December
2004, Issue 173
H8/38024F-Based
Programmable Timer
TIMER
SOLUTION
I
call my design the Programmable Yoga Timer (see Photo
1). The hardware is built around a modified Renesas
H8/38024F demo board from Basic Micro, which contains
the MCU, a four-digit LCD, an RS-232 serial interface,
and a power regulator. All the board needed was a healthy
diet to remove everything I didn’t need.
|
(Click
here to enlarge)
|
Photo
1—Take a look at the timer. To simplify the user
interface, most of the buttons have only one function
assigned to them. |
I
used the demo board because it already included most
of what I needed. This way I didn’t have to hand-solder
the MCU’s fine-pitch leads to a different board. Figure
1 shows the block diagram of the system.
|
(Click
here to enlarge)
|
Figure
1—The design is straightforward. A 3-V coin cell
provides plenty of power, because the H8/38024F
normally runs off the 32-kHz oscillator when it
isn’t asleep. The optional serial port allows for
in-system programming. |
