PIC Geliştirme Kartı

Completed

My first board design: a PIC18F46K22 development board with an LCD, zero-cross detection and triac-based AC load control. Drawn in Proteus from schematic to PCB.

PIC18F46K22
Proteus
PCB Design
Triac
Optocoupler

My first board

3D view of the PIC development board: 40-pin PIC18F46K22 in the middle, power block and potentiometer on the left, optocouplers and triac on the right

This is the first electronic board I drew end to end, from schematic to PCB. I designed it in Proteus. The goal was to try a microcontroller's basic jobs, such as analog reading, a display, buttons and AC load control, on a single board.

What's on the board

Microcontroller: PIC18F46K22 with an external crystal oscillator
Power block: 5 V from a 9 V input through a 7805 regulator, with filter capacitors and a power LED
LCD: a 16×2 character display showing the ADC value and voltage read from a potentiometer (e.g. "ADC: 1022 · Voltage: 4.99")
Voltage adjuster: an RC-filtered potentiometer on an ADC input
User input: 3 buttons with pull-up resistors and debounce capacitors
Zero-cross detection: two PC817 optocouplers detect the positive and negative half-cycles of the AC sine separately
AC load control: a triac isolated by a MOC3021 opto-triac; together with zero-cross timing it allows phase-angle control (dimming)
Expansion: every port is broken out to pin headers

Schematic

The schematic is split into blocks: microcontroller, LCD, power, voltage adjuster, buttons, crystal and the AC control section.

PCB

Two-layer PCB layout of the PIC development board: blue and red traces around a 40-pin socket

The board is a two-layer design. The microcontroller sits in the middle, the power block on the left and the AC side (optocouplers and triac) in the top-right corner, keeping the high-voltage side away from the rest of the board.