How to check if the microcontroller is started?

To check if a microcontroller has started successfully, you can use several methods, depending on the available resources and desired level of confirmation. Here are some common approaches:

1. Use an LED Indicator
A simple and effective method to confirm that a microcontroller has started is by toggling an LED at the beginning of the program.

Implementation:

1. Connect an LED to a GPIO pin with a current-limiting resistor.
2. In the startup code (usually in the main() function or equivalent), toggle the LED.
3. Use a delay to make the toggling visible (e.g., blink the LED).

Code Example (Pseudo-C):

c

#include <microcontroller.h>  // Replace with your microcontroller's header file

void main() {
    GPIO_Init(LED_PIN, OUTPUT);  // Initialize LED pin
    while (1) {
        GPIO_Write(LED_PIN, HIGH);  // Turn on LED
        Delay(500);                // 500ms delay
        GPIO_Write(LED_PIN, LOW);   // Turn off LED
        Delay(500);                // 500ms delay
    }
}

2. Serial Communication Output
If your microcontroller has a UART interface, you can send a debug message over serial to confirm the system has started.

Implementation:

1. Initialize the UART peripheral.
2. Send a startup message as the first step in the program.

Code Example (Pseudo-C):

c

#include <uart.h>  // Replace with your microcontroller's UART header file

void main() {
    UART_Init(9600);                     // Initialize UART with baud rate 9600
    UART_SendString("Microcontroller Started\n");
    while (1) {
        // Main loop
    }
}

Monitoring:
Use a terminal application (e.g., PuTTY, Tera Term, or Arduino Serial Monitor) on your computer to see the message.

3. Debugging with a JTAG/SWD Interface
If your microcontroller supports JTAG or SWD debugging, you can use a debugger to check if the system has started.

Steps:

1. Connect the debugger (e.g., ST-Link, J-Link) to your microcontroller.
2. Open your IDE or debugging tool (e.g., Keil, STM32CubeIDE).
3. Place a breakpoint at the start of the main program or initialization code.
4. Step through the code to verify that the microcontroller has started.

4. Use a GPIO Pin Output
Set a GPIO pin to a known state during initialization and monitor its output with a multimeter, logic analyzer, or oscilloscope.

Implementation:

1. Set a GPIO pin to HIGH or LOW at the start of the program.
2. Check the voltage at the pin to verify the state.

Code Example (Pseudo-C):

c

void main() {
    GPIO_Init(TEST_PIN, OUTPUT);  // Initialize test pin
    GPIO_Write(TEST_PIN, HIGH);  // Set pin HIGH
    while (1) {
        // Main loop
    }
}

5. Measure Power Consumption
When the microcontroller starts running, it draws more power compared to an idle or reset state. Use a current meter to monitor the power supply.

Steps:

1. Insert a current meter in series with the microcontroller's power supply.
2. Observe the change in current when the microcontroller starts running.

6. External Watchdog or Reset Source
If an external watchdog timer or reset source is configured, it will reset the microcontroller periodically if it doesn't receive a signal. Check the output to verify that the microcontroller is periodically running.

7. Check Oscillator/Clock Signal
A running microcontroller will have an active clock signal on its oscillator pins. Use an oscilloscope to check the clock signal.

Steps:

1. Probe the oscillator or clock input/output pins.
2. Verify the expected frequency.

8. Read Status Registers
Some microcontrollers provide startup status in their system or power control registers.

Example:
For STM32 microcontrollers, you can check the System Control Block (SCB) or RCC_CSR registers for information about startup.
Code Example (STM32 HAL):

c

if (__HAL_RCC_GET_FLAG(RCC_FLAG_SFTRST)) {
    // The system was reset by a software reset
}

9. Bootloader or Startup Firmware
If you have a bootloader, it can send a "startup completed" signal over a communication interface (e.g., UART, CAN, or I2C).

Best Practices

• Combine methods for redundancy (e.g., use an LED indicator and serial message).
• Use hardware and software debugging tools for advanced monitoring.
• Always ensure a clear distinction between power-on and fully operational states for the microcontroller.

By implementing one or more of these methods, you can reliably confirm that a microcontroller has started.