Nucleo-L476RG Quick Start (STM32)

All the products described on this page include ESD (electrostatic discharge) sensitive devices. Electrostatic charges as high as 4000V readily accumulate on the human body or test equipment and can discharge without detection. Although the boards feature ESD protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. This includes removing static charge on external equipment, cables, or antennas before connecting to the device.

This guide describes how to use the EVAL-AD7124-4SDZ or EVAL-AD7124-8SDZ evaluation board with the STM32 Nucleo-L476RG using STM32CubeIDE. The general procedure can be applied to other STM32 processors and IDEs.

Important

The example code was developed and tested using the Nucleo-L476RG with version 1.14.0 of the STM32 firmware libraries, and STM32CubeIDE v1.0.0. It may be retargeted to other STM32 processors/boards through the use of appropriate ST firmware HAL libraries. <web>

Prerequisites

See Prerequisites for the full list.

Hardware:

EVAL-AD7124-4SDZ or EVAL-AD7124-8SDZ evaluation board
STM32 Nucleo-L476RG
SDP Breakout Board (for convenient SPI connections)
7–9 V DC power supply for the evaluation board
Micro USB cable

Software:

STM32CubeIDE

Download

ad7124_stm32_example.zip <web>

Software integration guide

Project creation

Install STM32CubeIDE if not already installed.
In the Firmware Update section of STM32CubeIDE preferences, set the firmware package storage location (e.g., C:\ST\Repository).

Tip

Place this in a common location, not under your home directory, to avoid user-specific paths in shared configuration files.
Select File >> New >> STM32 project.
Select the MCU part number or board (Nucleo-L476RG).
Give the project a name, select target language, and project type of STM32Cube.
Verify the Target Reference and firmware package repository path. Set the Code Generator Options to reference or copy library files as desired.
Click Finish. STM32CubeIDE will download and unzip the firmware library (typically hundreds of MB; this takes several minutes).

Device configuration

The Device Configuration Tool with automatic code generation defines pin usage and default modes of operation for the Nucleo-L476RG.

Important

The pins and configuration provided here need to be tailored to the specific board/processor being used.

SPI configuration

SPI1 port is used to communicate with the AD7124. Pin PB10 is used as a software-controlled chip select for SPI1. Its mode must be set to GPIO_output with user label SPI1_NSS to match the platform driver file.

Tip

It is recommended to use a pull-up resistor on the SPI MOSI to ensure it is never floating in an undefined logic state. This can be a resistor on the board to the logic supply, or internal to the processor if available.

DMA and interrupts are not used and do not need to be configured.

Serial UART configuration

The serial port uses USART2. No DMA or interrupts need to be configured.

GPIO configuration

An LED is toggled on the Nucleo-L476RG to indicate sampling activity. The activity LED is controlled by Port A, Pin 5, and needs to be enabled as a digital output.

Build settings

The printf() function is used to print floating-point values in the terminal. As this feature is often disabled by default, floating-point support must be enabled:

In Project Properties >> C/C++ Build >> Settings >> MCU GCC Linker >> Miscellaneous >> Other Flags, add -u _printf_float.

Tip

There is also a checkbox option in the MCU Settings view. Enabling it in the linker section prevents the code analysis feature from reporting %f as unsupported.

Linker files

The default value for _estack may be incorrect in the .ld files. This can cause printf() with %f to output 0.00 instead of the correct value.

For the Nucleo-L476RG, change:

/* Highest address of the user mode stack */
_estack = 0x20017fff; /* end of "RAM" Ram type memory */

to:

/* Highest address of the user mode stack */
_estack = 0x20018000; /* end of "RAM" Ram type memory */

Source file edits

main.c

Add the following to integrate the AD7124 example application:

#include "ad7124_console_app.h"

/* Initialize the AD7124 application before the main loop */
int32_t setupResult;
if ((setupResult = ad7124_app_initialize(AD7124_CONFIG_A)) < 0) {
    // Handle error setting up AD7124 here
}

while(1) {
    // display the console menu for the AD7124 application
    adi_do_console_menu(&ad7124_main_menu);
}

main.h

Add extern declarations for the SPI and serial port handles:

extern SPI_HandleTypeDef hspi1;
extern UART_HandleTypeDef huart2;

Important

The names of the port handles are defined by the Device Configuration Tool based on the selected processor and pin choices. If using a different processor or pins, these may need to be changed in platform_drivers.c and platform_support.c.

syscalls.c

In the _read() function, the len parameter may always be 1024. To support getchar(), add len = 1; immediately before the for loop. This does not support other stdio.h functions such as scanf().

Adding AD7124 example files

Add the AD7124 source and header files from the distribution to the project. Files can be placed in a dedicated adi directory, or in the main src directory, or split between src and inc directories. If adding new source/header locations, add them to the build settings in the relevant Include paths in the MCU GCC Compiler configuration.

Important

The platform_support.c/.h files provide io_getchar() and io_putchar() for serial I/O. If using a compiler other than GCC or a different serial port than USART2, additional changes may be required.

Hardware connections

Power and USB

A 9 V DC supply (barrel jack, center pin positive) is required to power the EVAL-AD7124-4SDZ evaluation board. The Nucleo-L476RG is powered via the USB connection to the PC, which also provides the serial UART connection.

Tip

If you are unsure which COM port to use, open Device Manager and look under the Ports (COM & LPT) node.

SPI interface

SPI connections from the EVAL-AD7124-4SDZ to the Nucleo-L476RG can be made via the SDP Breakout Board.

Table 1 SPI Wiring (via SDP Breakout Board)
AD7124 SPI Signal	SDP Breakout Board Pin	Nucleo-L476RG Pin
GND	81	GND on CN5.7
SCLK	82	D3 (PB3) on CN9.4
DOUT/RDYB	83	D5 (PB4) on CN9.6
DIN	84	D4 (PB5) on CN9.5
CSB	85	D6 (PB10) on CN9.7

Analog inputs

The screw terminal connections on J6 and J11 on the EVAL-AD7124-4SDZ board can be used to connect analog input signals.

Configuration A:

AIN0/AIN1 are used for channel 0, simple voltage measurement

Configuration B:

AIN2/AIN3 connect to the A2 thermocouple connector (channel 0, internal reference, bias voltage on AIN2)
AIN4/AIN5 are an RTD1000 measurement on channel 1 (excitation from AIN1, requires external RTD and reference resistor)

Console application

Once the hardware connections are made and the compiled code is programmed into the board, open a terminal program and reset the hardware to see the AD7124 menu. The menu allows:

Resetting the device
Programming pre-defined configurations
Sampling data displayed on screen or streamed for capture