Texas Instruments MSP430x4xx - Manual (Page 484)

Scan IF Operation
24-24 Scan IF
Simplest State Machine
Figure 24−12 shows the simplest state machine that can be realized with the
PSM. The following code shows the corresponding state table and the PSM
initialization.
Figure 24−12. Simplest PSM State Diagram
S1=1 & S2=0
S1=0 & S2=0
S1=1 & S2=1
S1=0 & S2=0
S1=0 & S2=1
S1=1 & S2=1
S1=1 & S2=0
S1=1 & S2=1
S1=0 & S2=1
S1=0 & S2=0
State 00
00000000
State 10
00000000
State 11
00000010
State 01
00000000
S1=0 & S2=0
S1=0 & S2=1
S1=1 & S2=0
S1=1 & S2=1
S1=1 & S2=0
S1=0 & S2=1
; Simplest State Machine Example
SIMPLEST_PSM db 000h ; State 00 (State Table Index 0)
db 000h ; State 01 (State Table Index 1)
db 000h ; State 10 (State Table Index: 2)
db 002h ; State 11 (State Table Index: 3)
PSM_INIT
MOV #SIMPLEST_PSM,&SIFPSMV ; Init PSM vector
MOV #SIFS20,&SIFCTL3 ; S1/S2 source
MOV #SIFCNT1ENP+SIFCNT1ENM,&SIFCTL4
; Q7 and Q6 disabled for next state calc.
; Increment and decrement of SIFCNT1 enabled