F84 Miniature Real-Time Controller

Description: The F84 MRTC was my second design of a miniature real-time controller. This version uses PIC16F84 running with a low power X-tal 32,768Hz. The scheduler for 6-channel output was saved in EEPROM. No terminal for serial downloading of the scheduler. It`s suitable for fixed scheduler job. Two AA size battery provides +3V backup for clock operation when main power has failed. Time setting at 19:00 is set only once by pressing S1 button. The 6-channel open collector output provides max. 30mA @30V load.

The F84 MRTC is a compact real-time controller designed for specific scheduling tasks. The core of the device is the PIC16F84 microcontroller, which operates at low power and is clocked by a 32.768 kHz crystal oscillator. This frequency is commonly used in real-time applications, particularly for timekeeping, as it is derived from the standard frequency of quartz crystals used in wristwatches.

The system architecture includes an EEPROM where the scheduling information for the six output channels is stored. This allows the device to retain its configuration even when power is removed. The absence of a terminal for serial downloading indicates that the scheduling data is likely programmed directly into the EEPROM during manufacturing or initial setup, making it suitable for applications where the schedule is fixed and does not require frequent updates.

Power management is efficiently handled by utilizing two AA batteries, which provide a nominal voltage of +3V. This battery backup is crucial for maintaining clock operation during power outages, ensuring that the device remains functional and accurate. The implementation of a single button, S1, for setting the time to 19:00 simplifies user interaction, allowing for a straightforward setup process.

The output stage of the F84 MRTC features six open collector outputs, capable of sourcing a maximum current of 30 mA at a voltage of up to 30V. This configuration allows the controller to interface with various loads, making it versatile for different applications, such as controlling relays or driving other electronic devices. The open collector design also provides flexibility in connecting multiple outputs to a common line without interference, which is advantageous in certain control scenarios.

Overall, the F84 MRTC represents a robust solution for fixed scheduling tasks, combining low power consumption with reliable performance and ease of use.The F84 MRTC was my second design of a miniature real-time controller. This version uses PIC16F84 running with a low power X-tal 32,768Hz. The scheduler for 6-channel output was saved in EEPROM. No terminal for serial downloading of the scheduler. It`s suitable for fixed scheduler job. Two AA size battery provides +3V backup for clock operation when main power has failed. Time setting at 19:00 is set only once by pressing S1 button. The 6-channel open collector output provides max. 30mA @30V load.