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Trouble making 634 display work off of a TiVo

dsegel

New member
I'm trying to get a CFA634-YMC-KS work with my TiVo and I'm not having much luck. I'm driving it externally via a native version of lcdproc (LCDd) that I compiled for my Series 1 Tivo, but all I get is the blinking cursor. I know the Tivo is sending the proper data out because if I connect it to a PC and run Hyperterm I can see the data lcdproc is sending out the serial port.

The display also works fine when connected to a PC. I can use either lcdproc or CrystalControl succesfully.

I'm using power taken off of an unused hard drive power connector inside the unit and routed to an external connector. The display boots up fine, so I don't think the problem is with the power.

The serial signal is being taken via the external serial port on the back of the TiVo. As I stated above, I see the data correctly if I run the data cable to a serial port on a PC, but if I connect it to the 634 I get nothing.

Any tips or suggestions? I've tried different speeds, but it doesn't seem to make a difference.
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CF Tech

Administrator
Make sure there is +5v to both the "+5v(LCD)" and "+5v(LED)" pins. You know this is OK if the boot screen comes on.

Make sure your cable is such that the data comes in on the correct pin. Check the "Connectiong your LCD" section in the data sheet.
 

dsegel

New member
The power's fine; the LCD boots up and displays the CF logo, then the cursor appears in the upper left corner and starts blinking. The backlight is on.

The data is definitely coming over the line; I just checked it again by hooking it into the COM port of another PC and running Hyperterm. I see the data on the serial line and it looks fine, but the display is simply ignoring it. I've tried both the 9-pin connector (J1) and the Data In connector on J2 with the same results.

Does the LCD have some special requirements for voltage on the serial line? Is it more sensitive than a typical serial port might be? When I hooked it up to the COM port I just used the Tx and Ground lines, nothing else.
 

CF Tech

Administrator
What serial cable are you using?

If it works PC to PC, it will not work PC to LCD.

You may need a different cable. Try our WR232Y01, which is like a Radio Shack 26-152a.

Or try putting in a null-modem adaptor.
 
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dsegel

New member
I was using the proper cable. I believe I had a null modem adapter in place when connected to the PC, but not when connected to the TiVo. I actually tried the TiVo both with and without the adapter.

At this point it really looks like my TiVo is not putting out the appropriate voltages on the serial port. The PCs seem to be able to deal with the lower-voltage signal OK, but the 634 ignores it.
 

CF Tech

Administrator
Try closing JPE on the CFA-634. This change will make the CFA-634 look for a 0v to 5v ("logic level") signal instead of the full RS-232 levels.
 

dsegel

New member
Is there any danger in doing this if the voltages actually go above +5V or go negative? The signal I'm trying to use is supposed to be a true RS232 format (i.e. up to +/-12V), but it really looks like it's closer to +/-8V.

Wouldn't the values (on/off, mark/space) be backwards if I connected it this way?
 

dsegel

New member
I haven't actually tried it with the JPE jumper closed. I think you would also have to close the JPB jumper as well because RS232 and Logic level signals are reversed as well as being different voltages.

The serial port on the TiVo is supposed to be a true RS232C-compliant port, meaning it should be putting out +/-12V, with -12V = 1 and +12V = 0 (or thereabouts - most serial ports don't actually achieve 12V.)

Closing the JPE jumper makes the LCD display accept logic-level input, meaning it would be expecting a 0 or 5V signal with 0V = 0 and 5V = 1. In that case you would also have to close JPB so it treated the negative voltage coming from the serial port as 1 and the positive voltage as 0. In theory, at least.

It might work, but I'm not willing to submit my LCD to a test of this. In the meantime my LCD works perfectly off of a PC serial port but acts as if there is no signal when connected to the TiVo. As stated above, it ought to work as is.

I may get brave now that you've dug this up again. I'll let you know if I do.
 

wdwms

New member
Knight said:
Is the TiVo a series One, or two?

My series one works fine with a LCD screen, and LCDproc.
Series one SAs work fine, it is the Series SA Dtivos that have issues... can you send me your LCDproc binary? interested in seeing that on my tivo..

-t
 

wdwms

New member
dsegel said:
I haven't actually tried it with the JPE jumper closed. I think you would also have to close the JPB jumper as well because RS232 and Logic level signals are reversed as well as being different voltages.

The serial port on the TiVo is supposed to be a true RS232C-compliant port, meaning it should be putting out +/-12V, with -12V = 1 and +12V = 0 (or thereabouts - most serial ports don't actually achieve 12V.)

Closing the JPE jumper makes the LCD display accept logic-level input, meaning it would be expecting a 0 or 5V signal with 0V = 0 and 5V = 1. In that case you would also have to close JPB so it treated the negative voltage coming from the serial port as 1 and the positive voltage as 0. In theory, at least.

It might work, but I'm not willing to submit my LCD to a test of this. In the meantime my LCD works perfectly off of a PC serial port but acts as if there is no signal when connected to the TiVo. As stated above, it ought to work as is.

I may get brave now that you've dug this up again. I'll let you know if I do.
Ok i'm working w/a guy w/the same problem on a Dtivo.. lcd set to 9600.. he can see stuff through a term hooked up to the serial port, however the LCD acts like it is not getting data.

What jumpers should he try closing?
 

dsegel

New member
OK...a few comments to add to the discussion:

1. My TiVo is a standalone Series 1, so whatever problems it has are probably not the same as the DTiVo's have. Or maybe they are.

I'm pretty sure the TiVo serial port was operating at 9600 baud when I last tried it with the LCD; that's the speed that worked when I connected it to the PC.

I still haven't gotten around to trying it again on the TiVo I will report back if/when I ever do, though.
 

wdwms

New member
Rob went through all of the 632's jumper settings for input and nothing worked.. we are really stumped.. If he runs the tivo output through a baud rate converter, from 9600 to 9600, the LCD works fine. But hook up tivo directly to the LCD and we get nothing..

CF Tech.. hints? need us to hook up a volt meter?

-t
 

CF Tech

Administrator
If you want to pack up the whole system with the converter in place working, I'll hook it up to the 'scope and see what is going on. Can't really do much more remotely.
 

wdwms

New member
CF Tech said:
If you want to pack up the whole system with the converter in place working, I'll hook it up to the 'scope and see what is going on. Can't really do much more remotely.
Ok i'll contact you via PM to get shipping info. I configured a script on the box that updates the LCD every 5 seconds. The tivo can be booted w/out a satellite dish, provided you have it connected to a network w/DHCP you can telnet right in and run the script.

-Todd
 

zora

New member
Hi, I know that this thread is a few months old, but I was wondering if anything ever came of it. I have a Direct Tivo Series 2 and a CFA634-TFB-KU and seem to be having the same problem, though I have not hooked the Tivo up to the PC and see if it is sending the right signals throught the serial port.


Thanks,


Bryon
 
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