GPS Logger VI – PCB Layout and Case


Progress has been made on the GPS Logger over the last month. A sutiable case for the project was purchased, components ordered from Mouser and the circuit board designed. Once the component footprints have been checked off the design will be sent to BatchPCB for manufacture.

PCB Artwork for the GPS Logger

Most of the component footprints have been used before and do not need checking. The microSD, miniUSB and some of the capacitor footprints need to be checked to ensure that they are solderable and that they physically fit with the other components. The ground plane on the bottom of the board is split into a power ground, supplying the battery charging circuit and buck regulator from USB, and a signal ground for the digital logic components. R7 bridges the two planes at a single point, minimising noise between the analog and digital parts. All signal lines were routed at 0.2036mm (8mil) and the majority of the power lines at 0.2454mm (10mil). The power line from USB to the battery charger was routed at 0.6108mm (24mil) to handle the higher currents of up to 1.2A. The board artwork can be downloaded by clicking on the image above or as GPS Logger – PCB Layout.zip (125 KB)

During PCB design, several changes were made to the schematic to improve routing and to fix errors. The final schematic is shown below (click for a PDF version).

GPS Logger Schematic Final Version

The Case

The case was purchased from Altronics before the batteries arrived. I was under the impression that the Li-Ion batteries were AA size and got a case with an inbuilt battery compartment.

GPS Logger Case

As shown in the pictures above, the case needed to have the battery compartment removed so that the Li-Ion batteries would fit properly. Once assembled it will be a tight fit, however the batteries will not move around much. The case also came with a belt clip for easy carrying and the GPS Receiver will be mounted with its antenna facing the front of the case.

Software

The software running on the GPS Logger needs to be modified to support the battery charging circuit, USB charge port detection and battery monitoring. This cannot be tested until the PCB has be manufactured and assembled.

The PC software has been started, allowing transforms between Latitude, Longitude and Altitude (LLA) from the GPS to Earth Fixed, Earth Centred coordinates (XYZ) for distance calculations. Using a previous library, all the coordinates, trips and waypoints are stored in a SQLite database. The software will be a windows GUI and allow for:

  • Merging and splitting of legs
  • Auto detection of waypoints when stopped
  • Trip calculations (distance, speed)
  • Export of KML
  • Visualisation of trips (without maps/imagery)

With any luck most of the GPS Logger will be completed over the next few weeks as I am looking forward to testing it.

, , , ,

  1. #1 by Shanmu on February 8, 2011 - 3:52 pm

    Hi Nada
    Can you provide me protel footprinf for Mini USB.
    In one of my project I need that one.

    Thanks Shanmu

(will not be published)