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69 lines
3.6 KiB
Markdown
69 lines
3.6 KiB
Markdown
---
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title: Fortuna GPSmart BT
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layout: default
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created: 2009-02-02 19:07:10 +0100
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updated: 2009-03-31 11:53:41 +0200
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toc: false
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tags:
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- know-how
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- hardware
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- fortuna
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- gpsmart
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- gps
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---
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**Homepage:** [fortuna.com.tw](http://www.fortuna.com.tw/gpsmart.htm)
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<img src="{{ site.url }}/assets/gpsmart.jpg" height="300" alt="Fortuna GPSmart" />
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No fix since 2005-07-11
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=======================
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There is an error in the original firmware of the GPSmart that the device almost never get a fix since July, 11th 2005.
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The function to calculate the visible satellites is erroneus and gives wrong values since that date. So the device searches for satellites which are not visible.
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On [this page on eXpansys](http://www.expansys.com/ft.aspx?code=105113&thread=39), *johnr_61* writes that he patched the firmware with new ephemeris data
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so that everything works fine again. This patch should work until 2010-11-22.
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Update firmware
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===============
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Connect the device with the special cable. (Normal Mini-USB cables don't work since the devices actually provides only a standard serial interface
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which has to be converted to normal USB using the `PL2303`-IC from Prolific.)
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Use *FortunaSync* to establish the connection (*Link to Fortuna GPS*) and then use *SirfFlash* to upload the new firmware.
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<p><div class="noteimportant" markdown="1">
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There are some devices where the flashing doesn't work. If you try to establish a connection using *FortunaSync*, the device locks up.
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Some of these devices have a jumper `R30` on the PCB which should be shorted to get directly into flashing mode. Mine didn't have one
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but had a `J2` which might had the same effect, but it still didn't work. After some trying I found out that this device goes into
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the *SiRF Binary*-communication mode instead of the *NMEA*-mode the newer devices go into. So if you use *SirfDemo* to switch the
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device to NMEA-format, the firmware upgrade works until the device reboots itself. After that it's back into SiRF Binary mode and the upgrade fails.
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</div></p>
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Power cable
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===========
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You might have noticed that you can't power the GPSmart using a normal USB-to-MiniUSB cable. The backlight for the display can be switched
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on and off, but the display itself doesn't show anything. Since I had the same problem with my *HTC Universal*, I found a solution
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at [forum.xda-developers.com](http://forum.xda-developers.com/showthread.php?t=285768). According to [Wikipedia](http://en.wikipedia.org/wiki/Universal_Serial_Bus#USB_cables),
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the 4th pin is used for detection of *USB On-The-Go*, i.e. whether the other device provides power or not. Interestingly, the roles seem a bit mixed up here.
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According to Wikipedia, if pin #4 is grounded, the socket should provide power. Here it is that pin #4 has to be grounded for the device to accept power (for charging).
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After opening the GPSmart and bridging pins 4 and 5, I could successfully power the device via a normal USB-to-MiniUSB cable. After removing the bridge, the device powered off.
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My first idea for a solution was to use conductive lacquer coat to bridge the pins inside the MiniUSB plug. But then I remembered I had some adaptor:
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And lucky for me, the pins were already bridged in this thing. So I can now power my GPSmart using a normal USB extension cable and this adaptor.
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Sync cable
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==========
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The MiniUSB port on the GPSmart is not really a USB interface. The GPSmart has a serial interface and also uses the port for power.
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The FortunaSync cable uses a [FTDI FT232BM](http://www.ftdichip.com/FTProducts.htm#FT232BM) which also controls pin #4 (see above). This IC converts the serial signals to USB.
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