Conflicting MT3329 GPS External Antenna Connection

rhydolabz mt3329 gps module

MT3329 GPS module from Rhydolabz

The MT3329 SoC from MediaTek is a low power- high gain GPS receiver. I bought one of this from RhydoLabz (Part number : GPS-2261, 5V TTL Serial). It has a patch antenna on top. I used the GPS for my VANET project. The GPS and other accompanying modules are installed into a small remote controlled rover which has a full metal housing. So the metallic enclosure of the rover prevents the GPS from receiving signals from satellites. Therefore I have to open the cover each time for the GPS to receive any signal. To solve this I decided to add an external antenna to the GPS. But when I checked the datasheet of the MT3329, it had no external antenna pin, but the MediaTek website was showing that the chip could be connected to an external antenna. Then I checked another datasheet of the same chip, and that one said an external antenna could be connected and showed the pin details. This lead me to total confusion.

minimal atmega328 pinout

MT3329 conflicting block diagrams

May be there are multiple functions for those pins. Whatever, after some close inspection of the module I bought, I found that it had a footprint for an SMA connector which had not used by the manufacturers. One of the datasheet I checked shows D+ on pin 6 and D- on the pin 7 which are the USB pins for direct USB connection. The other datasheet shows pin 6 as GND and pin 7 as EXANT. The module I bought had the SMA footprint connected to the pin 7 of the chip and the pin 6 was connected to the GND. Having found out the functions of the pins, I connected an external antenna to pin 7 of the MT3329 and it worked great.

MT3329 GPS module pcb pinout

MT3329 GPS module pinout


  1. Robokits MT3329 Module [PDF]
  2. FGPMMOPA6B GPS Module Datasheet [PDF]


Date published : 8:39 PM, 21-04-2015, Tuesday
Last updated : 11:44 AM, 01-04-2016, Friday


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