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Parallel JP1 interface not working anymore?

 
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toddk63



Joined: 17 Apr 2006
Posts: 10

                    
PostPosted: Sun Jan 09, 2011 11:58 am    Post subject: Parallel JP1 interface not working anymore? Reply with quote
...on a RS 15-2104. Last time I used it on this remote was March of 2009 so it is the same computer. The only difference I can think of is that I had to remove the backlighting from it cause it was flaking out with it, not sure when I did that.

I tried all the battery combinations and other usual suggestions. After I get the failure notice when checking interface, the remote LED flashes twice.

So then I jumpered the diode and it passed the interface check. Jumpered in a new signal diode ( tried several) and same problem. Then I soldered pins 18-25 together to cover my bases on the ground. While I was at it, I also "upgraded" the 10k resistors with 1k. I do not have on hand a Schottky diode, will try it when I can get one.

The funny thing is I was able to download the remote to the PC with the diode bypassed. So why is the diode in there anyways?

The only other JP1 remote I have is an URC 8910 but its at my fathers house so will have to wait to try it on that one as well.



Thanks,

Todd K.
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cauer29



Joined: 03 Feb 2010
Posts: 236

                    
PostPosted: Sun Jan 09, 2011 1:17 pm    Post subject: Re: Parallel JP1 interface not working anymore? Reply with quote
toddk63 wrote:
...on a RS 15-2104. Last time I used it on this remote was March of 2009 so it is the same computer. The only difference I can think of is that I had to remove the backlighting from it cause it was flaking out with it, not sure when I did that.

I tried all the battery combinations and other usual suggestions. After I get the failure notice when checking interface, the remote LED flashes twice.

So then I jumpered the diode and it passed the interface check. Jumpered in a new signal diode ( tried several) and same problem. Then I soldered pins 18-25 together to cover my bases on the ground. While I was at it, I also "upgraded" the 10k resistors with 1k. I do not have on hand a Schottky diode, will try it when I can get one.

The funny thing is I was able to download the remote to the PC with the diode bypassed. So why is the diode in there anyways?

The only other JP1 remote I have is an URC 8910 but its at my fathers house so will have to wait to try it on that one as well.



Thanks,

Todd K.


I'm going to assume here that you have a JP1 "simple" interface and not one of the more advanced designs, since you're referring to a diode. The most common issue with the simple interface is battery level. If it's low or high, or batteries not present or present, it may cause the issue that you're seeing. It all depends. Any of those conditions can change a working JP1 simple into a non-working one. So, try fresh batteries and try removing them entirely and try using old weak batteries and try reversing one cell, assuming this is a 4 cell remote.

As to the purpose of the diode, operation of the JP1 simple interface is explained in the file

http://www.hifi-remote.com/forums/dload.php?action=file&file_id=4562

where it says:

The SDA line is controlled by the DØ output through the diode. When DØ is high the diode is reverse biased. Under this condition the processor can send and receive data to the EEPROM on the SDA line, and the EEPROM can send data to the PC on the S7 line. When the processor output is in tri-state, a low on DØ will pull down on the SDA line through the diode, and a high will let R19 pull up on it. That's the way the PC sends data to the EEPROM.

The diode is necessary to allow bi-directional communication on the I2C data line.

A.A.
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toddk63



Joined: 17 Apr 2006
Posts: 10

                    
PostPosted: Wed Jan 19, 2011 2:45 pm    Post subject: Problem solved Reply with quote
OK. I got the URC 8910 and tried it again. Same problem. Then I swapped out the plain diode for a Schottky Diode and that was the ticket! It worked.

So if you are having problems with your simple parallel interface cable, make sure it has a Schottky diode and not just any ol' diode
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