Help with USB pins? - Page 1
Forum section: electronics / beginners

author: andrewukr6
author_rank: Newbie
timestamp: August 18, 2016, 11:56:00 am
content: Hi, I am trying to wire an LED 3v to a spliced micro USB cable. The developer sent me this picture saying wire to S2 and 5.I cannot get it to work, I think possibly its because my USB donor cable only uses 4 pins, but upon internet research it seems the 5th is often linked to the ground anyway.... Anyone with more knoweldge help? (on a sidenote this is for the Yi 4k action camera, I wanted a leaded LED status light to show when it's recording, the developer built this into firmware for me to test).Pics:*use S2 for + and 5 for - to LED*

author: jeroen79
author_rank: Frequent Contributor
timestamp: August 18, 2016, 12:24:19 pm
content: What exactly are you trying to accomplish?Tx and Rx aren't part of USB.And what is U14? Is it an IC?

author: Brumby
author_rank: Unknown
timestamp: August 18, 2016, 12:32:53 pm
content: Yes ... something isn't making sense here.

author: andrewukr6
author_rank: Newbie
timestamp: August 18, 2016, 12:49:32 pm
content: thanks for the replies, the diagram is the one he sent me asking to connect LED to pin S2 and pin 5 (gnd). The idea was when the camera is set to record, it would output 3v to the usb. However I am not seeing any voltage above 0.3v on any pins. I wondered if maybe he was using the 5th pin oin the micro side that doesnt appear on the standard usb plug....

author: jeroen79
author_rank: Frequent Contributor
timestamp: August 18, 2016, 01:27:42 pm
content: Surely the person who sent you this should be able to tell you more.Are you sure that this is supposed to be an external mod?May be you should build the LED into the camera.

author: andrewukr6
author_rank: Newbie
timestamp: August 18, 2016, 02:09:45 pm
content: Quote from: jeroen79 on August 18, 2016, 01:27:42 pmThe camera has a built in LED light, however as a skydiver I can't see if it's recording when its on my head! A company does an LED leaded status light for gorpo for £100, I contacted the software dfeveloper of the camera and asked if it was posible to output 3v through the micro USB, and he said yes, and built it into a firmware test... however I cannot see 3v on any of the normal 4 usb pins. Basically I came here to find out if there are variants in USB leads, with 4 or 5 wires in as maybe I'm looking for 3v on a wire that isn't in the cable im using (maybe s2?). But I will try to get more info from the software dev, however he's chinese so communication isn't perfect :-)

author: jeroen79
author_rank: Frequent Contributor
timestamp: August 18, 2016, 02:30:37 pm
content: Apparently 11 pin microUSB does exist and it has extra pins for video, audio and data.You'll need a cable for that.For now you could try probing the pins with a thin needle to verify the voltage.

author: edy
author_rank: Super Contributor
timestamp: August 18, 2016, 06:19:22 pm
content: I have the SJCAM SJ4000 and it also has a micro-USB for either power/charging, data transfer (mounts the SD Card as a drive), or to be used as a USB camera on the computer.But..... in some modes it also will allow you to send video out on the USB if you make a special cable. You can see a video of it below. It will send out a composite signal. So it sounds as if your micro USB port on your camera may have 11 pins, you'll have to look carefully and see if they are there inside your microUSB port. If they are, then you need to buy the special 11-pin microUSB cable to access those contacts externally and get to your LED signal.Apparently, the 11-pin micro USB is called an "MHL" cable and usually is used to go from a phone that supports it, to an HDMI to play on a big TV. That way, they don't have to insert another port on your phone (micro HDMI).... instead they use the same port for both micro USB functions and with the MHL cable you can hook it up to HDMI on your TV.You can find info on MHL here:https://en.wikipedia.org/wiki/Mobile_High-Definition_Link