Atmel STK511 User Manual page 29

STK511 Transmitter Board
KeepAlive:
; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; routine: ISRPinChg
; calls: Debounce, S1S2Pressed, WDTStart
; called by: <uC interrupt firmware>
; function: services a single button-press; and, checks for simultaneous
; button press (for changing modulation modes)
; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
ISRPinChg:
ISRPinBoth:
SETmodeASK:
5-6
4842B–AVR–10/09
RJMP Main
PUSH R19
IN r31, SREG
CLI
WDR
RCALL Debounce
IN r16, PINB
CPI R16,0x06
BREQ ISRPinBoth
CPI R16,0x02
BREQ ISRPinS2
CPI R16,0x04
BREQ ISRPinS1
RJMP ISRPinChgEnd; TP - Exit if glitch
CPI MODE,FSK
BREQ SETmodeASK
LDI mode,FSK
RJMP ISRPinLoop
; TP - All functions must have push and pop
statements!
; save Status Register
; TP - Disable interrupts
; TP - Clear watchdog timer
; TP - Add delay for debounce
; see which button was pushed
; TP - IF BOTH
; TP - IF only S2
; TP - IF only S1
; TP - For both buttons pressed, check current
state
; TP - If currently FSK, set mode to ASK
; TP - If not FSK, set mode to FSK
; TP - Exit button ISR when buttons released
STK511 User Guide