Meteobridge NANO

All about the standard Meteobridge devices based on mobile routers from TP-Link, D-Link, ASUS

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Meteobridge NANO

Post by admin » Tue Jun 12, 2018 5:58 pm

With the introduction of the remarkable stamp sized VoCore computing platforms about two years ago the idea grew to build a Meteobridge as a plug-in module for Davis consoles. But things turned out to be a bit difficult that days... My prototypes with the VoCore1 in 2016 fitted physically but needed too much voltage for a console plugin and did not provide the necessary number of serial ports and lacked stability on WiFi operation. So I paused the idea. VoCore2 - which was released in 2017 - finally had all the needed features but also started with severe WiFi issues caused by the poor driver support for the MT7628 SOC, which has been keeping me busy until early this year. Finally, all that was solved back in February and I started to build a complete Meteobridge as a Davis console plugin module. Development is done and we call it the NANO. :D

nano-free-400.jpg
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You can find more information here: http://meteobridge.com/wiki/index.php/Meteobridge_NANO

We have prototypes running fine and will start a first large production batch end of June. When things go straight units will be available for purchase in August.

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Re: Meteobridge NANO

Post by admin » Wed Jun 13, 2018 11:02 pm

As I was asked I would like to add some information about power demand and battery use.

Power Demand:
A Davis Vue console peaks at 250 mA when equipped with a NANO. This goes down to 150 mA when NANO does not actively operate the WiFi.
When LCD backlight is switched on at the console it draws additional 100 mA.
The Davis power plug is rated 300 mA. That is OK for operating the NANO, but when you switch on LCD backlight on the console and NANO is doing WiFi traffic the setup draws too much juice from the Davis power plug and Voltage will drop to a level where the NANO reboots.
Therefore, it is recommended to use a stronger power plug when operating the console with a NANO. We are currently sourcing power plugs that can do that and will add it to the product bundle.

Batteries:
Batteries in the console only step in, when voltage of the power plug is going beyond a certain level, which also includes the situation when no power plug is connected at all. When operating the NANO with the original Davis power plug, batteries will add a few mA when WiFi is operating. It is just in the range of 1-2 mA but over time this might empty your batteries (within a couple of months). When you go with the stronger power plug, voltage will stay fine even when NANO is doing more heavy load and batteries will not be eaten up. Batteries in the Vue console typically have a capacity of 8.000 mAh (type C batteries). Assuming an average demand of 150 mA this will result to about two days of battery operation. As you see, running the setup on batteries only is not an option.

I did not test with Pro2 Console and Envoy but I assume numbers will be similar.

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Re: Meteobridge NANO

Post by admin » Thu Jun 14, 2018 7:12 pm

As average power consumed by a NANO-equipped console is well in specs of the Davis power plug I made some experiments with adding a larger capacitor. Idea is to get the spikes compensated and to check this I monitored the voltage reaching the NANO computing module with my scope.

On the left picture you see the voltage the NANO receives from a console powered by the Davis power plug. When WiFi starts operation the voltage drops down to 3.1 V on certain spikes which is dramatically below the 3.6V needed for stable operation of the NANO's computing module. No wonder that it reboots being punched so badly.

The picture on the right shows the same spike situation with a 1000uF capacitor applied. As you can see voltage does stay above 3.8V which is a huge improvement and also gives some headroom to the recommended 3.6V minimum level.

TEK.png
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The result of this finding is, that I think a Davis power plug replacement can be avoided by adding a suitable large capacitor to the NANO. Looks like I will have to free up the PCB a bit to find some room for a large SMD capacitor and by that dropping the need for a new power plug. :D

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