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Topic: Need some advice on a Digital Potentiometer (Read 6608 times) previous topic - next topic

TchnclFl

Haha I took a look at page 47, and it is complete gibberish to me.  I don't get why there are numbers and letters all in that chart!

Maybe if I randomly put high voltage into it the magic smoke will solve my problems ;D.

Osgeld

#46
Apr 22, 2010, 04:18 am Last Edit: Apr 22, 2010, 04:32 am by Osgeld Reason: 1
ok I think I understand it ok, but I have no idea if this simplification works

replace the commandByte with

00000000 to write to pot 2
00010000 to write to pot 1

the first 4 bits are a register address 0 pot 0 and 1 pot 1,  2 & 3 are reserved, 4 is the terminal connector register, where you can connect and disconnect individual pins of each pot and control its behaviour on a shutdown signal (page 36), 5 is the status register to read if something is in a shutdown state the rest are reserved

bits 5 & 6 are the command bits (page 47)

Quote
11 Read Data 16-Bits
00 Write Data 16-Bits
01 Increment 8-Bits
10 Decrement 8-Bits


and 7 & 8 are data bits, and this is where I get confused

if you want to send a 8 bit command you can use the inc / dec functions above to (I presume) jump a few steps at a time

if you send it a 2 byte command, you now have 10 data bits, BUT the msb (bit 7 of byte 1) is not used for input, the next bit (bit 8 of byte 1) I think sets it into "normal" or "full scale" modes followed by the real data (byte 2)


:-?

edit :: also look at the table on page 48, only look at function, command, and SDI pin
http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

TchnclFl

Wow I'm even more confused now haha.  I'll get some sleep and start experimenting tomorrow once I'm more rested :).

Osgeld

http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

TchnclFl

#49
Apr 22, 2010, 09:25 pm Last Edit: Apr 22, 2010, 10:30 pm by Tchnclfl Reason: 1
Well, I don't know how you did it, but those commands magically work!  Thanks a ton!

Any chance of a command to write to both pots?  I've noticed that when you write to one, the other seems to reset (to 127).

[edit]Actually, it turns out I can send them both commands to write a value, but I have to do it seperately, and Pot1 doesn't seem to be quite right (seems to skip about half of the commands).[/edit]

[edit]Nevermind, all is good now!  Almost done with the library![/edit]

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