Microchip PIC16F84A & MT8870 DTMF repeater controller

Description: This DTMF controller, based on the PIC16F84A microcontroller, is straightforward and cost-effective to construct. It provides practical experience in utilizing and programming PIC microcontrollers. The controller measures 10 cm x 6 cm and can be housed within a repeater project enclosure. It features eight open-collector (OC) outputs for driving up to eight relays. The outputs are accessible via a 12-pin header socket or a screw-in terminal block, allowing for ribbon cable connections. In addition to the eight OC outputs, the header or terminal socket also supplies 12V, ground, and 5V (for pull-up resistors only). The controller does not include relays and is designed to integrate into an existing project requiring DTMF control. It can drive 5V or 12V relays of any type without issues. The firmware for the PIC is available for download in an ASM file, secured with the password 1234, which can be changed during the programming of the PIC. This firmware has been tested, and the controller operated flawlessly without missing any commands.

The DTMF controller circuit utilizing the PIC16F84A microcontroller is designed to facilitate remote control applications through Dual-Tone Multi-Frequency (DTMF) signaling. The circuit's compact dimensions (10 cm x 6 cm) allow for easy integration into existing repeater projects, making it an efficient solution for users seeking to implement DTMF control without extensive modifications to their systems.

The core of the circuit is the PIC16F84A microcontroller, which processes incoming DTMF signals and generates corresponding control outputs. The microcontroller's firmware, written in assembly language, interprets the DTMF tones and activates the appropriate open-collector outputs. The eight OC outputs are capable of driving relays, enabling control of various devices or systems. Each output can be configured to either activate or deactivate a relay based on the received DTMF command.

Connectivity is facilitated through a 12-pin header socket and a screw-in terminal block, providing flexibility in wiring configurations. The inclusion of 12V and 5V power supplies at the header/terminal socket supports additional circuitry, such as pull-up resistors for signal stabilization. The design ensures that the controller can manage both 5V and 12V relays, accommodating a wide range of relay types and configurations.

The firmware for the PIC16F84A is crucial for the operation of the controller. It is available for download, allowing users to program the microcontroller with the necessary logic to interpret DTMF signals accurately. The use of a password-protected ASM file adds a layer of security, while also permitting customization of the firmware as needed.

In summary, this DTMF controller circuit represents a practical and efficient solution for implementing remote control functionalities in various electronic projects. Its simple design, combined with the versatility of the PIC16F84A microcontroller, provides users with a reliable tool for DTMF signal processing and relay control.This PIC16F84a based repeater (DTMF) controller is very simple & economical to build. It also gives you hand-on experience of using & programming PIC Micro controllers. Controller measures 10cm X 6 CM and may be housed in your repeater project enclosure Controller has 8 OC outputs to drive 8 relays. Outputs are available at 12pin header socket or screw-in terminal blocj where a ribbon cable may be connected. In addition to 8 OC outputs, header/terminal socket also provides 12V, Ground & 5V (for pull-ups only). Controller is without relays & is designed to be accommodated within an existing project, where DTMF control is required.

It will drive 5/12V relays of any type, without problems. Firmware for PIC is available here for download in. ASM file with password 1234 which may be changed at the time of programming the PIC. This firmware was tested & controller worked perfectly without missing any command.