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Lakee911



Joined: 14 Oct 2003
Posts: 6
Location: Columbus, Ohio, USA

PostPosted: Tue Oct 14, 2003 7:22 am    Post subject: Intermitent Results Reply with quote

Hi All,
I'm new to this JP1 stuff, but I'm pretty excited about it. I built the simple interface the other day, with 10K resistors, and the recomended diode. I shorted all the grounds together too. I have a laptop (Dell Insiron 8100) with WinXP. I couldn't get the Check Interface to work, but I was able to download from the remote. Very Happy I used a Scientific Explorerer 3 Remote, the one that came with my Time Warner Cable Box. I thought everything worked fine. I don't think I had batterries in my remote when I tried it.
I'm unable to download from the remote and I've not changed a thing. All I did was close the program and open it up later to fool around with. I openned up the adapter to check for shorts and I found none. I've tried many different sets of batteries, new, old, half used, etc. Tried plugging in cable frontwards and backwards, all to no go. It tells me that it didn't receive a responses when sending the address to the remote, yet the remote's LED blinks when it tries to download. I figured I must have fried the damn thing, but it still works with the cable box. I'm really confused why it'd work and then all of a sudden crap out. Crying or Very sad Any ideas?

Thanks,
Jason
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The Robman
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Joined: 01 Aug 2003
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PostPosted: Tue Oct 14, 2003 7:39 am    Post subject: Reply with quote

The current spec calls for 1k resistors, and for laptop users it's recommended that you use a Schottky (1N5818) diode.
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johnsfine
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Joined: 10 Aug 2003
Posts: 4766
Location: Bedford, MA

PostPosted: Tue Oct 14, 2003 7:51 am    Post subject: Reply with quote

The JP1 hardware experts have changed their recomendation from 10K resistors to 1K. Did you not have lower resistors or were you working from old directions that specified 10K?

Without batteries in the remote, powering the eeprom might be intermittent. Lower resistors might make the eeprom able to reliably steal power from its signal lines, even if its power connection isn't right.

With batteries in the remote, the printer port voltage in the laptop is probably too low for best operation of JP1. Again, lower resistors make it more likely to work anyway despite the voltage mismatch.

It's a little surprising if the LED blinks due to the download attempt. The LED blinks just in response to the reset signal in the JP1 cable. That is the one most sensitive to voltage issues. If you had a voltage problem you would expect that LED blink to occur when you disconnect the cable instead of (the correct time) when you try a download.

If the LED really blinks at the right time, that seems to indicate you have the cable plugged in right and the voltage is good enough and the program is accessing the right printer port and doing so correctly and the reset signal is wired right.

I really don't think you fried anything. That pretty much leaves the possibility that you broke the connection of SCL or SDA within the JP1 cable, probably SCL because IR.EXE would probably give a different error message if the SDA diode weren't connected right.
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Lakee911



Joined: 14 Oct 2003
Posts: 6
Location: Columbus, Ohio, USA

PostPosted: Tue Oct 14, 2003 10:03 am    Post subject: Reply with quote

Thanks for the info! I'll try the 1K resistor tonight. The light blinked with the download, but it must have been the reset. We'll see if the resistors solve the problem. 1K isn't much, what if they were left out??

Thanks,
Jason
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The Robman
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PostPosted: Tue Oct 14, 2003 10:11 am    Post subject: Reply with quote

Which type of diode did you use? The 1N5818 is really needed for laptops.
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johnsfine
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Joined: 10 Aug 2003
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PostPosted: Tue Oct 14, 2003 10:27 am    Post subject: Reply with quote

Lakee911 wrote:
Thanks for the info! I'll try the 1K resistor tonight. The light blinked with the download, but it must have been the reset. We'll see if the resistors solve the problem. 1K isn't much, what if they were left out??


The LED blink is definitely caused by the reset signal and only the reset signal. When IR starts trying to download it pulls that low, which freezes the micro processor within the remote. When IR stops trying to download (succeed or fail) it tries to pull reset high. If that works, then the remote's micro reboots and the LED blinks. If the printer port's voltage is too low (quite common) then the reset signal won't go high enough to let the micro reboot and it remains frozen until you disconnect the cable. Since your printer port's voltage is high enough for reset to work right, it's a pretty safe bet that it's high enough for the less picky signals (SDA and SCL) to work right.

The other resistor is in the SCL signal. When reset is not pulled low, the micro in the remote tries to control the SCL signal. The 1K resistor is plenty high enough to ensure that it can drive the SCL signal either way regardless of the state of the printer port. When reset is low, the micro's SCL connection is tri-stated and a 1K resistor is low enough to allow the printer port to drive the SCL signal through the resistor.

If you left out the SCL resistor (I assume you mean shorted) then the micro in the remote would be fighting the printer port when it tries to control SCL (when reset is high).

The resistor in reset is less important, but probably increases the safety of the design when you plug the connector backwards or misaligned.

I still think it is more likely that your SCL connection broke after the time that JP1 worked, than that the resistors would make a difference. (Of course if you change the 10K to a 1K that will probably fix the broken connection, which is most likely one end of that resistor).


Last edited by johnsfine on Tue Oct 14, 2003 10:31 am; edited 1 time in total
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jamesgammel
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Joined: 03 Aug 2003
Posts: 394
Location: Gillette, Wyoming

PostPosted: Tue Oct 14, 2003 10:30 am    Post subject: Reply with quote

The reduction in resistance from 10K to 1K was mostly geared toward increasing reliability with using laptops, and some conventional PC's. We've known for some time that lappers are more fussy about this. We've also known for some time that lappers work more reliably with the schottky diode replacement. As I recall, the resistors are more for protection of the parallel port than the remote so much. Even tho 1K may not seem that much, I've seen cases where eveen 50 ohms make a dramatic difference. For the small cost of both the resistors and the diode replacement, is it really worth risking your lapper's possible demise? We can't stop you from noit using any resistors, but they have been recommended based on experience and testing. Since you're an electrical and computer engineering major, I'd assume that you know the purpose of resistors and diodes in circuits, so I won't go there. BUT, be advised that any modifications beyond what's been recommended is at your own risk, and beyond the wisdom and experience of the "hardware" experts in this group.
BTW, if you read all the docs in "interfaces" at JP-1 (yahoo) you should have seen that the "ultra" was designed to be more reliable, especially with lappers. When this project started, lappers were just coming around, and very expensive compared to typical desktops, not that desktops were exactly "cheap". If you're interested in the "history" of the interface designs, that information is available at yahoo as well.

Jim
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Lakee911



Joined: 14 Oct 2003
Posts: 6
Location: Columbus, Ohio, USA

PostPosted: Tue Oct 14, 2003 11:22 am    Post subject: Reply with quote

Thanks! I'll replace both resistors and the diode. But, hey isn't this all entirely at my own risk no matter what I use? Wink I'll let ya guys know tonight or tomorrow what happens.
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Lakee911



Joined: 14 Oct 2003
Posts: 6
Location: Columbus, Ohio, USA

PostPosted: Wed Oct 15, 2003 7:46 am    Post subject: Reply with quote

Well,
I replaced the resistors and once again had success! I was even able to check the intefact and it reprted that the check had succeded! After a little while though, it quit working, telling me it didn't get a response from the remote--I forget the actual response.
Unfortunetly, Radio Shack doesn't carry the Schottsky Diode, 1N5818, so I looked on Digikey and they've got it for $.39 + $5 handling + shipping. It'd almost be worth buying an ultra kit after getting that. Heh Any cheaper place thats recomended to get the diode? Is there any alternate part? What's the difference anyways?
Thanks for everyone's help!

Jason
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cdhixson



Joined: 04 Aug 2003
Posts: 48
Location: Charlotte, NC USA

PostPosted: Wed Oct 15, 2003 8:08 am    Post subject: Reply with quote

Look in the phone book for an electronics supply store. It looks like you go to Ohio State. There has to be a store somewhere near your campus.
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johnsfine
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Joined: 10 Aug 2003
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PostPosted: Wed Oct 15, 2003 8:24 am    Post subject: Reply with quote

I don't think a different diode would help.

When it once again worked once, was that with or without batteries?

I think the problem is in providing power to the eeprom. There is normally a capacitor on eeprom power inside the remote. That can make the eeprom sometimes work even when not correctly powered. It can depend on what you did right before trying to use JP1 (and how that affects the charge in that capacitor). The printer port might have been left in a state that charges the capacitor when you connect the cable before running IR. Later the printer port might be left in a state that discharges the capacitor before running IR.

When you work with batteries in the remote, the micro in the remote should charge that cap until IR pulls reset low (again the prior state of the printer port comes into play). The extra jumper in a JP1 cable (connecting two of the six pins together without connection to the printer port) is supposed to provide eeprom power from the remote's batteries. That could wired wrong or it may depend on another jumper inside the remote which is missing in some models.
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Filebug
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Joined: 21 Sep 2003
Posts: 74
Location: Mechanicsburg, PA

PostPosted: Wed Oct 15, 2003 3:29 pm    Post subject: Reply with quote

Send me an email with your name and address and I will send you the diode you need. jp1@filebug.com


-Tom
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Lakee911



Joined: 14 Oct 2003
Posts: 6
Location: Columbus, Ohio, USA

PostPosted: Sat Oct 18, 2003 12:38 pm    Post subject: Reply with quote

I've been thinking about the times that I've gotten the IR program to download data from the remote, and each time its when the parallel port hasn't been used in a while, and its been that the remote has been sitting for an extended period w/o batteries.
I got my new 15-1995 yesterday and I tried to get it to work with no success. I believe the problem is the diode. Sad Thanks to Tom though, I'll be able to get the correct one. I will take the interface and remote to work on Sunday though and see if it will work on a desktop (my only desktop at home is a dedicated Linux Server).
Thanks for everyone's help!

Jason
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Lakee911



Joined: 14 Oct 2003
Posts: 6
Location: Columbus, Ohio, USA

PostPosted: Sun Oct 19, 2003 4:50 pm    Post subject: Arg!!! Reply with quote

Well, I brought the interface and remote to work, but still not having any luck. Confused I think my problem lies in the fact that this machine is more laptop than desktop ... It's a gateway Profile 4. Mad (http://www.gateway.com/home/prod/hm_profile4x_proddetail.shtml) So, I'm going to await Tom's diode in the mail and build a new interface from scratch. If that doesn't work, I'll just buy an interface from him, and if that still doesn't work, the whole thing is going in the trash and I'll be back to my bunch of remotes. Evil or Very Mad

Jason
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Mark Pierson
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Joined: 03 Aug 2003
Posts: 3006
Location: Connecticut, USA

PostPosted: Sun Oct 19, 2003 5:10 pm    Post subject: Re: Arg!!! Reply with quote

Lakee911 wrote:
Well, I brought the interface and remote to work, but still not having any luck.

Have you double-checked all the connections to make sure there's no shorts, and everything is attached where it's supposed to be (including the end that connects to the remote)? The fact that it's not working on two different remotes and on two different PC's might be an indication of a problem. Also, what is your other remote (I only see mention of the 15-1995)?

Quote:
I'm going to await Tom's diode in the mail and build a new interface from scratch. If that doesn't work, I'll just buy an interface from him, and if that still doesn't work, the whole thing is going in the trash and I'll be back to my bunch of remotes.

Another option is the new USB interface. It's not supported by the currently available IR, but will be in the next release. I've built two myself (along with using a beta copy of IR with USB support) and probably won't be going back to the parallel interface. Wink
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