Duh moments, or how I ruined my cheap GPS receiver. - Page 1
Forum section: electronics / general

author: touchh
author_rank: Contributor
timestamp: March 09, 2012, 04:12:34 am
content: I've been working on some projects where I needed a GPS receiver, so I've been searching everywhere to find a source for cheap GPS receivers, and I found one!http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250899139844I don't think you can beat 11.95 for a GPS receiver with antenna and battery. I never had any intention of using the Bluetooth so I wanted to remove it and get the serial output directly from the GPS package.Just like I thought, it had a bluetooth module in it similar to thishttp://parts.digikey.com/1/parts/637501-module-spp-bluetooth-class-2-f2m03c2-101.htmlall I had to do was find the TX line and I could output the NEMA data right to my project without adding a bluetooth host and all that nonsense.So after I found out how to stop it from going to sleep (hold CTS low) since there was no active Bluetooth connection and got my NEMA data over serial successfully, I figured... Hmm I bet I could just remove that GPS Module all together, would save some power, because I was going to use the GPS receivers battery to power my project too. So I got out the hot-air gun and went about removing it, then tried to power it on....NOTHING... it didn't work anymore, so apparently the Bluetooth module is required for the unit to power on...hmm I would put it back on, but some of the pads toreGuess I'm going to order another one and have another go at it, this time just making the modifications to grab the serial before it gets to the Bluetooth module, but not removing the Bluetooth module.I'm still wondering why on earth it doesn't work without the Bluetooth module, i mean all the GPS processing and NEMA formatting is done by the GPS package located elsewhere. I noticed the Bluetooth module has outputs for 3.3 and 1.8v, I wonder if they used the Bluetooth modules voltage regulator for other stuff on the board?ARG! I really hate it when I have something working and botch it up, but I guess its all part of the learning process.Sorry for the rambling just thought I'd post this encase anyone ever was looking for a really cheap GPS receiver (and if you know of any others, please do tell me!)

author: 8086
author_rank: Super Contributor
timestamp: March 09, 2012, 04:31:36 am
content: I've been looking at this onehttp://uk.mouser.com/ProductDetail/Maestro-Wireless-Solutions/A1035-H/?qs=sGAEpiMZZMsa9w4dmI1JYEv5hDt7Ew5Y£15 but at least it's all documented etc

author: McMonster
author_rank: Frequent Contributor
timestamp: March 09, 2012, 08:45:08 am
content: Quote from: touchh on March 09, 2012, 04:12:34 amMaybe you accidentally unsoldered some of the pins/pads/balls of some important part there? Have you probed around to see if there's actually any power and activity in the circuit?

author: SeanB
author_rank: Super Contributor
timestamp: March 10, 2012, 09:58:21 am
content: I bought a similar one, that has a serial output via the micro USB connector ( the cable supplied with is only has power connected, used to charge the battery) so I took an old Nokia serial to USB cable and used the serial converter to supply both power and do the conversion ( never used the bluetooth and it does not need the battery if powered via USB) and it works well. The serial output works always ( left on running to a terminal window for 2 days and still was telling me the time and position in NMEA packets) and it is a small unit, with a patch antenna. All in a tiny box about the size of the bluetooth module you have, only thing I broke was the power switch ( bloody tiny thing on the side of the board and I tore it apart by accident opening it first time, so a small wire bridge in it's place ).The unit is a GTEK GSpace GS R23B.Just looked at it, and the little Fong Kong made HX-N3650A 850mAh battery inside is swelling, so I will be tearing it apart and neutralising it. Has not been charged or used for a year, and is swollen and squishy.