Title: Optimization Help for Ohmmeter with Modbus and OLED Display on 16 MHz Arduino
Hello Arduino Community,
I’m working on an Arduino project for a precision auto-ranging ohmmeter using a 16 MHz Arduino Pro Mini. The project involves measuring resistances from 0 Ohms to 1 GOhm, displaying the results on an OLED display, and handling Modbus master functionality.
The current code for the ohmmeter is functioning well, but I encounter performance issues when adding the Modbus library. The system becomes less responsive and struggles to keep up with both Modbus communication and OLED updates.
Project Requirements:
- Modbus master functionality
- OLED display updates (SSD1306)
Current Code Overview: The code uses FreeRTOS to manage tasks, including resistance measurement and display updates. However, the performance suffers due to the 16 MHz clock speed.
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Arduino_FreeRTOS.h>
#include <ModbusMaster.h>
// Constants
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1 // Reset pin #
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
ModbusMaster node;
void setup() {
Serial.begin(9600);
// Initialize OLED
if(!display.begin(SSD1306_I2C_ADDRESS, 0x3C)) {
Serial.println(F("SSD1306 allocation failed"));
for(;;);
}
display.display();
delay(2000);
display.clearDisplay();
// Initialize Modbus
node.begin(1, Serial); // 1 is the Modbus slave ID
node.preTransmission(preTransmission);
node.postTransmission(postTransmission);
// Create tasks
xTaskCreate(MeasureTask, "MeasureTask", 128, NULL, 1, NULL);
xTaskCreate(DisplayTask, "DisplayTask", 128, NULL, 2, NULL);
}
void loop() {
// FreeRTOS manages tasks; no code here
}
// Measure task function
void MeasureTask(void *pvParameters) {
for (;
{
// Measure resistance (pseudo-code)
// int resistance = readResistance();
// Send Modbus command (pseudo-code)
// node.writeSingleRegister(0x01, resistance);
vTaskDelay(pdMS_TO_TICKS(1000)); // Delay between measurements
}
}
// Display task function
void DisplayTask(void *pvParameters) {
for (; {
// Update OLED display (pseudo-code)
// display.clearDisplay();
// display.setCursor(0, 0);
// display.print("Resistance: ");
// display.print(resistance);
// display.display();
vTaskDelay(pdMS_TO_TICKS(500)); // Delay between display updates
}
}
void preTransmission() {
// Prepare for Modbus transmission (if needed)
}
void postTransmission() {
// Clean up after Modbus transmission (if needed)
}
Issues and Questions:
- The code becomes unresponsive when the Modbus library is added.
- Are there any optimizations or improvements I can make to handle both Modbus communication and OLED updates more efficiently on a 16 MHz Arduino?
I appreciate any guidance or suggestions you can provide to help optimize the code and improve performance.
