📄 dmatimer.lst
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DMATIMER PAGE 1
1 ;********************************************************************
2 ;
3 ; Author : ADI - apps www.analog.com/MicroConverter
4 ;
5 ; Date : 7 September 1999
6 ;
7 ; File : DMAtimer.asm
8 ;
9 ; Description : performs Timer2 triggered DMA conversions on a
10 ; single ADC channel at 10KSPS (assuming 11.0592MHz
11 ; Mclk). Debugger or emulator must be used to view
12 ; results.
13 ;
14 ;********************************************************************
15
16 $MOD812 ; use 8052&ADuC812 predefined symbols
17
0040 18 DMACOUNT EQU 64 ; number of AD readings to take
0010 19 DMAINIT EQU 10h ; top nibble of DMAINIT = ADC channel
20
21 ;____________________________________________________________________
22 ; DEFINE VARIABLES IN INTERNAL RAM
---- 23 DSEG
0060 24 ORG 0060h
0060 25 DMASTOPH: DS 1 ; DMA stop address hi byte
0061 26 DMASTOPL: DS 1 ; DMA stop address lo byte
27
28 ;____________________________________________________________________
29 ; DEFINE SEGMENT OF EXTERNAL RAM
---- 30 XSEG
0000 31 ORG 000000h
0000 32 DMASTART: DS DMACOUNT*2 ; location for DMA results
0080 33 DMASTOP: DS 4 ; location for DMA stop sequence
34
35 ;____________________________________________________________________
36 ; BEGINNING OF CODE
---- 37 CSEG
0000 38 ORG 0000h
0000 02004B 39 JMP MAIN ; jump to main program
40
41 ;____________________________________________________________________
42 ; INTERRUPT VECTOR SPACE
0033 43 ORG 0033h ; (ADC ISR)
0033 C2CA 44 CLR TR2 ; stop Timer2
0035 C3 45 CLR C ; clear C to indicate DMA done
0036 32 46 RETI
47
48 ;====================================================================
49 ; MAIN PROGRAM
004B 50 ORG 004Bh
004B 51 MAIN:
52
53 ; PRECONFIGURE external RAM for DMA capture on a single channel...
004B 75EF00 54 MOV ADCCON1,#00h
004E 900080 55 MOV DPTR,#DMASTOP ; store DMASTOP 16bit value..
0051 858261 56 MOV DMASTOPL,DPL ; ..as a high byte & low byte
0054 858360 57 MOV DMASTOPH,DPH ; (for use in GETSTOPFLAG subr)
0057 900000 58 MOV DPTR,#DMASTART ; set DPTR to DMASTART address
DMATIMER PAGE 2
005A 7410 59 SETUP: MOV A,#DMAINIT ; set up x-mem with init value
005C F0 60 MOVX @DPTR,A
005D A3 61 INC DPTR
005E E4 62 CLR A ; clear second byte
005F F0 63 MOVX @DPTR,A
0060 A3 64 INC DPTR
0061 120097 65 CALL GETSTOPFLAG ; C cleared if DPTR>=DMAEND
0064 40F4 66 JC SETUP
67
0066 7410 68 MOV A,#DMAINIT ; "dummy" DMA location..
0068 F0 69 MOVX @DPTR,A ; ..to preceed stop command
0069 A3 70 INC DPTR
006A E4 71 CLR A
006B F0 72 MOVX @DPTR,A
006C A3 73 INC DPTR
74
006D 74F0 75 MOV A,#0F0h ; DMA stop command
006F F0 76 MOVX @DPTR,A
77
78 ; CONFIGURE ADC and Timer2 for DMA conversion...
79
0070 75D200 80 MOV DMAL,#0 ; Timer2 DMA must start from 0
0073 75D300 81 MOV DMAH,#0 ; (must write DMA registers in this
0076 75D400 82 MOV DMAP,#0 ; order: DMAL, DMAH, DMAP)
83
0079 75CAD2 84 MOV RCAP2L,#0D2h ; sample period = 2 * T2 reload prd
007C 75CBFF 85 MOV RCAP2H,#0FFh ; = 2*(10000h-FFD2h)*1.085us
007F 75CCD2 86 MOV TL2,#0D2h ; = 2*46*1.085us
0082 75CDFF 87 MOV TH2,#0FFh ; = 99.8us
88
0085 75D840 89 MOV ADCCON2,#040h ; DMA mode
0088 75EF66 90 MOV ADCCON1,#066h ; Timer2 mode
91
008B D2AF 92 SETB EA ; enable interrupts
008D D2AE 93 SETB EADC ; enable ADC interrupt
94
95 ; LAUNCH DMA conversion... when finished, ADC interrupt will clear C
96
008F D2CA 97 SETB TR2 ; run Timer2 = start DMA
0091 D3 98 SETB C
0092 40FE 99 JC $ ; wait for DMA to finish
100
0094 00 101 NOP ;.................................... SET BREAKPOINT HERE
102
103 ; REPEAT entire program...
104
0095 80B4 105 JMP MAIN
106
107 ;____________________________________________________________________
108 ; SUBROUTINE
109
0097 110 GETSTOPFLAG: ; clears C if DPTR>=DMASTOP
0097 D3 111 SETB C
0098 E583 112 MOV A,DPH
009A B56005 113 CJNE A,DMASTOPH,RET1 ; C cleared if DPH>=DMASTOPH
009D E582 114 MOV A,DPL
009F B56100 115 CJNE A,DMASTOPL,RET1 ; C cleared if DPL>=DMASTOPL
00A2 22 116 RET1: RET
DMATIMER PAGE 3
117
118 ;____________________________________________________________________
119
120 END
VERSION 1.2h ASSEMBLY COMPLETE, 0 ERRORS FOUND
DMATIMER PAGE 4
ADCCON1. . . . . . . . . . . . . D ADDR 00EFH PREDEFINED
ADCCON2. . . . . . . . . . . . . D ADDR 00D8H PREDEFINED
DMACOUNT . . . . . . . . . . . . NUMB 0040H
DMAH . . . . . . . . . . . . . . D ADDR 00D3H PREDEFINED
DMAINIT. . . . . . . . . . . . . NUMB 0010H
DMAL . . . . . . . . . . . . . . D ADDR 00D2H PREDEFINED
DMAP . . . . . . . . . . . . . . D ADDR 00D4H PREDEFINED
DMASTART . . . . . . . . . . . . X ADDR 0000H
DMASTOP. . . . . . . . . . . . . X ADDR 0080H
DMASTOPH . . . . . . . . . . . . D ADDR 0060H
DMASTOPL . . . . . . . . . . . . D ADDR 0061H
DPH. . . . . . . . . . . . . . . D ADDR 0083H PREDEFINED
DPL. . . . . . . . . . . . . . . D ADDR 0082H PREDEFINED
EA . . . . . . . . . . . . . . . B ADDR 00AFH PREDEFINED
EADC . . . . . . . . . . . . . . B ADDR 00AEH PREDEFINED
GETSTOPFLAG. . . . . . . . . . . C ADDR 0097H
MAIN . . . . . . . . . . . . . . C ADDR 004BH
RCAP2H . . . . . . . . . . . . . D ADDR 00CBH PREDEFINED
RCAP2L . . . . . . . . . . . . . D ADDR 00CAH PREDEFINED
RET1 . . . . . . . . . . . . . . C ADDR 00A2H
SETUP. . . . . . . . . . . . . . C ADDR 005AH
TH2. . . . . . . . . . . . . . . D ADDR 00CDH PREDEFINED
TL2. . . . . . . . . . . . . . . D ADDR 00CCH PREDEFINED
TR2. . . . . . . . . . . . . . . B ADDR 00CAH PREDEFINED
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