This page gives an overview of using the AD7124 Firmware Example with SDP-K1 EVAL board and AD7124 EVAL board. The firmware example comprises 3 layers of software (from top to bottom): Console Application Layer, Device No-OS Layer and Platform Drivers (Mbed-OS) layer.
The application layer uses the ADI Console Libraries to create console based User Interactive (UI). The middle layer of No-OS device library have device specific APIs to interface with AD7124 device. These APIs allows direct access to device register map in order to read/write device registers. The bottom layer of Platform Drivers is responsible for Low Level Interface. The platform drivers uses mbed-os libraries to access low level peripheral (like GPIOs, SPI, I2C, etc).
The Mbed Platform simplifies the overall software development process by providing the low level driver support. This reduces the hardware dependency as any Mbed enabled board can be used with same firmware with little modifications (precisely changing a pin mapping).
The AD7124-EVAL board is connected to SDP-K1 through default 120-pin SDP Connector. The AD7124-EVAL board has external connector to connect up-to 8 analog inputs. The board needs to be powered-up through 9-12V external DC supply. The SDP-K1 is connected to PC through USB cable. The firmware can be loaded into SDP-K1 board through this USB interface from PC. The SDP-K1 acts as a Serial Device and firmware loaded into it interacts with any serial terminal (like Teraterm, Putty, Coolterm, etc) by configuring terminal for proper serial settings (COM Port, Baud Rate, etc).
A 7V to 9V DC supply (barrel jack, center pin positive) is required to power the EVAL-AD7124-8SDZ evaluation board. SDP-K1 is powered through USB connection to PC. SDP-K1 acts as a Serial device when connected to PC, which creates a COM Port to connect to Serial Terminals like Teraterm, Putty, etc. The COM port assigned to a device can be seen through the device manager for windows based OS.
The screw terminal connections to J6 and J11 can be used to connect appropriate analog input signals to provide test stimulus to the AD7124.
The AD7124 device can be software configured to interface with external devices (e.g. sensors). The AD7124 Firmware example provides such 2 configurations (selected through console UI) as described below:
AIN0/AIN1 are used for channel 0, simple voltage measurement
AIN2/AIN3 go to the A2 thermocouple connector on the evaluation board, and are captured on channel 0. This uses an internal reference and has a bias voltage enabled on AIN2. A suitable thermocouple should be connected to A2 for this measurement. AIN4/AIN5 are an RTD1000 measurement on channel 1. Excitation is provided from AIN1 for this. This requires an external RTD and reference resistor connected as show in the figure below.
Temperature sensing application using AD7124: https://www.analog.com/media/en/reference-design-documentation/reference-designs/CN0383.pdf
This section briefs on the usage of MBED firmware. This also explains the steps to compile and build the application using mbed and make based build.
Source code is hosted here:
Build Guide for Precision Converters MBED firmware (Use below link):
The software execution sequence for the AD7124 Firmware Example is shown below. This is a blocking application as it waits for user input over serial interface (UART). The input is scanned and processed through 'adi console libraries'. The menu functionality is executed from ad7124_conole_app.c file. The application layer talks with No-OS layer for device registers and data access. The No-OS layer interfaces with Platform Drivers layer for accessing low level peripherals. As name suggests, this layer is platform dependent. AD7124 firmware uses Mbed libraries within Platform Drivers layer.
If you have some familiarity with the Mbed platform, the following is a basic list of steps required to start running the code, see below for more detail:
The AD7124 firmware example is configured to have following serial settings:
Configure your serial terminal ( Tera Term) for below settings:
The firmware is designed to be intuitive to use, and requires little explanation, simply enter a number corresponding to the required command and follow the on-screen prompts.
The console menu application provides the following main features: