Question GC+ Data Line Stuck at 3.3v

[Dustin Fisher]

Hey all, I have been looking around the forum for quite a while now looking for a solution but unfortunately, I haven't had any luck so far. I have been working on a modified version of the Gboy for the past couple of weeks and I just got around to installing my GC+ 2.0 and hooking controls yesterday. After I turned it on to verify that everything worked I noticed that I had no control over the Wii. I did a bit of digging to try and see what was going on and if I just simply crossed some wires somewhere but I did continuity tests and all seems to check out. In measuring the voltage on the GC+ I noticed that it was being held at 3.3v. I verified that it is not tied directly tied to 3.3v rail somewhere due to a short as well. I also took an oscilloscope to it to verify that no data was being transferred at all. I also noticed that this stays the same even if I disconnect the GC+ from the Wii. I just recently checked the voltage on all other pins and it seems just about all of them read 3.3v as well. I am not sure how the GC+ is laid out but it seems that these are all pull-up resistors. In measuring the resistance between them and 3.3v rail I get ~700 ohms. this is also true on the GC+ data line. Is it possible I got a bad/unprogrammed GC+? I got it from 4layertech.com and I know that everything is already supposed to have proper firmware on it. Is this a super common issue and I just missed a miracle forum somewhere? If it helps I am still running portablizemii. This trim of mine has been around a while and was done 4 years ago or so when that was state of the art XD. Any help would be great. Here are some photos I took of my wiring for you all as well

 

[Dustin Fisher]

Also, I wanted to mention that I checked the voltage at the via that's attached to the u10 chip and it measures at 3.15V

 

[jefflongo]

You are correct that there is a pull-up resistor array for the data lines for the controller. The GC controller protocol is open drain so the controller drives the line low for its communication. I doubt that you have a "bad" GC+, they test them before shipping them out. I would double check the P1 via to the GC+ connection with a multimeter, also make sure the GC+ is getting 3.3v and ground.

 

[Aurelio]

If you don't get any signal coming from the P1 via even if the GC+ is disconnected then the Wii is not sending anything. This usually happens when the U10 is not connected properly or damaged. Try replacing it

 

[Dustin Fisher]

Thanks for the response! I just tested to make sure I'm getting 3.3v on the GC+ and the connection between the GC+ data line and the P1 via is good and checks out.

 

[Dustin Fisher]

so, there should be a voltage on the p1 line even when the gc+ is not connected? I thought data communication was one way. I can verify that the p1 via is at 3.2v which is the same as my 3.3v line. I dont have access to an oscilloscope at the moment to check for any data that way but I would expect the voltage on the line to average lower than the 3.3v rail if data was being sent. if it is the U10 I can use the u10 emulation on the pms to fix it. wouldn't the gc+ data line also be less than the 3.3v line even when disconnected from data though? does it always try to send data or does it wait to see a signal from the wii?

 

[Dustin Fisher]

so, I just double-checked my u10 install, and all checks out. 3.3v and ground are not shorted on the chip and have continuity to their proper rails. on power up, it also gets appropriate voltage. the output is also not shorted anywhere. is there a threshold for the output of the signal? As I mentioned before it is at the 3.3v rail but that rail is only at 3.2v. I also verified again that there is continuity to the via under the board and it's getting the proper voltage from the u10 chip as well. Any other thoughts? I can't quite test the u10 emulation of the RVL PMS since I need to use the soldering equipment at my place of work to make changes.

 

[Stitches]

so, there should be a voltage on the p1 line even when the gc+ is not connected? I thought data communication was one way. I can verify that the p1 via is at 3.2v which is the same as my 3.3v line. I dont have access to an oscilloscope at the moment to check for any data that way but I would expect the voltage on the line to average lower than the 3.3v rail if data was being sent. if it is the U10 I can use the u10 emulation on the pms to fix it. wouldn't the gc+ data line also be less than the 3.3v line even when disconnected from data though? does it always try to send data or does it wait to see a signal from the wii?

IIRC it's a bi-directional data line

 

[Dustin Fisher]

Boy have I learned a lot over the past couple of days! I believe I have narrowed down exactly where the issue is but I still have a few questions. To back up a bit though, I decided to use a spare Gamecube controller that I had and that I knew worked to verify that the Wii was not accepting any inputs at all and that this issue is not related to the GC+. using this site https://simplecontrollers.bigcartel.com/gamecube-protocol I was able to find out that the data line is bi-directional confirming what Stitches said and that the controller doesn't report anything back unless it receives a signal from the Wii. so, I went to probe the P1 via on the Wii and there was absolutely nothing. I then probed all other controller port pins and none of them worked except for P2. P2 was the only one that had any data at all and I checked several times. I was able to confirm the GC+ works by wiring it to P2 and seeing that the signal changed. Also, for anyone reading this down the line using a multimeter to see if there is data going to and from the Wii kinda works but it's not the best. with everything working I was able to observe a .1v decrease below the 3.3v line due to data transmission whereas it was just at the 3.3v line when not working but this can vary depending on what's being transmitted. but if you don't have an oscilloscope this could work to help diagnose. anyways, I believe the reason this has happened is due to me messing around with this trim a few years ago trying to hook up all controller ports in a different case. It is possible I damaged P1 but I'm not sure why 3 and 4 are also broken. Is it at all possible to have the wii take primary input from P2? I have confirmed that no matter where I probe on the P1 line that it's not getting any signal anywhere; including both sides of the via and down the line as far as I can trace it. Thanks for everyone's help so far

EDIT: oh! I forgot to mention that I tried using the U10 emulation on the RVL PMS and it seemed to work exactly the same as before. I'm very confident now that is not the issue