How do I send Synchronous Serial to a Display w CS, CLK, and DATA pins?
Russ Ferguson
Posts: 206
I picked up a surplus Noritake VFD having Synchronous Serial input hoping that it would be fairly obvious how to connect it to a BS2, but haven't had any success yet.
After searching through the·Nuts and Volts articles·I·started trying to send data to the VFD using·SHIFTOUT. So far - the results would lead me to think that I don't even have power connected to it (except that the 5v regulator starts warming up).
I am attaching the spec sheet and the code I have tried.
Anyone know how to do this?
After searching through the·Nuts and Volts articles·I·started trying to send data to the VFD using·SHIFTOUT. So far - the results would lead me to think that I don't even have power connected to it (except that the 5v regulator starts warming up).
I am attaching the spec sheet and the code I have tried.
Anyone know how to do this?
Comments
·· Try setting the CS line HIGH.· The documentation doesn't indicate it's an active LOW control line.· Also, try it without making the CLK line HIGH...Not sure why that's there.· Let us know what happens.· Good luck.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
I tried both ideas and still did not see anything.
I have two of the little displays and they both behave the same way. Didn't invest any real money in them, but will keep trying to get them to work as they are interesting to look at.
I have a 5v supply with a pretty good current rating (old PC power supply). The display is on a bread board with a BS2-OEM. I am using some 220 ohm resistors between the 3 stamp pins and the display pins. Volt meter shows power and ground everywhere. Sid's stamp tester shows the BS2 to be in good working order.
·· In case PC P/S is generating any kind of noise the VFD may not like, do you have another supply with at least 300mA of current capability?· One more thing I should've mentioned...You have the LSBFIRST setting in your SHIFTOUT, but have you tried MSBPOST?· Without full documentation it's hard to know but I will see if I can find anything else.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
·· You know, you may be on to something with having set the CLK line HIGH.· I am looking at our datasheet for the VFD we have from Noritake and it shows that line HIGH as well.· Still, I think the CS line may be active high as well...Of course, you could have your program send data to it in both states to be sure.
BTW, the display we have gets the data via SPI LSB first, so...you can also disregard my previous post where I didn't think before I typed that line.·
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Chris Savage
Parallax Tech Support
csavage@parallax.com
I attached the code that I just tested.
Time for me to turn. I really appreciate your encouragement and will check back in tomorrow.
·· Does that code work?· If not I have one more suggestion.· You have a PULSOUT after your SHIFTOUT.· Don't know why I didn't notice this before, but typically on SPI devices the line is activated prior to communication and de-activated after.· The PULSOUT never really lets the line de-activate (not stay that way).· Try replacing it with the opposite state you're using to activate the device.· When you use HIGH CS, follow the SHIFTOUT with LOW CS, and visa versa.· In many devices this is what tells the device to use the incoming data and I can see this being a possible problem.· BTW, you can request a full datasheet from Noritake.· I don't know how long it will take to get it, but it couldn't hurt to have it.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
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Chris Savage
Parallax Tech Support
csavage@parallax.com
If there is a contrast circuit, make sure that it's set up correctly. Just as a matter of information (which may or may not apply to this LCD), some LCD's use a negative voltage in the contrast circuit.
Regards,
Bruce Bates
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Post Edited (Bruce Bates) : 6/13/2006 5:08:38 AM GMT
Chris - I will modify the code tonight and try again. After going through Noritake screens to download the spec brief, I did get a call from them. Very friendly and ready to help, most important to them was that this display was not in production and that I should be using their newest version. I will call the guy back and ask for full documentation.
PJ - I appreciate you uploading the spec sheet that you found. The "Software Commands" section is a big contribution.
Bruce - There does not appear to be any hardware contrast control on the display. The "Software Commends" may be the equivalent. Won't know of course until I have some indication that it is receiving the data I send it.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
Post Edited (Chris Savage (Parallax)) : 6/13/2006 2:29:19 PM GMT
In any case I am ready to try it again. This time with some inlightenment about what needs to happen.
Success !
Very nice display.
The code is attached, and needs to be re-written·to use·subroutines of course.
I owe a big "Thank you" to·Chris, PJ and Bruce
Post Edited (Russ) : 6/14/2006 2:23:26 AM GMT
Good on ya, mate.
Post Edit --
Looking at your program, you're using SEROUT -- so it's serial data (asynch), then.· Is it CS or /CS?· What's the scoop on all that?
Post Edited (PJ Allen) : 6/14/2006 3:15:38 AM GMT
That code I loaded does not have a SEROUT in it anywhere. And yes I downloaded just to double check that I put the right one up.
Please explain?
·· Congrats!· I just looked at your code...We were so close...Of course, without turning the display ON we'd never see anything now, would we?·
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Chris Savage
Parallax Tech Support
csavage@parallax.com