16f88 asm question

[mess]

Hi,

I'm working on a small 16f88 project in assembler

using the speakjet code as template...

*Can someone explain the use of SWITCHBANK_...?

I understand the banked system with pic18f... with BANKSEL variable

but I don't know when to switch banks with a 16f88

my variable declarations:

shared_ram		udata_shr
W_TMP			res	1
STATUS_TMP		res	1
FSR_TMP			res	1

gpr0			udata
NOISE			res 3
TMP1			res 1

...and the code without switches

IRQ_Handler_NoiseInt
	;; noise generator
	;; new bit = b18 exor b13
	;; shift NOISE one to the left, insert new bit as LSB
	; TMP1 = NOISE >> 2
	rrf		NOISE, W
	rrf		WREG, W
	movwf	TMP1
	; WREG = NOISE+1 >> 4
	rrf		(NOISE+1), W
	swapf	WREG, W
	; WREG = WREG exor TMP1
	xorwf	TMP1, W
	; carry = LSB of WREG
	rrf		WREG, W
	; three byte shift register
	rlf		(NOISE+2), f
	rlf		(NOISE+1), f
	rlf		NOISE, f

	; ouput new shift register value to RA2
        ; the output value is in the carry flag from last shift
	bc		IRQ_Handler_NoiseInt_Out_1
        bcf		PORTA, 2
	goto	IRQ_Handler_NoiseInt_End
IRQ_Handler_NoiseInt_Out_1
	bsf		PORTA, 2
IRQ_Handler_NoiseInt_End
	goto IRQ_End

*I also get a assembler error on WREG (symbol not defined)

does anybody knows how to solve this?

  Michaël

[mess]

the answer to the first question was on page 11 of the datasheet

so this one is solved  :)

only the wreg problem remains...

[stryd_one]

I'm not 100% sure how/why it works, but I know the 16F8* doesn't have a W register SFR. Hopefully someone can explain wtf that's all about, obviously the W register exists, but F&^ if I know why it can't be directly addressed....

In short you'll have to MOVWF your data to a variable and do the bitshift there.

[mess]

I have modified the code to avoid the WREG stuff

only to find out that I can't access my programmer until next week  :(

In the meanwhile the program is running on a core :-)

this was a lot of effort for a simple digital noise generator...

[stryd_one]

Yeh it's tough being a pioneer! But we love you for it  :-* ;D

[mess]

Lol  :)