Path: utzoo!attcan!uunet!ginosko!sol.ctr.columbia.edu!cica!tut.cis.ohio-state.edu!husc6!rutgers!orstcs!boone@oce.orst.edu
From: boone@oce.orst.edu (Jeff Boone)
Newsgroups: comp.sys.next
Subject: YADSPQ (Yet Another DSP Question)
Message-ID: <11494@orstcs.CS.ORST.EDU>
Date: 5 Jul 89 07:40:32 GMT
Sender: usenet@orstcs.CS.ORST.EDU
Reply-To: boone@oce.orst.edu (Jeff Boone)
Organization: College of Oceanography, Oregon State Univ., Corvallis, Or.
Lines: 73


  I have been struggling with the DSP for the past week or so, and thought
I should tap into the net knowledge before I pull out the rest of my hair.

  Below is the assembly code that <should> return the 256 sine entries in
the internal Y memory ROM.  I used the initialization posted by Eric Thayer
to configure the DSP (although I don't use external memory, I still need
to enable the ROM data).  The rest of the code just marches through the 
sine table and sends the entries to the host.

  What actually comes out is the first 128 entries in the table, some
garbage, and then part of the table started over from the first.  And
to top it all off, it takes about 4 or 5 seconds to send this to the
host.  JEEZ I might as well use my calculator!  What gives?

  Would some kind soul please shine the light on me. :-)

------------------------------  DSP Assembly code  -----------------------


reset   equ     $0000			; Address of reset vector
start   equ     $40			; Start of program mem
data    equ     $100			; Start of ROM sine table in Y mem

	org	p:reset
	jmp	>init
	dup	$40-2
	nop
	endm
	
	org	p:start
init    movec   #6,omr			; Data rom enabled, mode 2
	bset    #0,x:m_pbc		; Host port
	movep   #>$0001F7,x:m_pcc	; Both serial ports (SC0 not available)
	bset	#3,x:m_pcddr		;    pc3 is an output with value
	bclr	#3,x:m_pcd		;    zero to enable the external ram
        movep   #>$004000,x:m_cra	; Set up for external clock on DSP port
        movep   #>$002300,x:m_crb	; Read L/~R on IF1
	movep   #>$000000,x:m_bcr	; No wait states on the external sram
        movep   #>$00B400,x:m_ipr  	; Intr levels: SSI=2, SCI=1, HOST=0

	move	#data,R2		; Point R2 to the ROM sine table
	nop				; Allow R2 time to update	
	move	y:(R2)+,A0		; Load first sine table value

	do	#256,end_out		; Send 256 sine values to host
xmt_dat	jclr	#1,x:$FFE9,xmt_dat	; Wait for host
	move	A0,x:$FFEB		; Send sample to host
	move	y:(R2)+,A0		; Update A0 with next sine value
end_out
		
	end	$40
	

------------------  Program to read the sine table  ----------------

	
#include <dsp/dsp.h>
#include <stdio.h>

main()
{
  int count;
  int output[256];

  DSPBootFile("sine.dsp");        // Load the dsp image file
 
  DSPGetRXArray(output,256);      // Get the 256 sine values from DSP
    
  for (count=0; count<256; count++)   // Print the values
     printf("0x%X\n",output[count]);
  
}