Incorrect power connection. Can fried Moteino be recovered

[stewart]

Hi

Just received some Moteino's for a project, never used them or any Arduino board before.

All working fine,  then without thought I connected the 8.5v battery power I am using to the pins marked VIN and GND on the FTDI connectors.  Not surprisingly that Moteino doesn't work any more

Is there any components that might have fried that I could replace or is it best to learn from the mistake and put it in the bin?

Thanks

Stewart

[Felix]

Applying up to 16v to VIN (MCP1703 LDO) should be OK. You're at half that so no problems.
This is only true for regular Moteinos that have the LDO, not a Moteino-8mhz, which can only take up to a max of 3.6v.

If you touched any other pins with 8v then who knows what was damaged, the MCU itself is spec-ed at 5V, the other components (radio, FLASH if any) at 3.3v.
Also there is no reverse polarity protection on VIN, so -8V on that would also not be good.

What kind of Moteino was it?

[stewart]

Hi

Its a regular Moteino with RFM69HCW module.  I was a bit careful about getting the Vin and GND correct.  Is there something I can test to check for damage other than getting no response form the FTDI.

Thanks

Stewart

[Felix]

Was the FTDI connected while you applied 8V to VIN?
If yes, then the FTDI is probably damaged. The VIN is directly connected to the FTDI's VIN pin, which is directly connected to your USB's 5V. The FTDI is not meant to power your project, it's only for programming the Moteino. Applying voltages through it can even damage your computer's USB.

[perky]

It could be worse, the 8.5V could potentially propagate onto the other pins on the FTDI connector, and that could raise 3.3V through the MCU's substrate diodes via its RX pin.

Mark.

[stewart]

I had programmed what was to be my remote Moteino using the USB FTDI interface.  Installed your Node example and it was working fine. 
I then wanted to test connection at a distance so unplugged it and "powered" it by connecting the battery 8.5v "+" to the pin marked VIN on the FTDI interface and "-" to GND on the same interface rather than using the pins on the side of the board.
The normal flashing LED in the Node example didn't show and the Node did not connect to the gateway.  Connecting it through the USB FTDI interface nothing showed on the serial monitor and any attempt to program failed.
I did reset the device but nothing changed.
The connections were made before battery power was connected so I didn't touch the wrong pin by mistake.

Thanks

Stewart

[Felix]

I regularly use 9V batteries for field testing of Moteinos, and just like you mentioned, I simply apply the 9V to VIN, and everything works great, every time.
Again - 9V, 12V and even more, applied to VIN, will never damage a Moteino. The MCP1703 regulator has a max limit of 16V. This is true for ALL Moteinos except the Moteino-8Mhz which has no regulator.

I did reset the device but nothing changed.

When you reset the device, it enters the bootloader and flashes the LED a few times. Did that happen?

Otherwise I cannot tell what really happened without having the unit in front of me to tell what parts are damaged. You are welcome to send it to me and I can take a brief look at it, if that is worth it for you.

[stewart]

If I reset by connecting GND to RST, the next time I connect the the power the LED flashes. 

When I then try and upload any sketches nothing happens.  The RX LED on the FTDI adapter flashes 3 times then flashes at intervals until the upload fails.  The LED on the Moteino doesn't light at all.

I live in the UK so return is not worth the cost and hassle, thanks for the offer though.

For the future, it should be OK to power the Moteino from the VIN and GND pins on the FTDI interface at up to 12v?

Thanks again for your help.

Stewart
PS having great fun with these devices.

[Felix]

If I reset by connecting GND to RST, the next time I connect the the power the LED flashes. 
When I then try and upload any sketches nothing happens.  The RX LED on the FTDI adapter flashes 3 times then flashes at intervals until the upload fails.  The LED on the Moteino doesn't light at all.

Something is damaged, either on the Moteino (more likely) or the FTDI Adapter (if this was any way involved when you applied 8V). Try the FTDI on another Moteino, so you know if that works. Conversely you could try another FTDIAdapter with the Moteino in question to see if that works.

For the future, it should be OK to power the Moteino from the VIN and GND pins on the FTDI interface at up to 12v?

Yes, as long as this is a genuine Moteino (got it from LowPowerLab), you can safely apply 12V to [VIN+GND] to power the Moteino on its own. Ensure correct polarity and a clean power supply that is not spiking above 16v for any reason. Moteino should not be connected to anything else when you apply 12V.

[stewart]

Hi
The FTDI adapter is working fine on the other 3 Moteino's I bought so I don't think there is any problem with it so I guess I have somehow blown the Moteino. 
I have been powering from 9v pp3 LiPo batteries I had lying around, they have a run voltage of about 8.4v but never more than 9v - and no spikes!
Thanks again for your help.
Stewart

[stewart]

Success Update

Fried another Moteino by connecting the FTDI interface when the Moteino was connected to a battery.  Seems to result in instant death.
Eventually got round to sticking a meter on the two dead devices and the voltage regulator was putting out less than 1v.  Bought some replacement MCP1703 regulators (£5 for 10 including postage) and after a quick YouTube lesson on de-soldering and soldering surface components, replaced the regulators.
Both devices are now working absolutely fine.  Clearly tough little beasts.
Stewart

[perky]

Hold on, VIN is connected to the battery and to the 5V output from the FTDI interface isn't it? That's not good, I don't think you should do that unless you remove the 5V pin from the FTDI connector. There's a possibility the battery voltage has found it's way onto other signals including 3.3V through the FTDI connector, that may well have blown the regulator which acted like a shunt and protected the rest of the circuit.

Mark.

[savan8192]

Success Update

Fried another Moteino by connecting the FTDI interface when the Moteino was connected to a battery.  Seems to result in instant death.
Eventually got round to sticking a meter on the two dead devices and the voltage regulator was putting out less than 1v.  Bought some replacement MCP1703 regulators (£5 for 10 including postage) and after a quick YouTube lesson on de-soldering and soldering surface components, replaced the regulators.
Both devices are now working absolutely fine.  Clearly tough little beasts.
Stewart

Hi Stewart,

Well done on finding this. Looks like I did the same thing and have the same issue. I also want to see if I can resurrect a moteino by doing the same?

I am trying to find which one is exactly voltage regulator. Can you help me locate it? I have looked at design files but isn't helping.

Thanks



Thanks

[TomWS]

The VR is the three legged device labeled HU6U.   

It's easy to remove.  With a soldering iron in one hand and a thin 'pry' tool, like an Xacto knife or something, heat up the side with one pin first, gently trying to lift the device on that side.  Don't use very much force or you could ruin the PCB.

Once the first leg is lifted, do the same for one of the other two.  It will lift easily now.  Finally, using tweezers or needle nose pliers, hold on to the lifted parts and heat the third leg.  Easy peasy...

[savan8192]

The VR is the three legged device labeled HU6U.   

It's easy to remove.  With a soldering iron in one hand and a thin 'pry' tool, like an Xacto knife or something, heat up the side with one pin first, gently trying to lift the device on that side.  Don't use very much force or you could ruin the PCB.

Once the first leg is lifted, do the same for one of the other two.  It will lift easily now.  Finally, using tweezers or needle nose pliers, hold on to the lifted parts and heat the third leg.  Easy peasy...

Hi TomWS, thank you for the clarification and the advice - sounds very useful.

I will attempt that soon.