Ron, John, anybody, what is "Incorrect charx" in U

[Mastiff]

My brother made an UIRT for me, and I get a weird message all the time: "Incorrect charx" What does this mean, and how do I fix it? I've got it on Com2, all the other ports are occupied with other things (Barco projector, X-10 and an ISDN adapter). I hope somebody can help me out here, I'm pretty new to this UIRT stuff! It works nicely with the UIR plug-in. I thought I had it, but it turned out that turning off the init only took away the error message. It still won't receive anything.
Please help me! Thanks a lot in advance...

[Ron]

moved to UIRT forum.

[Mastiff]

I tried it here once (a couple of months ago) without anything even after a bump except for a guy asking for the prints for an UIRT, so I wanted to try it in the regular forum. Didn't you write the driver, by the way? It said your name and John's when I checked. I would really like to know at least what the message means.

[Bitmonster]

Is this a UIRT2 or an old UIRT-like device?

The error message seems to indicate that there is a problem with the communication between the UIRT and the PC. I think that this error indicates a checksum error of the communication. I would try the following things:

1. Test if the device gets enough voltage. ( especially if this is an old UIRT-like device try to use an external power supply)
2. Try to use a short serial cable or no cable at all.
3. Test the device with another PC
4. Only use the RXD, TXD and GND lines of the serial port. (for UIRT2 or UIRT with external power)
5. Make shure the PIC is flashed with the right firmware and verify the programming.

When I started with PIC programming I had a similar problem once. Everything seems to be fine on my bench setup, but after I used the device on another PCB it stopped working the right way. I tested the code and hardware weeks before I actually found the problem.

The flash-memory is sensitive to different supply voltages. So if you test the device with 5,00 V everything might work. But if the voltage drops down to lets say 4,90 V some bits may read out a different value. This is the reason why "production" programmers test the device at different supply voltages before they assume the programming is correct. After I used another programmer the problem was away forever. So maybe reprogramming with an external programmer might help.

My only problem with the UIRT2 was the known problem with the unreliable receiving. After I used some additional caps at the IR-receiver the device is now working extremly reliable. The device is connected to a 24/365 computer and never hung up or something like that.

Bitmonster

[Bitmonster]

OK, I've read your old post and it seems to be an old UIRT without external power supply. The main problem with this device is, that the serial port is no good power source and modern mainboards are even worse in this aspect. So I would suggest to modify the circuit with an external power supply. One possible source of 5 V might be an USB port. A modified USB cable is easy to make. But you have to modify the circuit if you use the PC as power supply because the UIR uses another GND level. So to simply test it you should use a completly independant supply with a free GND level. After that I would suggest to use the UIRT2 design anyway.

Bitmonster

[Mastiff]

Thanks! My brohter is actually working on a UIRT2 for me right now, but that's for another computer. So I would really like to get this one working as well. How about taking the 5V directly from one of the red harddisk cables? Is that the same 5V that the com port gives out? It would be easier, and I won't have to kill an USB cable. And where do I connect this? Remember I'm an idiot when it comes to electronics (well, I'm pretty much an allrounder in the idiocy department, but leave that for now...) so please tell me what kind of soldering point I should use in a way that even I understand. Like: "Solder it to the left leg of the round thingy with these and these numbers on it." :D

[Bitmonster]

In principal the red powercable on a HD-connector would work.
BUT:
As I previously said, you cannot connect the PC power to an UIRT1 without much modification of the circuit. This is because the UIRT uses another GND potential then the PC but this potential is actually derivered from the PC. So if you connect it this way you would actually short circuit the device. To test if additional power would improve everything I would use an external stabilized wall power supply with 5V output and no earth connector. But even then you have to modify a lot on the device which is no job for an electronicly unscilled person.

Because the PIC is actually the most expensive part of the whole device and can be used on both the UIRT1 and 2, I would suggest that you wait for the UIRT2 to complete, test it and if everything works use the the old UIRT1 as a part source for another UIRT2. This is less hassle and an UIRT2 is much superior than an UIRT1.

Bitmonster

[Mastiff]

Thanks! I'll just wait for my brother to get off his butt, then. He promised me to do it after Easter. And I can keep the UIRT 1 for UIR use. The weird thing is that if I set it up as an UIR in the UIR/IRMan plugin, I get codes flying all over the place. But if I set it up as an IRMan, they are 100 % consistent, which is what I need. But whatever works... :D

[Ron]

Didn't you write the driver, by the way? It said your name and John's when I checked. I would really like to know at least what the message means.

I think John based the driver on my UIR driver, that's why my name is in there. Other then that I have no idea what is in that driver. The message probably means that the attached device did not send the correct identification character. ( RS232 communication problems, incorrect device,.. ).

[Mastiff]

OK, thanks, Ron. And with the help of Bitmonster I have recognized that my present ways have unsurmountable obstacles, so I'll take the chicken way out and wait for my brother! :D