Intermediate
30 min

Measure the distance between the sensor and an object with TMF8828 and STM32F415RG

Detect, respond, repeat.

LightRanger 9 Click with STM32 M4 clicker

Published May 03, 2023

Click board™

LightRanger 9 Click

Dev Board

STM32 M4 clicker

Compiler

NECTO Studio

MCU

STM32F415RG

Multi-zone Time-of-Flight platform with user-presence detection

A

A

Hardware Overview

How does it work?

LightRanger 9 Click is based on the TMF8828, a dToF wide field of view optical distance sensor module with multizone from ams AG. This sensor is built using a single-photon avalanche diode (SPAD) array, time-to-digital converter (TDC), and histogram technology featuring an associated VCSEL, while the high-quality lens on the SPAD supports a dynamically adjustable field of view up to 63°. The TMF8828 detects the target area in multiple zones with precise measurement results, with a minimum distance of 10mm and a maximum of 5m. It can also detect numerous objects per zone, allowing automated robots to gain additional sensory awareness and provide early alerts to potential obstacles. The TMF8828 operating principle uses a pulse train of VCSEL pulses defined by the iteration setting. These pulses are spread using an MLA (microlens array) to illuminate the FoI (illumination field). An object reflects these rays to the TMF8828 receiver optics lens and onto an array of

SPAD (single-photon avalanche detector). A TDC measures the time from the emission of the pulses to their arrival and accumulates the hits into bins inside a histogram. As mentioned before, the TMF8828 comes with a multizone operation. It has two operating modes, a mode with 3x3, 4x4, 3x6 zones, or 8x8 zones, which implements its functionality as a sequence of four time-multiplexed measurements of 4x4 zones. As such, the host must perform the factory calibration sequence, loading the calibration data, reading the result measurements, and the optional histogram readouts four times in series. Also, unique addition to this Click board™ represents an additional 0.7mm thick protective lens alongside a 0.38mm air-gap spacer that separates the lens from the sensor, further reducing interference and improving the sensor's accuracy. LightRanger 9 Click communicates with MCU using the standard I2C 2-Wire interface supporting Fast Mode operation with a clock frequency of 1MHz.

It provides distance information together with confidence values through its serial interface. The internal processor of the TMF8828 (ARM M0+®) executes the AMS algorithm on these histograms to calculate the target distance of the object presented in mm through the I2C interface for each zone. Also, it provides the possibility of the device Power-Up feature (Enable) routed to the CS pin of the mikroBUS™ socket, interrupt feature on the INT pin of the mikroBUS™ to optimize ranging operation, and two pins on the RST and PWM pins of the mikroBUS™ socket used as general-purpose I/O signals. This Click board™ can only be operated from a 3.3V logic voltage level. Therefore, the board must perform appropriate logic voltage conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

LightRanger 9 Click top side image
LightRanger 9 Click lateral side image
LightRanger 9 Click bottom side image

Features overview

Development board

STM32 M4 Clicker is a compact starter development board that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It comes with an onboard 32-bit ARM Cortex-M4 microcontroller, the STM32F415RG from STMicroelectronics, a USB connector, LED indicators, buttons, a JTAG connector, and a header for interfacing with external electronics. Thanks to its compact design with clear and easy-recognizable silkscreen markings, it provides a fluid and immersive working experience, allowing

access anywhere and under any circumstances. Each part of the STM32 M4 Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the STM32 M4 Clicker programming method, using USB HID mikroBootloader, or through an external mikroProg connector for the STM32 programmer, the Clicker board also includes a clean and regulated power supply module for the development kit. The USB Mini-B connection can provide up to 500mA of current, which is more than enough to operate all

onboard and additional modules. All communication methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, reset button, and several buttons and LED indicators. STM32 M4 Clicker is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

STM32 M4 Clicker double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M4

MCU Memory (KB)

1024

Silicon Vendor

STMicroelectronics

Pin count

64

RAM (Bytes)

196608

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
General Purpse I/O
PB5
RST
Enable
PB12
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
General Purpse I/O
PB0
PWM
Interrupt
PB1
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PB10
SCL
I2C Data
PB11
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Schematic

LightRanger 9 Click Schematic schematic

Step by step

Project assembly

STM32 M4 clicker front image hardware assembly

Start by selecting your development board and Click board™. Begin with the STM32 M4 clicker as your development board.

STM32 M4 clicker front image hardware assembly
Thermo 28 Click front image hardware assembly
Prog-cut hardware assembly
STM32 M4 Mini B Connector clicker - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
STM32 M4 Clicker HA MCU/Select Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output via Debug Mode

1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.

2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.

DEBUG_Application_Output

Software Support

Library Description

This library contains API for LightRanger 9 Click driver.

Key functions:

  • lightranger9_get_int_pin This function returns the INT pin logic state.

  • lightranger9_clear_interrupts This function reads and clears the interrupt status register.

  • lightranger9_get_capture This function reads and parses a single sub-capture block of 132 bytes.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * @file main.c
 * @brief LightRanger9 Click example
 *
 * # Description
 * This example demonstrates the use of LightRanger 9 click board by reading and displaying
 * all four sub-captures data measurements on the USB UART.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and performs the click default configuration.
 *
 * ## Application Task
 * Reads all four sub-captures data approximately every 500ms and logs them to the USB UART
 * in a form of two object 8x8 maps. Other data such as DIE temperature, ambient light, system tick, 
 * etc., are also being displayed.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "lightranger9.h"

static lightranger9_t lightranger9;
static log_t logger;

static lightranger9_meas_result_t object_1[ LIGHTRANGER9_OBJECT_MAP_SIZE ];
static lightranger9_meas_result_t object_2[ LIGHTRANGER9_OBJECT_MAP_SIZE ];

/**
 * @brief LightRanger 9 log results function.
 * @details This function parses measurement results to 2 object maps, 
 * and logs the results on the USB UART.
 * @param[in] capture : Capture data object.
 * See #lightranger9_capture_t object definition for detailed explanation.
 * @return None.
 * @note It must be called 4 times for all 4 different input sub-captures.
 */
static void lightranger9_log_results ( lightranger9_capture_t capture );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    lightranger9_cfg_t lightranger9_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    lightranger9_cfg_setup( &lightranger9_cfg );
    LIGHTRANGER9_MAP_MIKROBUS( lightranger9_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == lightranger9_init( &lightranger9, &lightranger9_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( LIGHTRANGER9_ERROR == lightranger9_default_cfg ( &lightranger9 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    while ( lightranger9_get_int_pin ( &lightranger9 ) );

    lightranger9_capture_t capture;
    if ( ( LIGHTRANGER9_OK == lightranger9_clear_interrupts ( &lightranger9 ) ) && 
         ( LIGHTRANGER9_OK == lightranger9_get_capture ( &lightranger9, &capture ) ) )
    {
        lightranger9_log_results ( capture );
    }
}

void main ( void ) 
{
    application_init( );

    for ( ; ; ) 
    {
        application_task( );
    }
}

static void lightranger9_log_results ( lightranger9_capture_t capture )
{
    static uint8_t sub_capture_cnt = 0;
    uint8_t result_cnt = 0, row = 0, col = 0;
    for ( result_cnt = 0; result_cnt < LIGHTRANGER9_MAX_MEAS_RESULTS; result_cnt++ ) 
    {
        if ( 8 == ( result_cnt % 9 ) )
        {
            continue;
        }
        row = ( ( ( result_cnt % 9 ) / 2 ) * 2 ) + ( capture.sub_capture / 2 );
        col = ( ( ( result_cnt % 9 ) % 2 ) * 4 ) + ( ( result_cnt % 18 ) / 9 ) + ( ( capture.sub_capture % 2 ) * 2 );
        if ( result_cnt >= ( LIGHTRANGER9_MAX_MEAS_RESULTS / 2 ) )
        {
            object_2 [ ( row * 8 ) + col ].confidence = capture.result[ result_cnt ].confidence;
            object_2 [ ( row * 8 ) + col ].distance_mm = capture.result[ result_cnt ].distance_mm;
        }
        else
        {
            object_1 [ ( row * 8 ) + col ].confidence = capture.result[ result_cnt ].confidence;
            object_1 [ ( row * 8 ) + col ].distance_mm = capture.result[ result_cnt ].distance_mm;
        }
    }
    if ( sub_capture_cnt < LIGHTRANGER9_SUBCAPTURE_3 )
    {
        sub_capture_cnt++;
        return;
    }
    log_printf ( &logger, "\r\n Result number: %u\r\n", ( uint16_t ) capture.result_number );
    log_printf ( &logger, " DIE temperature: %d C\r\n", ( int16_t ) capture.temperature );
    log_printf ( &logger, " Valid results: %u\r\n", ( uint16_t ) capture.valid_results );
    log_printf ( &logger, " Ambient light: %lu\r\n", capture.ambient_light );
    log_printf ( &logger, " Photon count: %lu\r\n", capture.photon_count );
    log_printf ( &logger, " Reference count: %lu\r\n", capture.reference_count );
    log_printf ( &logger, " Sys tick: %.2f s\r\n", capture.sys_tick_sec );
    log_printf ( &logger, "\r\n Object 1 MAP:\r\n" );
    for ( result_cnt = 0; result_cnt < LIGHTRANGER9_OBJECT_MAP_SIZE; result_cnt++ )
    {
        log_printf ( &logger, " %u\t", object_1[ result_cnt ].distance_mm );
        if ( result_cnt % 8 == 7 )
        {
            log_printf ( &logger, "\r\n" );
        }
    }
    log_printf ( &logger, "\r\n Object 2 MAP:\r\n" );
    for ( result_cnt = 0; result_cnt < LIGHTRANGER9_OBJECT_MAP_SIZE; result_cnt++ )
    {
        log_printf ( &logger, " %u\t", object_2[ result_cnt ].distance_mm );
        if ( result_cnt % 8 == 7 )
        {
            log_printf ( &logger, "\r\n" );
        }
    }
    log_printf ( &logger, "\r\n" );
    
    sub_capture_cnt = 0;
    memset ( object_1, 0, sizeof ( object_1 ) );
    memset ( object_2, 0, sizeof ( object_2 ) );
}

// ------------------------------------------------------------------------ END

Additional Support

Resources

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