Basic idea: Convert drive-by-cable driven HVAC system to drive-by-wire system, specifically for the heater valve.
More indepth: Replaced cable actuated heater valve with electronically controlled valve that has a feedback potentiometer in it, and the motor polarity determines whether to close or open the valve.
I used a power supply to bench test everything and it all worked out. However, the Pro Mini was getting pretty hot and the HBridge eventually fried. Both showed powering up but the Pro Mini eventually stopped connecting to anything.
The on-board regulator should work with 12V input, eventually gets hot and shuts down Vcc when too hot. But car voltage can be much higher, with spikes over 50V, so that a more rugged regulator to 5V is recommended.
Please connect the battery - directly to the motor driver Gnd, don't run the motor current over the board.
A very real danger is that the obsolete tutorials on the Arduino site and others misleadingly imply that the largely ornamental "barrel jack" and "Vin" connections to the on-board regulator allow a usable source of 5 V power. This is absolutely not the case. It is essentially only for demonstration use of the bare board back in the very beginning of the Arduino project when "9V" transformer-rectifier-capacitor power packs were common and this was a practical way to power a lone Arduino board for initial demonstration purposes. And even then it was limited because an unloaded 9 V transformer-rectifier-capacitor supply would generally provide over 12 V which the regulator could barely handle.
If you are asking this question, it is highly likely that you will wish to connect something else. In which case, the answer is regulated 5 V.
This is because the on-board regulator is essentially capable of powering only the microcontroller itself and no more than a couple of indicator LEDs. The on-board regulator might be able to power a few other things if it had a heatsink, but on the (older) Arduinos, it does not.
Powering via the "barrel jack" or "Vin" connections is asking for trouble. The "5V" pin is not by any means an output pin, if anything a "reference" pin but most certainly the preferred pin to which to supply a regulated 5 V.
A practical power supply for the Nano (or UNO, Pro Mini, Leonardo etc.) is a "phone charger" with a USB output connector for 5 V, generally up to a couple of Amps though you can not feed more than 500 mA through the USB connection.
If you want to power it from 12 V or a car system, you need a 5 V switchmode "buck" regulator to supply the 5 V.
Unlike most other DC motor driver modules, this module has a single VCC for both control logic and motor driver circuits as your drawing shows. By default, all control inputs are tied to VCC through 10K pull-up resistors; hence, the motor outputs are in “off” state (L-L). Obviously, we can run the module from a 3-V DC supply for 3-V DC motors and from 5 V for 5-V DC motors. But there’s a hidden danger with 12-V DC motors (12-V VCC). Because the control logic inputs are tied to VCC rail, it will damage the 5-V I/O microcontroller if used to control the module. The L9110 has a large current driving capability, each channel through 750 ~ 800mA of continuous current, peak current capability up to 1.5 How much power do your servos require. A few things we need to assume, your bridge and micro are both fried. I would suggest you start with a different bridge that has an independent motor supply input. I would use a SEPIC converter as my voltage converter outputting 8 volts into the raw input. Reason some cars have a 6V cold crank specification some are less. I would protest the input of the SEPIC converter with a transient device and polarity protection in case somebody jumps the battery in reverse. Your pot connection is fine. This will protect the devices and keep everything in operating range even during most faults.
I should state that, I'm not an electrical engineer by any means, and this is my first project.
So, sounds like I had a few fixes that needed to be put into place:
Problem: GND pin of Hbridge is connected to GND on Mini.
Solution: GND pin of Hbridge to chassis GND or battery neg.
Problem: Ignition 12v from Battery is used to directly power both Hbridge and Mini
Solution: Wire up a voltage regulator between 12v and Hbridge & Mini
Can I tie the two Pots + signals together on one VCC?
Can I do the same with their GNDs?
DrDiettrich:
The pots should use the Arduino Vcc and Gnd. You can use 3-wire (servo, JST...) cable for each and connect to the Arduino board.
I guess my question is, do the Pots have to go to separate VCC and GND pins... or can they be joined together?
I'm assuming they can be joined together, since they are just receiving voltage and the signal wire going to the analog pins is what is carrying the important piece -- but want to make sure since I'm a bit of a muppet with these things.
The Pro Mini is the right board for the job as long as you use a proper regulator module to provide the 5 V power, but you need to mount it on some "stripboard" in order to have multiple connection points to ground and Vcc/
Aliexpress example
If the pots are in different locations then they should have separate connections. It makes sense to have Vcc and Gnd lines in parallel for each sensor, for best immunity against external or internal noise.
