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F/+DAC1
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_39.ADF |
| Filename: | F/+DAC1 |
| Read OK: | ✔ |
| File size: | 09B3 bytes |
| Load address: | 2B204556 |
| Exec address: | 31434144 |
Duplicates
There is 1 duplicate copy of this file in the archive:
- Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_39.ADF » F/+DAC1
- Personal collection » Acorn hard disk » zipped_disks » elk03 » eug39/F/+DAC1
File contents
12 Bit DAC Instuctions ====================== This simple project is a 2 chip solution of how to convert from a digital numerical value, back into a 'real world' analogue voltage. Applications for a digital to analogue converter are very varied, from tuning a TV card fro m your computer to the generation of a custom (software definable) waveform - eg.sinewave, squarewave, sawtooth. ..PARTS...The circuit diagram shows electrically how to assemble the unit, requiring the following parts: 1x Maxim 7543 DAC chip (16 pin) 1x 16 pin DIL socket 1x 8 pin DIL socket 1x Cheap Op Amp,such as the 741 In addition,you'll need a low current power supply.It must be capable ofsupply ing +12v and -12v. BENEFITS...*Full 12 bit accuracy *Simple software control by just 3 serial wires *Full swing from 0v to 12v provided BUILD...1.Following the circuit diagram,the DAC is connected with its STB3 (pin 10) connected as the clock to the BBC user port line PB0.2. The data is shifted in on SRI (pin 7) and connected to the BBC's PB2 line.3. The command to load the serial data into the DAC's output latches is given by pulsing the load line, LD2 which goes to the BBCs PB1 on the user port.4. To ensure that the output of the DAC is the right way up (ie.from 0v to 12v not 0v to -12v) an Op Amp of gain -1 is used. This corrects the phase.5. The 5v requir ed by the registers inside the DAC come from the BBCs user port and the two circuits (the BBC and the DAC) are connected to common ground. DRIVER...The software is simplicity itself - on running the display will clear and thecomputer waits for a keyboard press. The arrow keys increment/decrement thevalue on the DAC output,displaying the numerical value of it (0 to 4095) on the screen. In addition ,pressing the 'A' key will toggle the state of the PB3 line on the user port,this was intended to turn on/off the AFC button on a TV tuner card. HINTS...*Use the +5v and -5v lines from the BBC instead of +12v and -12v if the range of voltages required does not exceed 0v and +5v. This saves on you having to build a seperate PSU. But remember you can't load the -5v line! *Socket the parts if possible, as this will facilitate easy replacements if you make a mistake and fry the chips. *Any pair of resistors will do by the opamp, as long as they are the same value and larger than about 1k. This is because the gain of an inverting opamp is approximately (Rfeedback/R in) FROM...Robert Sprowson. Happy soldering!
00000000 0d 31 32 20 42 69 74 20 44 41 43 20 49 6e 73 74 |.12 Bit DAC Inst| 00000010 75 63 74 69 6f 6e 73 0d 3d 3d 3d 3d 3d 3d 3d 3d |uctions.========| 00000020 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 0d 54 |==============.T| 00000030 68 69 73 20 73 69 6d 70 6c 65 20 70 72 6f 6a 65 |his simple proje| 00000040 63 74 20 69 73 20 61 20 32 20 63 68 69 70 20 73 |ct is a 2 chip s| 00000050 6f 6c 75 74 69 6f 6e 20 6f 66 20 68 6f 77 20 74 |olution of how t| 00000060 6f 20 63 6f 6e 76 65 72 74 20 66 72 6f 6d 20 61 |o convert from a| 00000070 0d 64 69 67 69 74 61 6c 20 6e 75 6d 65 72 69 63 |.digital numeric| 00000080 61 6c 20 76 61 6c 75 65 2c 20 62 61 63 6b 20 69 |al value, back i| 00000090 6e 74 6f 20 61 20 27 72 65 61 6c 20 77 6f 72 6c |nto a 'real worl| 000000a0 64 27 20 61 6e 61 6c 6f 67 75 65 0d 76 6f 6c 74 |d' analogue.volt| 000000b0 61 67 65 2e 20 41 70 70 6c 69 63 61 74 69 6f 6e |age. Application| 000000c0 73 20 66 6f 72 20 61 20 64 69 67 69 74 61 6c 20 |s for a digital | 000000d0 74 6f 20 61 6e 61 6c 6f 67 75 65 20 63 6f 6e 76 |to analogue conv| 000000e0 65 72 74 65 72 20 61 72 65 20 76 65 72 79 20 76 |erter are very v| 000000f0 61 72 69 65 64 2c 0d 66 72 6f 6d 20 74 75 6e 69 |aried,.from tuni| 00000100 6e 67 20 61 20 54 56 20 63 61 72 64 20 66 72 6f |ng a TV card fro| 00000110 20 6d 20 79 6f 75 72 20 63 6f 6d 70 75 74 65 72 | m your computer| 00000120 20 74 6f 20 74 68 65 20 67 65 6e 65 72 61 74 69 | to the generati| 00000130 6f 6e 20 6f 66 20 61 20 63 75 73 74 6f 6d 0d 28 |on of a custom.(| 00000140 73 6f 66 74 77 61 72 65 20 64 65 66 69 6e 61 62 |software definab| 00000150 6c 65 29 20 77 61 76 65 66 6f 72 6d 20 2d 20 65 |le) waveform - e| 00000160 67 2e 73 69 6e 65 77 61 76 65 2c 20 73 71 75 61 |g.sinewave, squa| 00000170 72 65 77 61 76 65 2c 20 73 61 77 74 6f 6f 74 68 |rewave, sawtooth| 00000180 2e 0d 0d 2e 2e 50 41 52 54 53 2e 2e 2e 54 68 65 |.....PARTS...The| 00000190 20 63 69 72 63 75 69 74 20 64 69 61 67 72 61 6d | circuit diagram| 000001a0 20 73 68 6f 77 73 20 65 6c 65 63 74 72 69 63 61 | shows electrica| 000001b0 6c 6c 79 20 68 6f 77 20 74 6f 20 61 73 73 65 6d |lly how to assem| 000001c0 62 6c 65 20 74 68 65 0d 75 6e 69 74 2c 20 72 65 |ble the.unit, re| 000001d0 71 75 69 72 69 6e 67 20 74 68 65 20 66 6f 6c 6c |quiring the foll| 000001e0 6f 77 69 6e 67 20 70 61 72 74 73 3a 0d 31 78 20 |owing parts:.1x | 000001f0 20 4d 61 78 69 6d 20 37 35 34 33 20 44 41 43 20 | Maxim 7543 DAC | 00000200 63 68 69 70 20 28 31 36 20 70 69 6e 29 0d 31 78 |chip (16 pin).1x| 00000210 1a 20 20 31 36 20 70 69 6e 20 44 49 4c 20 73 6f |. 16 pin DIL so| 00000220 63 6b 65 74 0d 31 78 20 20 38 20 70 69 6e 20 44 |cket.1x 8 pin D| 00000230 49 4c 20 73 6f 63 6b 65 74 0d 31 78 20 20 43 68 |IL socket.1x Ch| 00000240 65 61 70 20 4f 70 20 41 6d 70 2c 73 75 63 68 20 |eap Op Amp,such | 00000250 61 73 20 74 68 65 20 37 34 31 0d 0d 49 6e 20 61 |as the 741..In a| 00000260 64 64 69 74 69 6f 6e 2c 79 6f 75 27 6c 6c 20 6e |ddition,you'll n| 00000270 65 65 64 20 61 20 6c 6f 77 20 63 75 72 72 65 6e |eed a low curren| 00000280 74 20 70 6f 77 65 72 20 73 75 70 70 6c 79 2e 49 |t power supply.I| 00000290 74 20 6d 75 73 74 20 62 65 20 63 61 70 61 62 6c |t must be capabl| 000002a0 65 0d 6f 66 73 75 70 70 6c 79 20 69 6e 67 20 2b |e.ofsupply ing +| 000002b0 31 32 76 20 61 6e 64 20 2d 31 32 76 2e 0d 0d 42 |12v and -12v...B| 000002c0 45 4e 45 46 49 54 53 2e 2e 2e 2a 46 75 6c 6c 20 |ENEFITS...*Full | 000002d0 31 32 20 62 69 74 20 61 63 63 75 72 61 63 79 0d |12 bit accuracy.| 000002e0 2a 53 69 6d 70 6c 65 20 73 6f 66 74 77 61 72 65 |*Simple software| 000002f0 1a 20 63 6f 6e 74 72 6f 6c 1a 20 62 79 1a 20 6a |. control. by. j| 00000300 75 73 74 1a 20 33 20 73 65 72 69 61 6c 20 77 69 |ust. 3 serial wi| 00000310 72 65 73 0d 2a 46 75 6c 6c 20 73 77 69 6e 67 20 |res.*Full swing | 00000320 66 72 6f 6d 20 30 76 20 74 6f 20 31 32 76 20 70 |from 0v to 12v p| 00000330 72 6f 76 69 64 65 64 20 0d 0d 42 55 49 4c 44 2e |rovided ..BUILD.| 00000340 2e 2e 31 2e 46 6f 6c 6c 6f 77 69 6e 67 20 74 68 |..1.Following th| 00000350 65 20 63 69 72 63 75 69 74 20 64 69 61 67 72 61 |e circuit diagra| 00000360 6d 2c 74 68 65 20 44 41 43 20 69 73 20 63 6f 6e |m,the DAC is con| 00000370 6e 65 63 74 65 64 20 77 69 74 68 20 69 74 73 20 |nected with its | 00000380 53 54 42 33 0d 28 70 69 6e 20 31 30 29 20 20 63 |STB3.(pin 10) c| 00000390 6f 6e 6e 65 63 74 65 64 20 61 73 20 74 68 65 20 |onnected as the | 000003a0 63 6c 6f 63 6b 20 74 6f 20 74 68 65 20 42 42 43 |clock to the BBC| 000003b0 20 75 73 65 72 20 70 6f 72 74 20 6c 69 6e 65 20 | user port line | 000003c0 50 42 30 2e 32 2e 20 54 68 65 20 64 61 74 61 0d |PB0.2. The data.| 000003d0 69 73 20 73 68 69 66 74 65 64 20 69 6e 20 6f 6e |is shifted in on| 000003e0 20 53 52 49 20 28 70 69 6e 20 37 29 20 61 6e 64 | SRI (pin 7) and| 000003f0 20 63 6f 6e 6e 65 63 74 65 64 20 74 6f 20 74 68 | connected to th| 00000400 65 20 42 42 43 27 73 20 50 42 32 20 6c 69 6e 65 |e BBC's PB2 line| 00000410 2e 33 2e 20 54 68 65 0d 63 6f 6d 6d 61 6e 64 20 |.3. The.command | 00000420 74 6f 20 6c 6f 61 64 20 74 68 65 20 73 65 72 69 |to load the seri| 00000430 61 6c 20 64 61 74 61 20 69 6e 74 6f 20 74 68 65 |al data into the| 00000440 20 44 41 43 27 73 20 6f 75 74 70 75 74 20 6c 61 | DAC's output la| 00000450 74 63 68 65 73 20 69 73 20 67 69 76 65 6e 20 20 |tches is given | 00000460 62 79 0d 70 75 6c 73 69 6e 67 20 74 68 65 20 6c |by.pulsing the l| 00000470 6f 61 64 20 6c 69 6e 65 2c 20 4c 44 32 20 77 68 |oad line, LD2 wh| 00000480 69 63 68 20 67 6f 65 73 20 74 6f 20 74 68 65 20 |ich goes to the | 00000490 42 42 43 73 20 50 42 31 20 6f 6e 20 74 68 65 20 |BBCs PB1 on the | 000004a0 75 73 65 72 20 70 6f 72 74 2e 34 2e 0d 54 6f 20 |user port.4..To | 000004b0 65 6e 73 75 72 65 20 74 68 61 74 20 74 68 65 20 |ensure that the | 000004c0 6f 75 74 70 75 74 20 6f 66 20 20 74 68 65 20 44 |output of the D| 000004d0 41 43 20 69 73 20 74 68 65 20 72 69 67 68 74 20 |AC is the right | 000004e0 77 61 79 20 75 70 20 28 69 65 2e 66 72 6f 6d 20 |way up (ie.from | 000004f0 30 76 20 74 6f 0d 31 32 76 20 20 6e 6f 74 20 30 |0v to.12v not 0| 00000500 76 20 74 6f 20 2d 31 32 76 29 20 61 6e 20 4f 70 |v to -12v) an Op| 00000510 20 41 6d 70 20 6f 66 20 67 61 69 6e 20 2d 31 20 | Amp of gain -1 | 00000520 69 73 20 75 73 65 64 2e 20 54 68 69 73 20 63 6f |is used. This co| 00000530 72 72 65 63 74 73 20 74 68 65 0d 70 68 61 73 65 |rrects the.phase| 00000540 2e 35 2e 20 54 68 65 20 35 76 20 72 65 71 75 69 |.5. The 5v requi| 00000550 72 20 65 64 20 62 79 20 74 68 65 20 72 65 67 69 |r ed by the regi| 00000560 73 74 65 72 73 20 69 6e 73 69 64 65 20 74 68 65 |sters inside the| 00000570 20 44 41 43 20 63 6f 6d 65 20 66 72 6f 6d 20 74 | DAC come from t| 00000580 68 65 0d 42 42 43 73 20 75 73 65 72 20 70 6f 72 |he.BBCs user por| 00000590 74 20 20 61 6e 64 20 74 68 65 20 74 77 6f 20 63 |t and the two c| 000005a0 69 72 63 75 69 74 73 20 28 74 68 65 20 42 42 43 |ircuits (the BBC| 000005b0 20 61 6e 64 20 74 68 65 20 44 41 43 29 20 61 72 | and the DAC) ar| 000005c0 65 20 63 6f 6e 6e 65 63 74 65 64 0d 74 6f 20 63 |e connected.to c| 000005d0 6f 6d 6d 6f 6e 20 20 67 72 6f 75 6e 64 2e 20 44 |ommon ground. D| 000005e0 52 49 56 45 52 2e 2e 2e 54 68 65 20 73 6f 66 74 |RIVER...The soft| 000005f0 77 61 72 65 20 69 73 20 73 69 6d 70 6c 69 63 69 |ware is simplici| 00000600 74 79 20 69 74 73 65 6c 66 20 2d 20 6f 6e 20 72 |ty itself - on r| 00000610 75 6e 6e 69 6e 67 0d 74 68 65 20 64 69 73 70 6c |unning.the displ| 00000620 61 79 20 77 69 6c 6c 20 63 6c 65 61 72 20 61 6e |ay will clear an| 00000630 64 20 74 68 65 63 6f 6d 70 75 74 65 72 20 77 61 |d thecomputer wa| 00000640 69 74 73 20 66 6f 72 20 61 20 6b 65 79 62 6f 61 |its for a keyboa| 00000650 72 64 20 70 72 65 73 73 2e 0d 0d 54 68 65 20 61 |rd press...The a| 00000660 72 72 6f 77 20 6b 65 79 73 20 69 6e 63 72 65 6d |rrow keys increm| 00000670 65 6e 74 2f 64 65 63 72 65 6d 65 6e 74 20 74 68 |ent/decrement th| 00000680 65 76 61 6c 75 65 20 6f 6e 20 74 68 65 20 44 41 |evalue on the DA| 00000690 43 20 6f 75 74 70 75 74 2c 64 69 73 70 6c 61 79 |C output,display| 000006a0 69 6e 67 0d 74 68 65 20 6e 75 6d 65 72 69 63 61 |ing.the numerica| 000006b0 6c 20 76 61 6c 75 65 20 6f 66 20 69 74 20 28 30 |l value of it (0| 000006c0 20 74 6f 20 34 30 39 35 29 20 6f 6e 20 74 68 65 | to 4095) on the| 000006d0 20 73 63 72 65 65 6e 2e 20 49 6e 20 61 64 64 69 | screen. In addi| 000006e0 74 69 6f 6e 20 2c 70 72 65 73 73 69 6e 67 0d 74 |tion ,pressing.t| 000006f0 68 65 20 27 41 27 20 6b 65 79 20 77 69 6c 6c 20 |he 'A' key will | 00000700 74 6f 67 67 6c 65 20 74 68 65 20 73 74 61 74 65 |toggle the state| 00000710 20 6f 66 20 74 68 65 20 50 42 33 20 6c 69 6e 65 | of the PB3 line| 00000720 20 6f 6e 20 74 68 65 20 75 73 65 72 20 70 6f 72 | on the user por| 00000730 74 2c 74 68 69 73 0d 77 61 73 20 69 6e 74 65 6e |t,this.was inten| 00000740 64 65 64 20 74 6f 20 74 75 72 6e 20 6f 6e 2f 6f |ded to turn on/o| 00000750 66 66 20 74 68 65 20 41 46 43 20 62 75 74 74 6f |ff the AFC butto| 00000760 6e 20 6f 6e 20 61 20 54 56 20 20 74 75 6e 65 72 |n on a TV tuner| 00000770 20 63 61 72 64 2e 0d 0d 48 49 4e 54 53 2e 2e 2e | card...HINTS...| 00000780 2a 55 73 65 20 74 68 65 20 2b 35 76 20 61 6e 64 |*Use the +5v and| 00000790 20 2d 35 76 20 6c 69 6e 65 73 20 66 72 6f 6d 20 | -5v lines from | 000007a0 74 68 65 20 42 42 43 20 69 6e 73 74 65 61 64 20 |the BBC instead | 000007b0 6f 66 20 2b 31 32 76 20 61 6e 64 20 2d 31 32 76 |of +12v and -12v| 000007c0 0d 69 66 20 74 68 65 20 72 61 6e 67 65 20 6f 66 |.if the range of| 000007d0 20 76 6f 6c 74 61 67 65 73 20 72 65 71 75 69 72 | voltages requir| 000007e0 65 64 20 64 6f 65 73 20 6e 6f 74 20 65 78 63 65 |ed does not exce| 000007f0 65 64 20 30 76 20 61 6e 64 20 2b 35 76 2e 20 54 |ed 0v and +5v. T| 00000800 68 69 73 20 73 61 76 65 73 0d 6f 6e 20 79 6f 75 |his saves.on you| 00000810 20 68 61 76 69 6e 67 20 74 6f 20 62 75 69 6c 64 | having to build| 00000820 20 61 20 73 65 70 65 72 61 74 65 20 50 53 55 2e | a seperate PSU.| 00000830 20 42 75 74 20 72 65 6d 65 6d 62 65 72 20 79 6f | But remember yo| 00000840 75 20 63 61 6e 27 74 20 6c 6f 61 64 20 74 68 65 |u can't load the| 00000850 20 2d 35 76 0d 6c 69 6e 65 21 0d 0d 2a 53 6f 63 | -5v.line!..*Soc| 00000860 6b 65 74 20 74 68 65 20 70 61 72 74 73 20 69 66 |ket the parts if| 00000870 20 70 6f 73 73 69 62 6c 65 2c 20 61 73 20 74 68 | possible, as th| 00000880 69 73 20 77 69 6c 6c 20 66 61 63 69 6c 69 74 61 |is will facilita| 00000890 74 65 20 65 61 73 79 20 72 65 70 6c 61 63 65 6d |te easy replacem| 000008a0 65 6e 74 73 0d 69 66 20 79 6f 75 20 6d 61 6b 65 |ents.if you make| 000008b0 20 61 20 6d 69 73 74 61 6b 65 20 61 6e 64 20 66 | a mistake and f| 000008c0 72 79 20 74 68 65 20 63 68 69 70 73 2e 0d 2a 41 |ry the chips..*A| 000008d0 6e 79 20 70 61 69 72 20 6f 66 20 72 65 73 69 73 |ny pair of resis| 000008e0 74 6f 72 73 20 77 69 6c 6c 20 64 6f 20 62 79 20 |tors will do by | 000008f0 74 68 65 20 6f 70 61 6d 70 2c 20 61 73 20 6c 6f |the opamp, as lo| 00000900 6e 67 20 61 73 20 74 68 65 79 20 61 72 65 20 74 |ng as they are t| 00000910 68 65 20 73 61 6d 65 0d 76 61 6c 75 65 20 61 6e |he same.value an| 00000920 64 20 6c 61 72 67 65 72 20 74 68 61 6e 20 61 62 |d larger than ab| 00000930 6f 75 74 20 31 6b 2e 20 54 68 69 73 20 69 73 20 |out 1k. This is | 00000940 62 65 63 61 75 73 65 20 74 68 65 20 67 61 69 6e |because the gain| 00000950 20 6f 66 20 61 6e 20 69 6e 76 65 72 74 69 6e 67 | of an inverting| 00000960 0d 6f 70 61 6d 70 20 69 73 20 61 70 70 72 6f 78 |.opamp is approx| 00000970 69 6d 61 74 65 6c 79 20 28 52 66 65 65 64 62 61 |imately (Rfeedba| 00000980 63 6b 2f 52 20 69 6e 29 0d 0d 46 52 4f 4d 2e 2e |ck/R in)..FROM..| 00000990 2e 52 6f 62 65 72 74 20 53 70 72 6f 77 73 6f 6e |.Robert Sprowson| 000009a0 2e 0d 48 61 70 70 79 20 73 6f 6c 64 65 72 69 6e |..Happy solderin| 000009b0 67 21 0d |g!.| 000009b3
F/+DAC1.m0
F/+DAC1.m1
F/+DAC1.m2
F/+DAC1.m4
F/+DAC1.m5
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