Adrare WROTE:@moderator,
Hello,
in your repply you wrote that grounds are commoned; on the board MD30C R2 I just received, it seems (according to my ohmmeter) that there is a diode between the minus power pin and the Gnd pin of the ext PWM connector (JP6 being on ext position); the cathode seems to be on the power side, anode on the PWM connector side. So my questions are:
1/ how is the Gnd interconnection made, would you have a sketch of it ?
2/ I'd like to put a 0.05R resistor in order to measure the current in the motor and prevent from overload
; this resistor should be seen by an analog port of the MCU (PIC18F), referenced to ground. Where do you suggest I should place it in the power circuit ? I'm confused with this diode between the 2 Ground...
Thanks a lot in advance,
Gerard
Hi Adrare,
The common ground is referring to:
- GND on JP3 which is the external PWM and DIR control pin.
- GND of power input (if the polarity is correct as there is polarity protection MOSFET on board)
The rest of interface including EXT POT (JP5) where an external potentiometer is connected are not common grounded.
With shunt resistor method and common ground is needed to measure from external microcontroller, you can put the resistor at the power terminal, negative terminal :
JP1 (POWER) Negative terminal ------ 0.05R resistor ------ Negative terminal of battery (Ground)
Where the microcontroller GND should be connected to Negative terminal of battery too.