Discovering the STM32 CUBE IDE Part 4: Data logger

2023-12-06 | By DWARAKAN RAMANATHAN

License: General Public License ARM mbed

Introduction:

Learn how to effectively capture data from an input device using STM32 Cube IDE. This blog explains the basics of data logging, its benefits, and how to implement it in your STM32 microcontroller projects for better insights and troubleshooting.

Note: This is the continuation of the previous blog of this series. I would request you to review the first three blogs before continuing.

First blog: Discovering the STM32 CUBE IDE: A Simple LED Blink and GPIO Project

Second blog: Discovering the STM32 CUBE IDE Part 2: Learning the UART

Third blog: Discovering the STM32 CUBE IDE Part 3: Interfacing Analog Audio Device

Creating New Project:

To create a project, go to File > New Project. There will be a new window opened for you to select the board or MCU. In this project, we will use B-L4S5I-IOT01A the part is also linked below. Go to Board Selector and select the board by typing in the commercial part number (B-L4S5I-IOT01A) and click Next.

Board Selector

After clicking Next, type the project name (In this case: Audio_logger) and click on Finish.

Project Name

After clicking finish, the STM32 CUBE IDE will automatically download the software packages that your board requires. After the download is complete you will see a workspace something like this (a .ioc file will be opened):

ioc file

Assigning ports:

In this project, we will be sending messages to our console from the device (STM32 Board). STM32 Board uses UART-based communication. Now, to enable UART in your board go to connectivity > USART1 and check if it is in Asynchronous Mode. Now, you will see a warning symbol near USART1. To remove that please reset PB3, PB4, and PB5. After doing so, you will see that the warning is now gone, and a green tick near the USART1 is visible.

UART

Also, you need to use one of the Analog to Digital Converters present in the device. So, to utilize one of the ADC we need to enable it also with the UART. To do so, go to Analog and Enable only the first ADC to IN-1 Single-Ended.

ADC

Generating code:

As you have completed assigning the ports you can generate the code. Click Ctrl+S to save the file and then generate code by going to Project > Generate Code.

After Generating the code, you will have to edit three sections:

The User Include Section
The Private Macro Section
The Private Variables Section
The Private Functions Section
The User Code Begin 3 Inside the while loop
The User Code Begin 4

The codes of each section are given below:

1. The User Include Section

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#include "stdio.h"
#include "string.h"

include

2. The Private Macro Section

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#define DATA_INPUT_USER 512
#define AXIS_NUMBER 1

Define

3. The Private Variables Section

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float mic_data[DATA_INPUT_USER * AXIS_NUMBER] = {0};

Variables

4. The Private Functions Sections

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void fill_mic();
void Log();

Private Functions

5. The User Code Begin 3 inside while loop

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Log();

Log

6. The User Code Begin 4

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void fill_mic() {
	for (int i = 0; i < DATA_INPUT_USER; i++) {
		mic_data[AXIS_NUMBER * i] = HAL_ADC_GetValue(&hadc1);
	}
}

void Log(){
	HAL_ADC_Start(&hadc1);
	fill_mic();
	for (int i = 0; i < DATA_INPUT_USER; i++) {
		printf("%.2f",mic_data[AXIS_NUMBER * i]);
		printf(" ");
	}
	printf("\r\n");
	HAL_Delay(500);
}
int __io_putchar(int ch){
	HAL_UART_Transmit(&huart1, (uint8_t *) &ch, 1, HAL_MAX_DELAY);
	return ch;
}

Code

Understanding: The Include section is filled with stdio.h and string.h libraries because we are using both print statements as well as string datatype. The private variables section is added because we need a variable to store the data from the analog device, and the variable is an array. The private macro section defines 2 variables, data input user, and axis number. The data input is the number of data inputs in a single line, and the axis number is the number of axis of the input (An accelerometer will have three axis x, y, and z).

The User Code Begin 3 is the actual code that will run on the microcontroller device. The User Code Begin 4 is for transmitting characters (data) from the microcontroller to the console using UART and for two main functions of the projects. The log code is used to create the data log, and the fill mic is used to fill the array with the data inputs.

Removing the printf error:

Whenever you try to use printf or scanf statement there will be a compiler error, which simply means that the compiler does not allow using printf or scanf. So, to allow the compiler to recognize them, right-click on the project > Properties > C/C++ Build > Settings > MCU Settings and select both scanf and printf statements. The code will now look good.

printf

Click on Apply and Close.

Connections:

Building and Debugging:

To build the project go to Project > Build Project. If you see no errors, then the code is ready to be debugged.

Build

After building the project connect your microcontroller board and check the communication port in the device manager (Ex: COM7). The device name, in my case, can be different from yours. Do not panic; just check for the port number for any STM-based device.

COM

In this case, the port is 3. Now, debug the main.c file and check whether the console shows "Download verified successfully".

Run

After debugging the code, you should use the ability of the device to use UART to send messages to your console, and for that, you have to create a console mentioning the port that your device is connected to. To do so, go to the console window below the workspace and select Command shell console under Open Console.

Result

After clicking on it, you will see a new window opened for you to choose the port and name of the console. The connection type is serial port and click on "New".

Serial Port

After clicking New, type the name of your port, select the serial port to which your device is connected, and click Finish.

Com

After clicking finish, you will see a new console created for you, and it will tell you that the console is connected.

Console

Now, you are ready to resume the debugging. Click on "resume" which is available on the topmost taskbar. After that, you will see that your microcontroller is sending you the values from the analog device.

Result:

So, as we have completed everything, click on the resume button, and see the data inputs from your device. As you can see there are 512 data inputs per line. These data can be used for further interesting projects using NANOEDGE AI Studio (The next blog).

Result