C-GPS is Hard or Soft Add-in?

Hi All
I’ve not understand C-GPS, is it a hard or Soft Add-in ? What are the diffrencies with GPS Chip integrated in Q2501B ?


It is both software and hardware.
Hardware to receive GPS signals and do some basic processing, then software that runs on the GSM module to do the heavier part of the processing.

To use it all, you’ll need to write quite a big chunk of code yourself though, unless Wavecom gets around to write something to simplify it all.

What I had expected:

  1. gps_init(specify serial port, and maybe some other parameters)
  2. either supply callback that is called every second or so with new GPS data, or that you could simply ask for new data whenever with a function.

What I have seen so far:
You need to specify and handle serial port yourself.
You need to open a serial flow and set it in data mode yourself.
You need to write callbacks that can use the serial flow to send processed data back to the GPS
You need to continually call a specific function that determines if the data received on the flow so far is enough to calculate a new position
You need to handle loading/saving data from flash yourself

In short, prepare for a lot of work… (that may be worth it if power is low and performance is good).

Hi tobias
Thank you very much for your reply
So I understand, that we must get the eRide Chip separatly. and intergate it with a wavecom module supporting C-GPS plug-in ?

I don’t know if you get it from wavecom (or their distributors) or if you can get a separate.

The C-GPS offer as stated above has a hardware element which is purchased via eRide distribution channel and a compatible Wavecom Wireless CPU pre-loaded with the Open AT C-GPS Plug-In (Q2686 and Q2687 today, WMP100 and others arriving in April this year).

Included in the offer is a comprehensive application note with fully working license and royalty free samples that mean you don’t have to write a single line of code to demonstrate SMS transmission of geolocation data using the NMEA frame format to a remote GSM terminal.

You can get the application note from your distributor, along with details of the eRide distribution channel and Wavecom has plans to open up the access of a growing library of application notes before the summer (this year).

More information is available here: http://www.wavecom.com/C-GPS and for registered customers, there is a higher level of content on the same page once you log in. Request access from your Wavecom sales account manager if you are a direct customer. If you’re sourcing through distribution channels, you’ll have to get the app note, user guide, tech specs and other details/support from your distributor as of today.

The major benefit of the C-GPS solution is that you can use it on multiple Wavecom Wireless CPU devices and reuse the design accross different devices as your needs evolve. GPS performance is also much improved over what Q2501 offered and the complete physical size is around 30% smaller and much more powerful with the new ARM946 core (up to 87MIPS!). You can also upgrade the GPS functionality independently of the Wireless CPU when new GPS features are launched by eRide i.e. A-GPS and not have to buy a new Wireless CPU. Other benefits are in their PR here:


As for power concerns, if you use the new VariSpeed function in the RTOS release for Q2686 and Q2687, you can dynamically ‘on-the-fly’ switch between normal (26MHz) and boost (104MHz) CPU clock speed modes - in the middle of your Open AT app without resetting (!) - to optimise power consumption and I’ve seen a nice live demo at 3GSM of this in a use case to decode a JPEG image arriving over I2C interface from a VGA camera in a third of the time using the boost mode for ~1 second. Nice :smiley: