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Project logs / Location Based Development Board
Courtesy of Dangerous Prototypes Dirty PCB service, I have been able to put together and complete the testing of the first prototype of my very own location based development board. Here's a bit of a glamour shot below.
So lets talk about what you’re looking at. The board is a 4 layer PCB of dimensions 50 x 68 mm. The populated board has a maximum thickness of 9 mm. I considered using a 2 layer board, but the ground planes would not have been large enough and the substrate was too thick for the micro strip trace to the antenna to be of a realistic width. The microcontroller is running an Arduino Bootloader and the board is pictured on 7mm standoffs that are attached using M2 screws. Below is a photo of the assembled device and an overview of the hardware on board.
On the topside of the PCB, Image attached, working top to bottom, the device consists of:
- Penta-band GPRS/GSM/EDGE/HSPA/CDMA Antenna
Antenna Matching Circuit
Micro SIM Card Holder
uBlox SARA-G350 GSM/GPRS Module (2.5G)
Netwok Status Indication LED
Standard Arduino LED
Micro SD Card Holder
uBlox CAM-M8Q GPS Module & Embedded Antenna
Mini-B USB Connector
F234XD USB-UART Controller
Voltage Regulation
Li-Po Battery Charging Controller via USB
JST Connector for Battery
On the bottom of the PCB, Image attached, working top to bottom, the device consists of:
- Additional Voltage Regulation
3x Expansion Ports that use FFC Ribbon Cables
ATMega2560AU Microcontroller
Logic Level Converter
The board acts like any other Arduino, building upon that easy to use and powerful framework that is particularly inviting for new users. Too commonly I see pictures of people who have created complex circuits involving GPS Modules, SD Cards or GPRS Modules ect and they all have one thing in common. They are either very messy and fragile with wires running everywhere, often consisting of large areas of breadboard, and they are bulky. An Arduino Mega and a shield or two in terms of electronics is gigantic, far from pocket sized. This to me feels pretty nifty in terms of size, and what you can do with it.
So with the overview complete, I thought I’d move onto some of the things I have been able to undertake with the device. The firmware I have running on the device currently takes in the GPS data from the serial UART, processes it on board, establishes a GPRS connection, and then carries out a GET Request over HTTP to place that GPRMC data into a mySQL database using a PHP script. I can then log onto an online application and view the location of the device in real time. Furthermore this device will carry out this task anywhere in the world with a cellular connection. This is a much more attractive method than Wi-Fi or Bluetooth where range becomes an issue. The location is displayed using google maps, as shown in the application screenshot below. The device runs off a data only M2M Sim that costa about 45p a month prepaid for 2Mb of data which is plenty for just GPS data.
So that's what I've been able to do so far and really I was just looking to get a little feedback from the community on the project. When I feel it's ready, I'd love to release all the design files. I've got a few things in the works using the expansion boards and so I'll post that when it's done but I'm really looking forward to getting a feel for what you think of the project.
Thanks.