New Year Testing Wiren Board

When we released Wiren Board - a compact industrial computer with Wi-Fi, GPRS, GPS and NFC - many asked us if we checked it at extreme temperatures. Usually, we answered that all Wiren Board components were selected for the industrial range, and the already finished devices in the package should be tested.
But on the New Year, real miracles happen - and today we are publishing a report on the testing of Wiren Board with ice and flame. And the real Snow Maiden will help us in this!

They say: under the New Year, whatever you want ...

We will carry out tests on the performance of Wiren Board as is in the widest possible temperature range. Although all the components are selected in the industrial design, there may be problems with a purely circuit design. For example, the capacity of electrolytic capacitors drops more than twice when cooled to -50 ° C, which means that pulsations in the power supply circuits increase, and unstable operation is possible.
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How do we do this?

Preliminary experiments have shown that if you just put the board in the fridge, it will cool down too quickly and unevenly. For gradual cooling, we placed Wiren Board in a cardboard box. The board was fixed on racks and was blown on the side by a fan that was connected to the low-voltage load control terminals. A fan is needed to quickly equalize the temperature inside the box. External GPS and GSM antennas were also connected to the Wiren Board.

The processor in Wiren Board has a special temperature sensor that allows you to measure the temperature of the processor chip. To measure the external temperature, we connected our favorite external DS18B20 digital thermometer to Wiren Board via a 1-wire interface ( connection example in our wiki).



The Python script running on the board collected data (uptime, timestamp, temperatures, as well as a list of wifi networks, usb status, GPS coordinates, etc.), saved them to the device’s internal memory, and sent it via GPRS to the Internet. To receive data, we used the Loggly service:

And the unbearable heat is heavy

For heating, we gradually pumped hot air into the hole in the box using a regular hair dryer. The temperature inside the box was leveled by a fan.


At the 37th minute, the GPS signal was lost at an ambient temperature of 75 degrees (crystal 87 ° C). GPS re-captured the satellites for a short time after 3 minutes at 95 degrees. At the 42nd minute at 114 degrees (113 ° C crystal), the GSM / GPRS connection was lost. After another couple of minutes at 116 degrees, errors began when working with a USB hub. At a temperature of about 120 degrees, the core finally fell into the kernel panic.
Overheated Wiren Board board survived without loss, all systems continued to work without any problems after cooling.

Do not shiver from the cold

It was not possible to catch the harsh Russian winter in Moscow on New Year's Eve, so we had to freeze the Wiren Board in the refrigerator. No, of course, not in an ordinary refrigerator, but in a low-temperature freezer at the MIPT Biolab, which can cool to -80 ° C.




Measurements in the refrigerator began when the temperature of the board had dropped to 0 ° C. At the 19th minute at -50 ° C outside, the board stopped giving signs of life. After the reboot, the board, which had cooled down to -59 degrees by that time, worked for a few more minutes, until it turned off completely. Thawing, Wiren Board earned again.

Results

No matter how hard the Snow Maiden tried, she failed to freeze Wiren Board - our computer could withstand a drop in temperature to minus 50! He coped adequately with heating - the first failure (loss of satellites) occurred only at 75 ° C, and everything else continued to work up to 114 ° C.

New Year is knocking on the door! Open him soon

A few days later the New Year will come, and we, the company “Contactless devices”, have a whole bag of thanks and congratulations.

First of all, we are thankful to the beautiful model Anastasia Azorkina and the photographer Alexander Lotsmanov , who turned our report into a little fairy tale.
We also thank the MIPT laboratory “Nanoconstruction of membrane-protein complexes for monitoring cell physiology” for providing the freezer.

Finally, we thank you - our readers, Wiren Board users, all those who made comments and gave us advice. We walked alongside you all of 2013, listened to you, and tried very hard. It is you who are helping to develop Wiren Board, and we hope that our friendship will continue in the new year. We wish you to celebrate the New Year brightly and warmly, and in 2014 good luck and new achievements awaited you!

And now a gift: until January 15, we make a 10% discount in our store - just enter the code WB2014NY when placing an order.