Design of a dual-microcontroller scheme to overcome the freeze problem for a smart data logger

Screen freeze (or no response) is a condition that often occurs in a Personal Computer (PC). In this condition, the PC has lost the ability to respond to its application programs. The same thing can also happen to a data logger, which is usually constructed by using a microcontroller or embedded processor. We propose a design of a dual microcontroller to overcome hang, or no response, of the main microcontroller in a data logger. One of the smart features is an auto restart or reboot, so the data logger with the `no response' condition is able to reboot without operator assistance. We used an ATmega128 as the main or master microcontroller and an ATtiny13 as the watchdog or slave microcontroller. The watchdog microcontroller detects the activity of the main microcontroller by monitoring a periodic signal from the main microcontroller. If a disruption occurs in the system and the main microcontroller is not able to send this periodic signal, the watchdog microcontroller would determine that a system failure has occurred. System failure will trigger the watchdog microcontroller to activate a relay to reset the main microcontroller. This capability is expected to increase the stability of the data logger and minimize the measurement data lost.