Prototype logic board with PIC24 micro and I/O

Custom Logic Board

By admin, March 22, 2015

Microcontroller logic board with I/O prototyped in short order


For several weeks I was quite busy on a contract job creating a custom logic board for a small manufacturer out west. I had estimated 5-6 weeks (about 150 hours), not including time to acquire PC boards and build first articles. At 56 hours billed I had the very legitimate breadboard shown and a large portion of the firmware prototyped. The client felt that wasn’t sufficient progress, so I ended that relationship and refunded his payments in full.

If anyone needs a nice little custom logic board and firmware, let me know!

So far it includes:

  • PIC24HJ microcontroller with on-board Flash, programmed in C
  • 16 bit Sigma Delta ADC (can be up to 22 bit) for RTD, thermocouple, low level analog input
  • Quadrature encoder inputs (up to 3) plus momentary buttons and audible alarm/clicker
  • Multiple PWM outputs for control of solid state relays (for heater loads) and PWM fans
  • Full H-bridge driver for brushed DC motor direction/speed control
  • Serial-interfaced 7-segment or dot-matrix LED displays (via SPI) with many options
  • FRAM non-volatile memory for configuration and error logging

I also just added an I2C interface to a multi-line LCD. That’s primarily for use during development (it only takes 2 processor pins!) but could hang around in a product.


Here my breadboard is connected to a recent addition to my tools: a Hewlett-Packard 54540A DSO. Read the tale of that scope.