Development of a GPS tracker from scratch and 512 months warranty

Greetings! For more than five years we have been developing various devices for monitoring vehicles, this article will talk about the whole process - from the idea and the breadboard to the final stage of production in serial lots. To whom it is interesting - I ask a tackle (many pictures).

Development

We are one of those who do everything ourselves. Let it be a long time, albeit expensive, but in such cases we remove all the flaws until the moment of release, and no one needs to be blamed for failure. The main tasks that were involved in the development of the new device were reliability, the availability of an accelerometer, working with any devices using rs-232, as well as the convenience and simplicity of installation for the end user (bought, installed, used). No auto electricians or other installers.

GSM

Due to interruptions in the supply of Telita to Ukraine, the choice was made in favor of the Quectel M12 module. The module is quite famous and replaced the M10 module. It has the same form factor as Telit (SMT), is convenient in troubleshooting, because all its outputs are displayed on the sides (no BGA). For the most part, the module has exactly the same (or very close) characteristics to Telit. It is worth noting that in the Ukrainian market almost all modules have the same functionality with the main differences only in the development environment, and here everyone chooses what he knows best and what is more convenient to "write". I would like to mention about the M12 chip in the form of OpenCPU , which greatly reduces the entire development process of the finished device, and is extremely easy to learn.

GPS

Well, there’s an interesting story here. Initially, everything was developed for the chip that was used in the last Uranus 625r device. But at the time of the order, the Chinese said that this chip was discontinued, and they are 100% sure that the new chip (of their own production) will satisfy us a little less than completely. During the negotiations, pin-to-pin compatibility was agreed (and this is rx, tx, reset (here special attention will be discussed below), land), this moment was raised several times in correspondence and oral negotiations. I was very pleased with the availability of the new Sirf IV and support for loading the ephemeris for the operation of a-gps mode. Looking ahead, I can say that if you remove a fairly large amount of marriage (about 10%, which, thank God, can be eliminated at the stage of assembly of devices), the quality of the receiver itself is quite excellent.

Assembly number zero

Because etching the board for such a device is not very convenient, it was decided to use a breadboard for the initial revision


Here is such an “ideal” trace:


A small embarrassment in development:


Well, the main employees close-up:


After debugging all the main points, we switched to human wiring and preparing for production. The result is lower (both sides for comparison):


After agreeing all the specifications, the board was put into production and 8 weeks were spent on the search / purchase of all spare parts for the manufacture of the first batch. After about two months, the first 10 devices were received:

As usual

After receiving the first samples, usually the most interesting part begins - this is when everything seems to be correct and it seems to have been tested for a long time, but nothing works. Or it works, but not like that. It just doesn’t work and it’s like nothing can be changed.
And so it happened. The “magic” GPS modules that arrived just “were silent”. We put the old ones - everything works, we call out new ones - it should work, but "the skis do not go." The reason for this is the use of reseta at the first start, when the module accesses the stack for the first time. The Chinese, with their inherent surprise, said that “it was necessary to warn” and sent a manual on how to return everything to its place. After raising all correspondence and sending them, they simply promised that this would not happen again. A curtain.

TTX finished device

- start in 2 seconds, AGPS
- sirf IV (the ability to replace with glonass for the Russian Federation options)
- memory for 250,000 points
- adaptive mode
- shock / vibration sensor (accelerometer)
- beacon mode
- remote control and tariff plans through direct USSD commands
- work without a server via SMS
- and many more are described in more detail here

Bonuses

The retail cost of the device at the moment is 180 cu Dealer prices at certain volumes fall to 110 cu On our service, the subscription fee until the end of 2013 is completely absent when connecting any number of devices.
As usual, the warranty is 512 months from the date of purchase of the device (does not apply to the battery).