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cpqkgpsa
6 Posts |
 Posted - 26 déc. 2005 : 06:12:08
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Resetting Holux 236
I have recently opened my 236 unit to reset it and took some pictures for those who are interested.
Why? After synchronizing protocol and baud rate through the SiRFDemo utility my 236 would only send unrecognizable byte sequences over the Bluetooth connection. There was no way of resetting the protocol or baud rate with any software. I verified the raw output format was not in the Sirf binary protocol as some posts in this forum suggested.
The most likely reason for this behavior was that the Sync feature had set the Sirf chipset to a baud rate that exceeded the 236's builtin Bluetooth radio's capabilities. In this situation a software reset is probably only possible via a separately sold special USB cable. (A standard USB cable will not work).
Living in a place where obtaining such a cable would incur higher costs and a longer waiting time, I had to find another way to reset the unit.
After failed attempts to cause a reset by running down the internal buffer battery for several days (removed big battery), the best solution seemed to open the unit and physically reset the internal ram.
The biggest challenge was to find a way to open the case. After some trial and error (need strong finger nails), the unit opened from the side of the USB connector. You should be able to get a better understanding of the connecting mechanism from the pictures below.
Originally my intention was to unsolder one of the backup battery pins to reset the 236. However there is a faster way: the battery pins are very close together and after causing a short-circuit by connecting both pins for a fraction of a second, the unit was already reset! Although it would be preferable to cause a voltage loss by unsoldering the battery, causing a quick short-circuit should not damage the battery.
Hope the pictures are helpful to anybody in the same situation.
Cheers. Chris
Remember: Never use the "Synchronize Protocol & Baud Rate" menu option in SiRFDemo with the 236 connected via Bluetooth.
   
   
   
   
   
 
Update:
There is another common problem with the 236 which cannot be solved with the technique above. If your GPSlim236 has trouble to start or maintain a Bluetooth connection (Blue LED permanently OFF) then the following might help:
Open the case as described and press down the area indicated in the following picture, while you turn on the device. You might need to keep it pressed for a longer time if the blue light goes off again instead of blinking.
JayW has come up with this effective solution, which is however only a temorary remedy. He further suggests that soldering some PCB connections on the mainboard will permanently fix the problem.
There have also been suggestions that putting the unit into a refrigerator or near the aircondition can temporarily get the Bluetooth to life, however resoldering seems to be the first solution that would permanently fix the problem.
Remember that any surgery you perform on the 236 will most likely void your warranty. So if you still have warranty I would recommend to return the device and describe the erratic error. Make sure the 236 is tested over a longer time if they cannot immediately reproduce the problem, as some users stated they have been returned their defective unit as "functioning" since it would work flawlessly when tested by the seller.
Have a look at this thread for more information:
http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=64581#389452
Good Luck |
Edited by - cpqkgpsa on 07 sept. 2006 09:53:33
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paulkbiba
USA
5038 Posts |
Posted - 26 déc. 2005 : 06:29:03
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Hey, Thanks! Fascinating!
Moderator
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gpspassion
87879 Posts |
Posted - 26 déc. 2005 : 11:06:51
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Indeeed, but that old "dsynching problem" that plagued the first GR-230's in 2003 should be gone, my 236 doesn't have that problem, will have to check PN and SN numbers.
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cbmx6
United Kingdom
2 Posts |
Posted - 29 déc. 2005 : 00:26:30
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Thank you very much Chris for posting that, especially with the pictures as it came in very handy for a reset I had to do today.
My own woes came from playing about with SiRFDemo and putting it into a power save mode it refused to come out of. No amount of serial port/bluetooth antics would get it to talk. Luckily a reset did the trick.
In my case a momentary short wasn't enough - I needed to short for a full second to get it to clear the ram. (Even so it still seems less invasive than a soldering iron.)
For future readers I would also say make sure you don't lose the power switch which easily falls out.
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cpqkgpsa
6 Posts |
Posted - 29 déc. 2005 : 01:59:07
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Hi cbmx6:
I have had some trouble with the trickle power mode myself in the past, but was able to resolve it without opening the receiver. Here is my clue to what happens and why the unit appears to be non-responsive:
This is what the SiRF Binary Protocol Specifivation says about power save mode:
quote:
Computation of Duty Cycle and On-Time
The Duty Cycle is the desired time to be spent tracking. The On-Time is the duration of each tracking period (range is 200 - 900 msec). To calculate the TricklePower update rate as a function of Duty Cycle and On Time, use the following formula:
Update Rate = On-Time (in sec)/Duty Cycle
From my experiments it seems that between the intervals specified when switching to power save mode, the receiver actually shuts off completely and will not even process commands sent to it.
So in an extreme case when the receiver will only turn on every xx seconds, the chance of hitting an active period to send a reset is not very high.
So the best guess before opening the case would be to do some mouse acrobatics and try to switch back to continuous power mode in SiRFDemo until it works - or write a small utility program to do the job for you.
Chris
#36828;#22312;#27888;#23665; |
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cbmx6
United Kingdom
2 Posts |
Posted - 29 déc. 2005 : 18:13:56
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Interesting, that certainly explains it. I didn't pay too much attention to the time values. The first "on time", after power on, was always too short to be able to get a bluetooth connection up. I've filed this under "learning experiences".
On the plus side, opening the case allowed me to darken the blue led with some tape.  |
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coyotebush
USA
28 Posts |
Posted - 31 déc. 2005 : 11:48:23
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Many thanks for the information! I got my "dead" unit running in just a couple minutes.
I figured it was a baud rate mismatch between the Bluetooth module and the Sirf chip. I was getting ready to order the serial cable which would hopefully allow me to match the baudrate.
- John Morris
Menlo Park, CA
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cyberdude
8 Posts |
Posted - 14 janv. 2006 : 14:58:10
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Does this reset the receiver back to factory settings?
I can no longer connect to the assigned com port. I have paired the receiver to my PPC (i-Mate K-Jam running WM5) on com 7 but none of my GPS apps can see the receiver or receive any data from it and doing a scan shows nothing on com7.
I tried the reset discussed above but it didn't solve my problem. My BT blue light flashes and the fact that I can pair it with my device must nean that the receive is transmitting. It's not my PPC either as I have tried on my partner's and it doesn't work either. |
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cyberdude
8 Posts |
Posted - 14 janv. 2006 : 15:10:44
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| OK, I got it working. I had to short the terminals for about 3 seconds. But it's all ok now. Thanks for this thread cpqkgpsa. I thought I was doomed with a dead receiver. |
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Sallykil
Canada
6 Posts |
Posted - 15 janv. 2006 : 19:30:03
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I was thinking of buying the Holux 236, but now you all have me thinking it is glitchy. I don't think I am comfortable popping it open and attempting an ad hoc short circuiting for a reset. Should i get the special USB cable when I order it? Sound like they need a reset pretty often. Any other recommended Bluetooth receivers that would be as sensitive?
SallyK |
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Marvin Hlavac
Canada
6843 Posts |
Posted - 15 janv. 2006 : 20:54:46
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SallyK, I have had GPSlim236 for several months. I use it on almost a daily bases, up to 12 hours a day. I have had no problems, and at this time I don't think there is yet another GPS receiver out there which would meet my personal needs better than this one. So, if something should ever happen to it I would not hesitate to buy another GPSlim236 (unless something else comes on the market in the future which cathes my interest ;-)
Marvin Hlavac ~~~ To see my recent location click here :-)
iGkeys | iG Customization | S&Tkeys | ARkeys | S&T + AR Tips & Tricks |
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cyberdude
8 Posts |
Posted - 16 janv. 2006 : 13:36:37
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quote:
Originally posted by Sallykil
I was thinking of buying the Holux 236, but now you all have me thinking it is glitchy. I don't think I am comfortable popping it open and attempting an ad hoc short circuiting for a reset. Should i get the special USB cable when I order it? Sound like they need a reset pretty often. Any other recommended Bluetooth receivers that would be as sensitive?
SallyK
It's a great receiver. Now that mine is reset, it works faultlessly and I'm very happey with it. The reason I needed to reset mine was, that I was messing around with it setting it into SIRF mode, etc. I don't have the usb data cable so was using some software on my PPC and doing it over BT. I only found out afterwards that the software had a bug and couldn't set it back to NMEA mode. With all the messing around I tried, I think I messed up the synchronisation of the protocaol and baud rate - hence the required reset.
Moral of the story - don't fix it if it ain't broke 
Go ahead and buy the receiver. Just use it out of the box and you'll be fine. If you are inclined to mess with it then get the data cable too. |
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Sallykil
Canada
6 Posts |
Posted - 20 janv. 2006 : 08:59:18
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Thank you, gentlemen. I will buy it, sounds like best thing out there in bluetooth GPS receiverland. At least I now know what to do when I completely foul up the little bugger with too much benighted instruction.
SallyK |
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komsan
12 Posts |
Posted - 21 févr. 2006 : 15:40:07
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Hi,
I also have a problem as Cyberdude.
"I can no longer connect to the assigned com port. I have paired the receiver to my PPC (i-Mate K-Jam running WM5) on com 7 but none of my GPS apps can see the receiver or receive any data from it and doing a scan shows nothing on com7."
My 236 does not work now with unknown reason. I have successfully opened the unit case by following above pics. Please clearly explain how to short circuit to reset it. What tools should I use? I did it but nothing happen, still the same.
Thank you |
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cyberdude
8 Posts |
Posted - 21 févr. 2006 : 15:51:14
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Make sure the receiver is switched off. Then with a thin metal object, I used a small screw driver, touch the two soldered contacts coming off the small backup battery (shown in the image above). Make sure you touch both contacts at the same time and hold it for a second. I had to hold mine for about 3 seconds but I would try with less first. The receiver should be reset after that.
Good luck. |
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komsan
12 Posts |
Posted - 21 févr. 2006 : 17:22:08
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Thank you Cyberdude for very fast reply
I did it as you described but still did not work.
My 236 is paired normally with BT PPC and SPP connected on Comport 8 correctly. Unfortunately, no data or anything has shown on GPS Status page all applications. It says " GPS Not found".
How do you know that the device is resetted after doing short circuit?
Mine, have to connect and running GPS application in order to see that GPS work or not, am I right?
I suspected that my unit is dead. very sad because I used perfectly for a month ago but when I used yesterday it just did not work.
Anyway, Thank you so much.
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Holux GPSlim 236 Reset HowTo + Pictures
