R32V2020 Timers

Timer Unit

There are multiple timers in the Timer Unit.

• x3800 - Elapsed Time Counter (FPGA clocks)
• x3801 - Microsecond Counter
• x3802 - Millisecond Counter
• x3803 - CPU Cycle Counter

Sample Code

Microsecond Counter

;	
; delay_uS - delay for the number of uSecs
; pass mSec delay in r8
; Uses routine uses r9 (saved and restored)
;

delay_uS:
	push	r9
	push	PAR
	lix	PAR,0x3801	; address of the uSec counter
	lpl	r9		; read the peripheral counter into r9
	add	r8,r9,r8	; terminal counter to wait until is in r8
loop_delay_uS:
	lpl	r9		; check the elapsed time counter
	cmp	r8,r9
	blt	loop_delay_uS
	pull	PAR
	pull	r9
	pull	PC

Millisecond Counter

;
; delay_mS - delay for the number of mSecs passed in r8
; pass mSec delay in r8
; Uses routine uses r9
;

delay_mS:
	push	r9
	push	PAR
	lix	PAR,0x3802		; address of the mSec counter
	lpl	r9			; read the peripheral counter into r9
	add	r8,r9,r8		; terminal counter to wait until is in r8
loop_delay_mS:
	lpl	r9			; check the elapsed time counter
	cmp	r8,r9
	blt	loop_delay_mS
	pull	PAR
	pull	r9
	pull	PC

CPU Cycle Counter

;
; readCPUCycleCounter
; return CPU cycle counter in r8
; Useful function for counting the number of CPU cycles it take to do something
;

readCPUCycleCounter:
	push	PAR
	lix	PAR,0x3803		; address of the uSec counter
	lpl	r8			; read the peripheral counter into r8
	pull	PAR
	pull	PC

Elapsed Time Counter

;
; readElapsedTimeCounter
; return timer count in r8
;

readElapsedTimeCounter:
	push	PAR
	lix	PAR,0x3800	; address of the uSec counter
	lpl	r8		; read the peripheral counter into r8
	pull	PAR
	pull	PC