FPGA, DSP & Embedded Hardware & PCB Design

Diesel Controller Display Board: 20×4 LCD Operator Panel

The operator panel of the diesel controller: a 20×4 LCD with a PIC18F452 that shows alarms, trips, battery voltage, charging current and pressure transmitter data; it completes the mainboard and the relay board.

Overview

This display board is the operator panel of the diesel controller, and it completes the two boards that came before it (the mainboard and the relay board). The mainboard and the relays control the system; this board is what the operator sees: a 20×4 character display that writes the state of the system on the screen. I built this board in 2021 and I also wrote its firmware, so that it works in step with the firmware of the diesel mainboard.

What it shows

The board writes the state of the diesel generator as text on the display, including:

the log and the value of the pressure transmitter,
alarms and trips,
the battery voltage,
the battery charging current,
and the other parameters of the system.

The diagram below shows the data path.

Main parts of the circuit

Processor: a PIC18F452 microcontroller in a 44-pin package, with a 20 MHz crystal.
Display: a 20×4 character LCD, model ACM2004F with an ST7066U controller, connected to the board through a 16-pin connector.
Communication: a MAX490 RS-485 transceiver with two termination resistors, to receive the data from the mainboard.
Power: an LM2676 step-down converter with an inductor, which brings the input voltage to the voltage the board needs.
Front panel: connectors for the front plate, which has the keys and the indicator LEDs.

Firmware

I wrote the microcontroller program of this board myself. The firmware receives the data that the mainboard sends and writes it on the display. I made it match the firmware of the mainboard, so the two boards work as one system.

PCB

The board is small and compact, and like the other boards in this set it was designed in Altium Designer. The connectors and mounting holes are placed so the board sits behind the front plate. The design is RoHS compliant. I blurred logos and company names in the images.

Result

The operator panel of the diesel controller, with hardware and firmware of my own: a display that gives the operator the alarms, the trips, the battery voltage, the charging current and the pressure data. Only the pictures and a general description are shown on this site.