X-Git-Url: https://git.gir.st/Chiptunes-pms150c.git/blobdiff_plain/29ec690644c48734d6732357e54d3dfbb82b07dd:/bsv.S..54babda0453493de38b5ff809f0a30c408fb8626:/bsv.asm

diff --git a/bsv.S b/bsv.asm
similarity index 80%
rename from bsv.S
rename to bsv.asm
index b3a6ee5..e83e3a4 100644
--- a/bsv.S
+++ b/bsv.asm
@@ -54,6 +54,13 @@ ihrcr = 0x0B
 calib_freq = 4096000 ; Hz
 calib_vdd  = 3000 ; mV
 
+; Clock Parameters:
+; during playback: IHRC/4, WDT off, keep ILRC on
+active_clock = (( 0<<5 | 1<<4 | 0<<3 | 1<<2 | 0<<1 | 0<<0 ))
+; during deep-sleep: ILRC/1, WDT off
+sleep_clock = (( 7<<5 | 1<<4 | 0<<3 | 1<<2 | 0<<1 | 0<<0 ))
+; for extra power saving, consider: 6<<5|0<<3 for ilrc/6, 2<<5|1<<3 for ilrc/16
+
 ; cycle count (worst-case)
 ; mod3:    28
 ; g:       81
@@ -191,10 +198,10 @@ g:
 	RET
 
 init:
-	; clock setup (no calibration):
+	; clock setup:
 	SET1	clkmd, #4	; enable IHRC
-	MOV	a, #(( 0<<5 | 1<<4 | 0<<3 | 1<<2 | 0<<1 | 0<<0 ))
-	MOV	clkmd, a	; switch to IHRC/4, WDT off; keep ILRC on
+	MOV	a, #active_clock
+	MOV	clkmd, a	; switch to IHRC
 
 	;; .org 0x46 ; comment out on 2nd iteration
 	; calibration placeholder:
@@ -215,10 +222,10 @@ init:
 	MOV	sp, a
 
 	; portA setup:
-	MOV	a, #0xff
-	MOV	pac, a		; data direction: all output
-	MOV	a, #0
-	MOV	padier, a	; disable pin wakeup
+	MOV	a, #0x50	; data direction: PWM & debug output, rest input
+	MOV	pac, a		; (conserves power, apparently)
+	MOV	a, #(( 1<<4 ))
+	MOV	padier, a	; disable pin wakeup, except on audio pin
 	MOV	pa, a		; PortA data = 0
 	MOV	paph, a		; disable all pull-ups
 
@@ -228,9 +235,8 @@ init:
         ; highest "carrier frequency" for the PCM samples we can generate is by
         ; setting Timer2 to 6 bit, (IHRC/1)/1 mode, giving a frequency of
         ; (4*4.096MHz)/2^6 = 256kHz.
-	MOV	a, #0x7f
-	MOV	pwm, a
-	MOV	tm2b, a		; pwm duty cycle 50%
+	MOV	pwm, a		; clear
+	MOV	tm2b, a		; clear
 	MOV	a, #(( 2<<4 | 3<<2 | 1<<1 | 0<<0 ))
 	MOV	tm2c, a		; timer2: IHRC, PA4, PWM, not inverted
 	MOV	a, #(( 0<<7 | 1<<5 | 0<<0 ))
@@ -282,7 +288,8 @@ init:
 	ENGINT
 
 loop:
-	;TODO: test i2==0x78 to enter halt()
+	MOV	a, i2
+	CEQSN	a, #0x78	; compare, skip next if equal
 	; Note: usually, this is the place where the MCU is put into some
 	; sort of low power/sleep mode. But the Padauk's stopexe instruction
 	; causes the ISR to a) run at greatly reduced frequency (100hz vs
@@ -292,9 +299,46 @@ loop:
 	; anyways).
 	GOTO	loop
 
+	; at this point, i2==0x78, i.e. the music is finished.
+	; => goto halt (fallthrough)
+halt:
+	DISGINT
+	CLEAR	i2		; clear halting signal
+
+	; Note: disabling the timers isn't strictly necessary (as stopsys halts
+	; all timers anyways), but I'm hoping it may reduce power consumption.
+	; We're lucky that we only need to toggle a single bit to switch
+	; between the required clock source and 'off' (0010xxxx->0000xxxx for
+	; timer2, 100xxxxx->000xxxxx for timer16), so we can hack our way out
+	; of loading an immediate each time.
+	SET0	tm2c, #5
+	SET0	t16m, #7
+
+	SET1	pa, #4		; assert a high level on the audio pin for good measure
+	SET0	pac, #4		; ... before setting it to input mode (optional)
+
+	;switch to ilrc clock
+	MOV	a, #sleep_clock
+	MOV	clkmd, a
+	SET0	clkmd, #4	; disable ihrc
+
+	STOPSYS
+	; (at this point, we wait for an i/o-toggle wake up event to resume execution)
+
+	MOV	a, #active_clock
+	MOV	clkmd, a	; switch to IHRC again
+
+	SET1	pac, #4		; restore output mode for audio pin
+
+	;reenable timer16, timer2
+	SET1	tm2c, #5
+	SET1	t16m, #7
+
+	ENGINT
+	GOTO	loop
+
 interrupt:
 	PUSH	af
-	SET1	pa, #3 ;debug2
 	T1SN	intrq, #2	; if intrq.t16 is triggered, skip next
 	GOTO	ivr_end
 
@@ -303,7 +347,7 @@ interrupt:
 
 	SET1	pa, #6		; debug
 
-	;TODO: send pwm data to timer2
+	; send pwm data to timer2:
 	MOV	a, pwm
 	ADD	a, #4
 	MOV	tm2b, a