Controllino MEGA – Irregular Resets

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Hello,

I’m using a Controllino MEGA in a HeatingControl Szenario with several Pumps, Vents and a lot of OneWire Temp-Sensors.

Except of the Temp-Sensors everything is controlled by 24V (Inputs/Outputs) or 230V (Relay Block – Block A is not used so far.

The 20 OneWire Sensors (DS18B20) are connected in 5 Buses to the PinHeaders (Arduino Pins 10,16,17,20,21), as their signal is 5V based !

Since the installation there were irregular Resets of the Controllino.

After a lot of research I found out that it was a combination between two issues:

• • The /Reset-Pin (Pin 11 on X1 and X2) has only 3,7 V ! It should be pulled up to 5 V – isn’t it ?

    I measured the Short-current (ResetPin against GND) of 0,6 mA – which means there is a Pullup of about 7k present !

    Is there any other circuit connected to the reset pin, which can bring the voltage down ?

 

 

• • There are some interferences coming from the 1-Wire buses – These finally triggered the reset from time to time.

 

After knowing all that, I pushed the /Reset with another external 1k Resistor to 5V, and the Resets have gone !

But this is not the solution ! Any ideas ?

Frank

[Jarda]

Dear Frank,

Please use the solution with External 1 kOhm resistor.

There is no risk of damage of the CONTROLLINO.

BR

Jarda

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Hi Jarda,

thanks for your reply, but could you please explain, how this could be ?

What kind of circuit is in there that cause this voltage drop – or is it defective ?

On my other Units (MINI and MAXI Automation) I have full 5V in the /RESET Pin !

Unfortunately I don’t have another MEGA here to check that …

Frank

[Jarda]

Dear Frank,

your CONTROLLINO is not destroyed and this is behaviour of the MEGA variant only due to the connection of more ICs to /Reset line (higher current consumption via pull-up).

With this configuration we have passed EMC imunity test, but we are going to improve it in the next production lot.

Thank you for your feedback.

Regards

Jarda