Author Topic: Serial Linear Digital to Analog converter for use with Calculators  (Read 12059 times)

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Offline Keoni29

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I designed this digital to analog converter for use with calculators which lack of sufficient I/O. This is a 4 bit DAC which means that there are 16 possible voltage levels.

What do you think? :hyper:

Documentation:
Operating voltage: 3,3V-5V
Data has to be sent in like this:
xxxx01
Send data: Least significant first
The 01 at the beginning has to be sent in before the 4 bit word. This is due to the architecture of the "timing" circuit.
Example: Send 5:
0101 01

For use with calculators:
AXE code sample which outputs a sawtooth wave:
Spoiler For Spoiler:
Code: [Select]
.TEST
0->V
Repeat Getkey(15)
DAC(V
If V++ =16
0->V
End
End
0->port
Return
Lbl DAC
2->Port //Sends the first two bits indicating the end of a word
3->Port
1->Port
3->Port
For (4)  //Sends the 4 bit word to the DAC
If r1^2  //Part of the dec->bin conversion
2->Port
Else
1->Port
End
3->Port
r1/2->r1 //Part of the dec->bin conversion
End

I HAVEN'T BUILT ANYTHING YET, SO I DON'T KNOW WHERETHER IT WORKS OR NOT. THIS IS POTENTIALLY HARMFULL FOR YOUR CALCULATOR, SO STAY AWAY FROM IT UNTILL THE OPPOSITE HAS BEEN PROVEN.


Built da thing. Here 's how to make your own:
 http://www.omnimaga.org/index.php?action=dlattach;topic=13542.0;attach=13198
« Last Edit: July 10, 2012, 03:21:45 pm by Keoni29 »
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Offline aeTIos

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #1 on: June 01, 2012, 02:45:36 pm »
What should the clock speed be?
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Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #2 on: June 03, 2012, 03:46:38 am »
That will depend on the transfer rate of the calculator. As fast as you can get the software to run :)
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Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #3 on: June 08, 2012, 07:12:42 am »
I made a new more advanced, but simpeler design which uses less gates :)
It's made in Logisim, so I think the only one who can open it atm is aeTIos :P
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Offline aeTIos

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #4 on: June 08, 2012, 03:57:52 pm »
I guess you're wrong, lotsa ppl here know logisim. In fact, I discovered logisim via omni :P
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Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #5 on: June 08, 2012, 04:01:36 pm »
Oh ok. That's nice!
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Offline ralphdspam

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #6 on: June 08, 2012, 08:58:07 pm »
How about multiplexing it with an ADC as well?  I'm not really sure if you want to do that, but it would be nice to have a standardized analog I/O circuit to play with: microphones, light sensors, etc.
ld a, 0
ld a, a

Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #7 on: June 09, 2012, 03:34:29 am »
How about multiplexing it with an ADC as well?  I'm not really sure if you want to do that, but it would be nice to have a standardized analog I/O circuit to play with: microphones, light sensors, etc.
That's possible, but more complex than a separate DAC and ADC. I don't think the TI84+ is capable of recording sound and playing it back. The playback is possible, but the recording and processing is pretty much impossible without proper I/O. You could also just hook your calc up to an arduino since it features pwm and ADC.
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Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #8 on: June 25, 2012, 05:21:34 am »
Now building the DAC
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Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #9 on: June 25, 2012, 04:05:03 pm »


Only open this spoiler if you read this:
Replace the 2k2 resistors by 470 resistors.
Spoiler For Spoiler:
« Last Edit: July 09, 2012, 05:08:30 am by Keoni29 »
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Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #10 on: July 06, 2012, 05:13:53 am »
I'm going to solder this up this weekend. I made it on a solderless breadboard first and it works just fine. If there are other people interested in this device: just let me know. I'll release the source code for the subroutines which drive this thing.
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Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #11 on: July 09, 2012, 10:17:59 am »

I just soldered it up and I got it up and running. Also, I made an instructable which can be found down below.
« Last Edit: July 10, 2012, 03:22:03 pm by Keoni29 »
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Offline Keoni29

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #12 on: May 13, 2013, 08:07:14 am »
I featured it on my website:
http://8times8.host56.com/?p=206
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Offline DJ Omnimaga

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Re: Serial Linear Digital to Analog converter for use with Calculators
« Reply #13 on: June 07, 2013, 10:54:50 pm »
Interesting stuff Keoni. I'M not too sure how this works since I'm not into hardware, though, but isn't that the device that played Tennis for Two?