The best available custom ADC solution with ADS131M02 and STM32G474RE
Go digital with ADC!
Published Nov 08, 2024
Click board™
ADC 15 Click
Dev Board
Nucleo 64 with STM32G474RE MCU
Compiler
NECTO Studio
MCU
STM32G474RE
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Hardware Overview
How does it work?
ADC 15 Click is based on the ADS131M02, a low-power, two-channel, simultaneously sampling, 24-bit, delta-sigma (ΔΣ) analog-to-digital converter (ADC) with a low-drift internal reference voltage from Texas Instruments. The dynamic range, size, feature set, and power consumption are optimized for cost-sensitive applications requiring simultaneous sampling. An integrated negative charge pump allows absolute input voltages as low as -1.3V, enabling input signal measurements varying around the ground with a single-ended power supply. The ADS131M02 features a programmable gain amplifier (PGA) with gains up to 128. An integrated input pre-charge buffer enabled at gains greater than 4 ensures high input impedance at high PGA gain settings. The ADC receives its reference voltage from an integrated 1.2V reference, allowing differential input voltages as large as the reference. Each channel on the ADS131M02 contains a digital
decimation filter that demodulates the output of the ΔΣ modulators. The filter enables data rates as high as 32kSPS per channel in high-resolution mode. The relative phase of the samples can be configured between channels, thus allowing an accurate compensation for the sensor phase response. Offset and gain calibration registers can be programmed to automatically adjust output samples for measured offset and gain errors. The ADC 15 Click communicates with MCU through a standard SPI interface to read the conversion data and configure and control the ADS131M02, supporting the most common SPI mode - SPI Mode 1. To normally run the ADS131M02, an LVCMOS clock must be continuously provided at the CLKIN pin, which is achieved with the LTC6903 programmable oscillator activated via the CS2 pin routed to the PWM pin on the mikroBUS™ socket. The frequency of the clock can be scaled in conjunction
with the power mode to provide a trade-off between power consumption and dynamic range. Selection of the bits in the CLOCK register allows the device to be configured in one of three power modes: high-resolution (HR) mode, low-power (LP) mode, and very low-power (VLP) mode. In addition, this Click board™ also uses features such as data-ready/interrupt routed to the INT pin on the mikroBUS™ socket, which serves as a flag to the host to indicate that new conversion data are available and Reset routed to the RST pin that allows for a hardware device reset. This Click board™ can only be operated with a 3.3V logic voltage level. The board must perform appropriate logic voltage level 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.
Features overview
Development board
Nucleo-64 with STM32G474R MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin
headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is
provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
512
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
128k
You complete me!
Accessories
Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the STM32 Nucleo-64 board with our Click Shield for Nucleo-64, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Nucleo 64 with STM32G474RE MCU as your development board.
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.
Software Support
Library Description
This library contains API for ADC 15 Click driver.
Key functions:
adc15_read_voltageGet voltage value.adc15_set_gainSet gain for channel.adc15_set_word_lenSet word len.
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 ADC15 Click example
*
* # Description
* This example showcases ability of the click board to
* read adc data from 2 different channels. It's also configuratable
* to read data in different output rate, resolutions( word/data len ),
* and gain.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialization of communication modules (SPI, UART) and additional
* pins for control of the device. Sets default configuration, that
* sets gain of 1 for both channels(+/-1.2V range) and word/data length
* of 24bit. In the end reads device ID.
*
* ## Application Task
* Waits for data ready signal and reads voltage value of both channels,
* and logs read status and channel voltage level.
*
* @author Luka Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "adc15.h"
#include "math.h"
static adc15_t adc15;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
adc15_cfg_t adc15_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.
adc15_cfg_setup( &adc15_cfg );
ADC15_MAP_MIKROBUS( adc15_cfg, MIKROBUS_1 );
err_t init_flag = adc15_init( &adc15, &adc15_cfg );
if ( SPI_MASTER_ERROR == init_flag )
{
log_error( &logger, " Communication Init. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
if ( adc15_default_cfg ( &adc15 ) )
{
log_error( &logger, " Default configuration. " );
for( ; ; );
}
uint16_t reg_val;
adc15_reg_read( &adc15, ADC15_REG_ID, ®_val );
log_printf( &logger, " > ID: 0x%.4X\r\n", reg_val );
log_info( &logger, " Application Task " );
Delay_ms ( 1000 );
}
void application_task ( void )
{
while ( adc15_data_ready( &adc15 ) );
float channel1 = 0;
float channel2 = 0;
uint16_t status = 0;
if ( !adc15_read_voltage( &adc15, &status, &channel1, &channel2 ) )
{
log_printf( &logger, " > Status: 0x%.4X\r\n", status );
log_printf( &logger, " > V ch1: %.3f\r\n", channel1 );
log_printf( &logger, " > V ch2: %.3f\r\n", channel2 );
log_printf( &logger, "************************\r\n" );
Delay_ms ( 1000 );
}
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
