16f88 asm question

MIOS programming (Assembler)
1

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

2

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

so this one is solved  :slight_smile:

only the wreg problem remains…

3

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.

4

I have modified the code to avoid the WREG stuff

only to find out that I can’t access my programmer until next week  :frowning:

In the meanwhile the program is running on a core :slight_smile:

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

5

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

6

Lol  :slight_smile: