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>>> new 8048 variants and the microcontroller family’s weaknesses Like, for example, only one external interrupt and one timer, which was 8-bit. I did some re
by injb 3y ago
>>> new 8048 variants and the microcontroller family’s weaknesses
Like, for example, only one external interrupt and one timer, which was 8-bit.
I did some reverse engineering on an 80s Porsche engine management computer[1] that used the 8048. The engineers had to get really clever to work with these 2 issues. They used the reset pin as a second pseudo ext interrupt, which works ok but has a few side effects you have to deal with.
The lack of a 16 bit timer was single-handedly responsible for adding massive complexity all over the code. Basically the loops had to be capable of scaling themselves for engine speeds below a certain threshold because otherwise the timer would overflow!
You have to wonder if it was worth what they saved vs just using an 8051, especially considering that this car had 2 engine management computers, and the main one used an 8051!
[1] https://jhnbyrn.github.io/951-KLR-PAGES/ https://jhnbyrn.github.io/951-KLR-PAGES/
- kjs3 3y agoYou have to wonder if it was worth what they saved vs just using an 8051 There are all sorts of direct and indirect costs in something like this. Did they perhaps reuse an older design? I've run into all sorts of weird/obsolescent bits in manufacturing environments (like industrial controllers) where the answer was "yeah...newer tech would be nice, but we already had this design on the shelf and it fit the minimum need and the NRE costs were covered and it's been debugged within an inch of it's life and the regulatory hurdles have been cleared and the manufacturing/supply chain kinks have long since been worked out and our customer support people are up to speed, soooo...". Cool RE job @injb, BTW.