ESC and DAC for sending controlling from Arduino Nano

[Kikerumbo]

Hi there!

I'm trying to control an ESC from an Arduino Nano. The ESC has a potentiometer to control the speed of the motor.

This is the ESC: https://www.aliexpress.com/item/4000844153163.html?spm=a2g0s.9042311.0.0.9fbe4c4dRbSbhQ

I tried to hook a PWM output to the wiper of the potentiometer, but it doesn't work. It seems this ESC doesn't accept PWM, only a constant voltage. It seems that a NE555p timer controls the speed.

I bought a MCP4725 DAC and after hooking it up to the Arduino Nano, it outputs a steady voltage.

This is the one: Mcp4725 I2c Dac Breakout Module Development Board - Integrated Circuits - AliExpress

I programmed it to output 2.5V (middle of the range of the ESC after checking with the multimeter) and checked it with a multimeter. It outputs 2.37V. Then I connected the output of the DAC to the wire were the potentiometer wiper was connected to the ESC, but... it doesn't work.

Any advice would be appreciated.

Thanks!

[MarkT]

You need to replace the pot with a fixed resistor (of same value) and drive the wiper connection separately.

If you try to inject current to the wiper directly it'll disturb the error-sensing circuitry used to detect wiring faults in the pot. This safety feature is seen with motor controllers to prevent runaway motors if a wire breaks or shorts.

[Kikerumbo]

Thanks for the answer.

I forgot to tell that I left the potentiometer hooked (so I suppose it should still have that 100KOhm resistor) and only cut the wiper leg to connect it to the DAC.

Still doesn't work. Any other advice?

Thanks!

[slipstick]

Did you connect the 0V end of the pot to the DAC/Arduino GND?

Steve

[Kikerumbo]

No sir.

I connected the GND of the DAC to the GND of the 555 timer.

With your solution, the ESC is now full speed always. I checked the potentiometer and it has nearly 10V across the legs.

So I'm still not able to control it.

Thanks!

[flashko]

Why not bypass timer 555 and control directly?

[Kikerumbo]

Less things, less issues I suppose.

How can I do that? Where do I connect the DAC output in the ESC?

Thanks!

[flashko]

No, without a DAC. I have not used such a motor control board and I do not have much experience with motors. I assume that timer 555 is used as a PWM generator with adjustable duty cycle. Arduino has PWM pins. Maybe it would be good to increase the PWM frequency because the link says 'Frequency: 25KHz'.
https://arduinoinfo.mywikis.net/wiki/Arduino-PWM-Frequency
If the timer 555 runs at 5 volts, it will almost certainly happen by just turning off its output and instead connecting a pin to the PWM from the Arduino, but it may be best to use an optocoupler between the Arduino and the driver for safety.