P80C552, EPROM, NOVRAM, RS-232, Piezo, Dot-Matrix LED Displays
This module was designed as an industrial timer used for dispensing 2-part foam. Originally for Foamtek PMC IPI as a Foam Dispensing Machine Timer. We built about 500 of these units, so the design is quite stable. There is a companion power supply module, but is not required as all you need is 5VDC.
The Philips 80C552 Processor is running at 16MHz via an external crystal. The 80C552 is a derivative of the 8031/8051 and executes it's code from an external socketed EPROM (27C256). There is limited amounts of on-chip RAM, so programming can be a bit tricky, especially in C. A good C compiler can really help with this. We wrote all the code in BSO/Tasking C51, and still made it into 256 bytes of RAM.
Since the '552 Processor is not capable of on-chip emulation, an external emulator or debugger can be worth it's weight in gold! Since these tools can be quite expensive, we supply a working application that you can use to start from. The application supplied is the actual timer code we shipped with all those units.
A 10pin header connects a keypad to the timer module, and is setup as a 5x4 key matrix. We also sell the actual keypads since we ended-up with some leftovers. All other ports are presented on the four 6pin Molex headers. An LM34DZ is also built in for your temperature measurements.
The main attraction to this baby is the 6 digit 5x7 dot-matrix LED display. Shown here with a seemingly lack-luster MM:SS.T (timer) display. However, notice that each and every digit does not land on one of the six 5x7 display! This thing will scroll on a pixel boundary any ASCII text message you can feed it. The supplied timer application demonstrates this. When you power-up the timer, it will scroll text welcome messages, and also help messages. You can create ANY text string and display/scroll it on the LED's. The key to not using ALL the RAM, remember it's limited, is to use ROM Strings. A good C Compiler will let you specify what memory segment to stick constants in. For the BSO/Tasking Compiler, you specified as a ROM String, then it would stick all the text in the EPROM. The sample code looks into the desired ROM String, and using an offset, will scroll the message and only using a wee-bit of stack space while in the display scan routine.
This module is supplied assembled, which is completely through-hole, no surface mount. If you have the desire to assemble this boards, we can supply a bare PCB, or even a parts kit. Please contact us for details.
Board Dimensions: 3.15" X 6.30"
Full Schematics are supplied, with sample code written using the BSO/Tasking C Compiler.
We also have the matching Power Supply Unit.
It's not required, but matches quite nicely..
80C552 Timer Power Supply Module