How do you know if a microcontroller is working or dead?

To determine if a microcontroller is damaged, here are some steps and "tricks" to check its functionality: 1. Check for Oscillation (Clock Signal): If the microcontroller uses an external crystal oscillator, verify that the clock signal is running. A damaged microcontroller might not oscillate, which can render it inoperable. Use an oscilloscope or logic analyzer to probe the oscillator pins (XTAL1 and XTAL2) or a clock-out pin, if available. 2. Inspect Physical Damage: Look for physical signs of damage, such as: Burn marks. Cracked packaging. Discoloration. Bent or broken pins. 3. Measure Power Supply: Ensure the microcontroller receives the correct power supply voltage at its VDD/VSS pins. If the microcontroller is damaged, it may draw excessive current or fail to power up. 4. Test the Reset Pin: Check if the reset pin behaves correctly: It should have a defined logic level (usually high or low, depending on the design). When toggled, it should cause a reset if the microcontroller is functioning. 5. Check for Program Execution: Flash a simple program, like toggling an LED or outputting a signal on a GPIO pin. Observe whether it executes as expected. 6. Probe GPIO Pins: Set a known output state (high or low) on a GPIO pin and measure it with a multimeter or logic analyzer. A faulty microcontroller may show incorrect or floating outputs. 7. Communication Test: Test any communication protocols (e.g., UART, SPI, I2C): Send commands and observe if the microcontroller responds. Check for data consistency. 8. Debug Interface Check: Use a debugger or programming tool to connect to the microcontroller. If the tool fails to detect it, the microcontroller might be damaged. 9. Temperature Check: After powering the microcontroller, touch the IC lightly to check for excessive heat. Overheating is often a sign of internal damage. Notes: Oscillation Alone is Not Enough: While oscillation is a good sign, it doesn't guarantee the microcontroller is fully operational. Internal logic, memory, or I/O may still be damaged. Perform tests systematically to isolate the issue, as some failures can be due to external factors like power supply or connections rather than the microcontroller itself.

1. Check for physical damage 2. Verify soldering

To thoroughly test each MCU, I’d use a test board with an adapter or socket for easy IC swapping. Each IO pin connects to an LED, running simple firmware for sequential testing. Communication and additional features can also be verified. For basic checks, confirming MCU-programmer communication suffices. Using a breakout board and tools like the Pocket AVR Programmer, I’d test each MCU swiftly via command line.

If it was programmed before and now is not doing its job, it may be dead or just its program is corrupt or being cleared. You may check the osc pin to see if the clock is there to make sure it is not dead. But to make sure 100%, you need to run a test program on it