The best available custom ADC solution with ADS131M02 and ATmega328P
Go digital with ADC!
Published Feb 14, 2024
Click board™
ADC 15 Click
Dev Board
Arduino UNO Rev3
Compiler
NECTO Studio
MCU
ATmega328P
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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
Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an
ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the
first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.
Microcontroller Overview
MCU Card / MCU
Architecture
AVR
MCU Memory (KB)
32
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
2048
You complete me!
Accessories
Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P 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 Arduino UNO board with our Click Shield for Arduino UNO, 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 Arduino UNO Rev3 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
The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.
/*!
* @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
