Distance : 6709 mm
Zone : 31, Status : 5, Distance : 6673 mm
Zone : 32, Status : 5, Distance : 6592 mm
Zone : 33, Status : 5, Distance : 6598 mm
Zone : 34, Status : 5, Distance : 6687 mm
Zone : 35, Status : 5, Distance : 6731 mm
Zone : 36, Status : 5, Distance : 6744 mm
Zone : 37, Status : 5, Distance : 6730 mm
Zone : 38, Status : 5, Distance : 6745 mm
Zone : 39, Status : 5, Distance : 6735 mm
Zone : 40, Status : 5, Distance : 6591 mm
Zone : 41, Status : 5, Distance : 6644 mm
Zone : 42, Status : 5, Distance : 6705 mm
Zone : 43, Status : 5, Distance : 6768 mm
Zone : 44, Status : 5, Distance : 6799 mm
Zone : 45, Status : 5, Distance : 6789 mm
Zone : 46, Status : 5, Distance : 6790 mm
Zone : 47, Status : 5, Distance : 6804 mm
Zone : 48, Status : 5, Distance : 6610 mm
Zone : 49, Status : 5, Distance : 6667 mm
Zone : 50, Status : 5, Distance : 6754 mm
Zone : 51, Status : 5, Distance : 6766 mm
Zone : 52, Status : 5, Distance : 6789 mm
Zone : 53, Status : 5, Distance : 6815 mm
Zone : 54, Status : 5, Distance : 6749 mm
Zone : 55, Status : 9, Distance : 6716 mm
Zone : 56, Status : 5, Distance : 1542 mm
Zone : 57, Status : 5, Distance : 1646 mm
Zone : 58, Status : 5, Distance : 6635 mm
Zone : 59, Status : 9, Distance : 6472 mm
Zone : 60, Status : 5, Distance : 6491 mm
Zone : 61, Status : 5, Distance : 5826 mm
Zone : 62, Status : 5, Distance : 5588 mm
Zone : 63, Status : 9, Distance : 5293 mm
Agg, 0, Ambient, 1.3, Bins, -1.3, -1.2, -0.6, 0.3, 0.3, -0.1, -0.1, 0.0, -0.0, -0.1, -0.1, 7.8, 13.0, 6.3, -0.4, -0.3, -0.1, -0.2,
Agg, 1, Ambient, 2.9, Bins, -2.9, -2.8, 0.1, 0.1, -0.4, 0.3, -0.6, 0.1, -0.0, -0.3, -0.1, 4.3, 13.0, 7.3, 1.1, -0.2, 0.1, -0.2,
Agg, 2, Ambient, 4.0, Bins, -4.0, -3.3, 0.2, -0.1, 0.2, -0.7, -0.1, 0.4, -0.4, -0.7, -0.9, 7.8, 11.9, 4.3, -0.4, -0.2, 0.1, -0.5,
Agg, 3, Ambient, 4.7, Bins, -4.7, -3.8, -0.4, 0.2, -0.0, 0.1, 0.4, -0.3, -0.7, -0.7, 2.0, 9.8, 12.7, 5.8, -0.6, -0.4, -0.5, -0.4,
Agg, 4, Ambient, -0.9, Bins, -0.9, -0.9, 0.4, -0.1, -0.2, -0.2, -0.3, -0.1, -0.0, -0.2, -0.9, 12.2, 15.9, 2.8, 0.0, 0.1, -0.4, -0.3,
Agg, 5, Ambient, 1.2, Bins, -1.2, -1.2, 0.3, -0.3, -0.4, 0.2, 0.2, 0.2, -0.2, -0.5, 2.1, 16.7, 14.0, 1.8, -0.3, -0.2, 0.4, -0.1,
Agg, 6, Ambient, 1.3, Bins, -1.3, -1.3, -0.5, 0.2, -0.0, -0.6, -0.1, -0.6, 0.1, -0.0, 6.0, 17.2, 10.6, 1.6, -0.4, 0.1, 0.1, -0.3,
Agg, 7, Ambient, 1.1, Bins, -1.1, -1.1, 0.0, -0.1, 0.0, -0.1, -0.5, -0.3, 0.1, -0.2, 6.2, 17.9, 12.3, 1.2, -0.3, -0.3, 0.0, -0.6,
Agg, 8, Ambient, 1.5, Bins, -1.5, -1.5, 0.4, 0.0, 0.1, 0.2, 0.3, 0.3, -0.5, -0.1, 1.5, 13.9, 12.2, 1.6, -0.2, 0.2, -0.0, 0.2,
Agg, 9, Ambient, 1.1, Bins, -1.1, -1.1, 0.1, -0.1, -0.1, -0.2, -0.3, -0.1, -0.1, -0.5, 4.7, 16.5, 12.1, 1.2, -0.7, -0.3, -0.1, -0.6,
Agg, 10, Ambient, 4.9, Bins, -4.9, -3.3, 0.3, 0.5, 0.0, -0.7, -0.5, -0.3, -0.6, -0.4, 5.2, 17.9, 10.0, 1.5, 0.0, -0.6, -0.9, -0.3,
Agg, 11, Ambient, -0.7, Bins, -0.7, -0.7, -0.1, 0.0, -0.0, -0.2, 0.2, -0.1, 0.1, -0.3, 6.8, 19.0, 10.3, -0.9, -0.2, -0.2, 0.2, -0.4,
Agg, 12, Ambient, -0.8, Bins, -0.8, -0.8, 0.1, 0.0, 0.2, 0.2, -0.2, 0.2, -0.2, 0.0, 2.7, 15.2, 13.3, 1.3, -0.2, 0.1, 0.2, -0.0,
Agg, 13, Ambient, 1.3, Bins, -1.3, -1.3, 0.2, -0.1, 0.2, -0.1, 0.3, -0.0, 0.0, 0.1, 5.0, 16.9, 11.5, 1.3, -0.1, 0.3, -0.1, -0.0,
Agg, 14, Ambient, 1.3, Bins, -1.3, -1.2, 0.1, -0.1, -0.2, 0.0, 0.4, 0.4, -0.1, -0.1, 8.4, 19.3, 10.1, 1.1, -0.6, 0.0, -0.3, 0.1,
Agg, 15, Ambient, -0.9, Bins, -0.9, -0.9, 0.3, 0.0, -0.2, -0.1, -0.2, 0.0, 0.1, 0.1, 8.3, 18.1, 9.7, 2.0, -0.6, -0.1, -0.3, -0.3,
Labels:
- Labels:
-
Ambient light
-
Time of flight
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