posted by Ol'zeke

I was really intrigued by the NXP LPC800-DIP product. The fact that it came in an 8051 40pin DIP formfactor (FF) got me hooked. I had purchased two 8051 dev boards and acquired 3 OEM boards through out the years. The 8051 is/was a workhorse. I noticed some (PS2)keyboard to ascii products that use a smaller version [pin count] of the 8051.

My OEM 8051 pcbs had a 14pin display connector, a 6x3 matrix keypad, a relay, and several other discrete I/Os on it. I have wanted to use them for over 20 years !!! Now that I am semi-retired – I have time to develop them into a particular project. The 8051 FF was the final straw to motivate me.

I have written up 2 forum posts with information on their IO-abilities. I submitted some ARMbasic routines to access the standard address and data lines in the “LPC800-DIP” post; that includes a ‘Peek & a Poke’. My donated software routines are here ::LPC800-DIP

Now the sad part….something is feeding the ‘data bus’ and interfering with my matrix keypad decoding. My basic troubleshooting hasn’t been able to identify the culprit. My logic analyzer is still a project down the road. Perhaps I didn’t reverse engineer the pcb well enough…. I did get this far - - oh the case is now painted a warship gray:: see this forum post LPC800-DIP-8051

So ... The future

–-- yes I want the project to happen – (my XMAS tree GTD display). I have two pcbs leftover from my Dicer-delux project that should be useable. They use the newer ARMStamp (by Coridium). I was forward thinking and included a 4x4 matrix keypad and 4-bit LCD connections.!! [I don’t like to waste my IO pins by not assigning them to something]

The wrap – the LPC800-DIP is a good product – has a goodly amount of IO presented on the 8051 FF. There are several duplicated pins though and one pin that can only have 3.3vdc as an input. With the learning to create “ an address/data bus”, a careful design could be implemented for some of the older ICs that are ‘bus’ orientated. (I have one or two 8x8 matrix keyboards that I could turn into a possible ASCII-serial terminal. Some of the ‘matrix’ pins could be used to feed the LCD) Some OEM boards could be retro-fitted as long as they didn’t use a lot of the Port1 pins- as some are needed for the address latching. The timing of the processor (runs about 2+ times faster and doesn’t use so many clock cycles per instruction) could be an issue, though that could be downsized. ........ Enjoy the experience - this is all fun ! Olzeke

Schematic

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