s21 interrupt and Internet of Thing board


there are four interrupts: int0, int1, int2, int3
interrupt vector at M[1000-1003]
only one interrupt is accepted and it runs to completion.  ***
priority:  int0 > int1 > int2 > int3

instruction to support interrupt

int n          op x 31 23   software interrupt (not implemented yet)
reti            op x 31 24   return from interrupt

trap r1 #15     disable interrupt r1 = (0,1,2,3)
trap r1 #16     enable interrupt r1 = (0,1,2,3)
trap r1 #17     sleep and wait for interrupt

IoT board

timer0  ties to int0
timer1 ties to int1
when reset, only int0 is enable

stack pointer is r29
return value is r28

trap r1 #13     set timer0 range
trap r1 #14     set timer1 range

trap r1 #18     read port, r1 is port number
trap r1 #19     write port, r1 is port number

port

10   analog input (sine wave)
11   digital input (square wave)
12   random number input     
13   master clock input           the number of clock since the board reset


last update 28 Jan 2017