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willy

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Posts posted by willy

  1. Posted · Report reply

    Hi.

    I'am trying to understand HOW EXACTLY GPIO's in jaguar are working.

    Let's take first example, eeprom access code developed by Atari. Take look at the last section:

      

    JOY1		equ	$f14000		;this we'll use as our I/O base address
GPIO_0		equ	$f14800		;General purpose I/O #0
GPIO_1		equ	$f15000		;General purpose I/O #1
;
;   Equates derived from the above
;    to allow indirect with 16-bit displacement addressing
;
GPIO_0of	equ	GPIO_0-JOY1	;offset to GPIO_0 (when addr reg Ax -> JOY1) 
GPIO_1of	equ	GPIO_1-JOY1	;offset to GPIO_1 (when addr reg Ax -> JOY1) 
;
; entry:
;  a0 -> JOY1
;  d2.w = 9-bit command to write
;
out9bits:
	rol.w	#8,d2		;align 1st serial data bit (bit8) to bit0
	moveq	#8,d3		;send 9
out9lp:
	move.w	d2,GPIO_0of(a0)		;write next bit
	nop
	nop
	nop			;delay next write
	nop
	nop
	nop
	rol.w	#1,d2		;adjust bit0 for next datum
	dbra	d3,out9lp	;go for all 9 or all 16
	rts

     

    this line: 

    	move.w	d2,GPIO_0of(a0)		;write next bit

    asserts clock signal line (GPIO0) and set D0 data line.

    I'm wondering how the Clock signal is deasserted ?

     

    Another example form same code, asserting /CS line (GPIO1): 

    	tst.w	GPIO_1of(a0)	;strobe ChipSelect

    How it is deasserted ?

     

    Seems like I missed something??

    Hope somebody can help with understanding that.

     

    Best Regards

    Willy.

     

  3. Posted · Report reply

    Skunkboard production batch.

    Declare list.

     

    Hi.

     

    As I promissed on SillyVenture 2013, I will manufacture a batch of SkunkBoards.

    To start the batch, I need minimum 100 declarations of buy. (25 at This Moment)

     

    Price will be €65 (ca. $91 atm) + shipping, if you declare buy until deadline: 23.03.2014.

    And €75, if you will not declare and it will be something that was not sold.

    The price is including VAT, and all taxes in EU.

    If You live outside EU, Import duties may apply or something.

     

    The license will be Donationware: Do you like it? - Donate to the designers.

    http://www.harmlesslion.com/cgi-bin/showpr...arch=skunkboard

     

    This announce will be published on more places, so remember to put yourself only in one of them.

     

    Thanks.

     

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