December 2004, Issue 173

H8/38024F-Based Programmable Timer

CONSTRUCTION

Modifying the demo board was straightforward. I removed everything except the MCU, LCD, and serial port hardware. I was initially surprised to find out that the board came with a 5-VCC regulator, because the H8 is a 3.3 V-only part. But, it appeared that no permanent damage had been done. Even the standby current was still well within the specifications. The board was ready to go after I rerouted some LCD segments and power traces and added push buttons, a battery holder, voltage reference, and piezo.

Everything fit comfortably in a standard plastic box. I made the front panel legend with an adhesive Mylar laminating sheet (commonly available at office supply stores) that I ran through a laser printer.