OK, I'm a novice with the 8051. How do you map a port pin to an external interrupt (or visa versa, say External interrupt 2)? I'm assuming that there are no dedicated pins for each of the seven Ex. interrupts on my chip and they have to be assigned somehow to a pin/bit on a specific port. Is this assumption correct? -Michael
7 external interrupts on an 8051? Wow, which part (Vendor and ID) are you using. The most I've seen is three. Anyhow, they are hardwired on the standard 8051's. If you want your A/D to signal end-of-convert on /int0 then connect it to /int0 and install your LJMP + A/D ISR address (little endian of course) at the /int0 interrupt vector location. From Intel's MCS-51 User's Manual:
Vector Vector Address RESET 0000H IEO OO03H <-- External Intr 0 TFO OOOBH IE1 O013H TF1 OOIBH RI & TI O023H TF2 & EXF2 O02BH
Hi Mark, Thanks for the info. The 8051 I'm using is actually embedded in a Cypress USB chip (CY7C646xx, aka EZ-USB FX). It has 7 external interrupts (one dedicated to USB another dedicated to I2C) and three timers. The part is cheap in quantities, I don't know about singles. The info I was looking for WAS hidden in the tech reference but I had to bounce all over the book to find it.
"7 external interrupts on an 8051? Wow, which part (Vendor and ID) are you using." You could do it with a Triscend E5. http://www.triscend.com/products/e5.htm