Nice to hear you again. Since I want to extend interrupt sources and only want use one 8051, but the 8259 is one of my choices. Do you have any suggestions? Best regards.
I'd like to know what is the reason to stay away from 82xx chips. OK, here are a few I can think of right off the bat, I am sure there are more, but the "no more 82xx" happened ten or more years ago, so my memory may be a bit rusty. Anyhow, the deciding factor whatever it was - was an absolute. *They are designed for the x86 and thus the interface is bad for a '51 *They are, in may cases, too slow for a modern '51 derivative to drive as MMIO *The only place you can buy them is an antique store *They ususally require external logic to be interfaced to a '51 *Everything we used a 82xx for, in the olden days, can now be done better, cheaper, and safer using other means. Erik
Since I want to extend interrupt sources and only want use one 8051 An interrupt expander, whatever the type, is usually a bad choice (in a '51 environment). where can you get more interrupts? * every timer can be made an external interrupt. * every comparator, with interrupt associated, can be used as a logical interrupt. * A PCA can give you 5 additional external interrupts. * and A/D with limit interrupts, can be used as a locical interrupt. So, whith something like a SILabs F12x you can have about 15 external interrupts. an example of converting an interrupt to "external": configure a timer as a counter, load it with ffff and the very first clock on the input pin gives an interrupt. Erik