Motorola DSP56000 Macro Cross Assembler  Version 2.03  89-08-04  15:58:57  loopevb.asm  Page 1



1      
2                        ;************************************************************
3                        ; file:loopevb.asm                                          *
4                        ;                                                           *
5                        ; Simple read ADC write DAC loop...                         *
6                        ; reads DSP56ADC16 data and writes to PCM-56                  *
7                        ;                                                           *
8                        ;************************************************************
9                        ; Written by Charlie Thompson 10/19/88 -- Rev 1.0 11/1/88
10     
11                                 opt     nomd,nocex,nocm,nomex
12     
13                                 page    132
14     
15                       ; Program start address
16     
17        P:0040                   org     p:$40
18     
19                       ; Set up ADS board in case of force break instead of force reset
20     
21        P:0040 08F4BE            movep             #0,x:$FFFE              ;set bcr to zero
                 000000
22        P:0042 0500BB            movec             #0,sp                   ;init stack pointer
23        P:0043 0500B9            movec             #0,sr                   ;clear loop flag
24     
25                       ; Set up the SSI for operation with the DSP56ADC16EVB
26                       ; The following code sets port C to function as SCI/SSI
27     
28        P:0044 280000            move              #$0,a0                  ;zero PCC to cycle it
29        P:0045 08C821            movep             a0,x:$FFE1
30     
31        P:0046 50F400            move              #$0001ff,a0
                 0001FF
32        P:0048 08C821            movep             a0,x:$FFE1              ;write PCC
33     
34                       ; The following code sets the SSI CRA and CRB control registers for external
35                       ; continuous clock, synchronous, normal mode.
36     
37        P:0049 50F400            move              #$004000,a0             ;CRA pattern for word length=16 bits
                 004000
38        P:004B 08C82C            movep             a0,x:$FFEC
39     
40        P:004C 50F400            move              #$003200,a0             ;CRB pattern for continous ck,sych,normal mode
                 003200
41        P:004E 08C82D            movep             a0,x:$FFED              ;word long frame sync: FSL=0;ext ck/fs 
42     
43     
44     
45                       ;************************************************************************
46                       ; Actual read A/D and write D/A -- insert application code as indicated *
47                       ;************************************************************************
48     
49                       ; The following code polls the RDF flag in the SSI-SR and waits for RDF=1
50                       ; and then reads the RX register to retrieve the data from the A/D converter.
51                       ; Sample rate is controlled by DSP56ADC16 board.   
52     
53     
54     
55     
56        P:004F 0AAE87  poll      jclr    #7,x:$FFEE,poll                   ;loop until RDF bit = 1
                 00004F
57        P:0051 084E2F            movep             x:$FFEF,a               ;get A/D converter data
Motorola DSP56000 Macro Cross Assembler  Version 2.03  89-08-04  15:58:57  loopevb.asm  Page 2



58     
59     
60                       ; Write DSP56ADC16 A/D converter data to the PCM-56
61     
62        P:0052 567000            move              a,x:$FFEF               ;write the PCM-56 D/A via SSI xmt reg.
                 00FFEF
63        P:0054 0C004F            jmp     poll                              ;loop indefinitely
64     
65                                 end
0    Errors
0    Warnings