Realtime clock board for Z80/Z180
Time is money so why not add a battery backed realtime clock to your z80 system? I thought this was a good idea and designed a realtime clock and parallell I/O board for my generic Z80180 CPU board. It has a Dallas DS1302 RTC chip with its 32768 Hz chrystal, a lithium battery socket, some 74xx latches and tristate drivers and a PAL16V8 address decoder.
The J4 connector is a general purpose 4 bit output latch.
The J2 connector was designed to interface my old LCD/keyboard mini terminal. This device is described in the "Z80/Z180 hardware" section. Although J2 may also be used as a general purpose 8-bit bi-directional I/O port.
The RTC board has no jumpers to configure, address decoding is defined by the PAL-circuit. Please read the PAL source code (rtc.pds in rtc_pcb.zip file) for detailed information about the address decoding.
Click here to view the circuit schematic.
I have assembled and tested one RTC board and both the mini terminal and the realtime clock works fine.
Download rtc2_pcb.zip which contains the schematic and PCB layout files in Adobe Acrobat (.pdf) format. It also contains PALASM source and JEDEC file for the AMD PALCE16V8Q-15 decoder chip used.
Download rtc2_driver.zip which contains
source code for my realtime clock test program. Take a look at the main
program "rtc180.tml" first.
The program runs on OS-X 2.0 on my Z180 computer.
For more information, questions, feedback etc please contact me at:
francis.gormarker@swipnet.se
Last updated: January 4 2004