ALSO - I recall reading a thread on here about connecting directly to pin 2 of the 555 chip with the Arduino PWM output, but can find the thread now...
would this possibly work instead?
If you want to do that you need a CD4050 TTL to CMOS converter chip to convert the 5V PWM to 12V PWM.
but why does it say 0-5V on the pot input socket?
Actually I didn't see that until you mentioned it. I suppose you could try putting a meter across the pot to measure the voltage to see if it really is 0 to 5V. If it is , you could probably use pwm with an RC LPF circuit to smooth the voltage out. (4.7 k ohm/4.7 uF)
I don't know if it has occurred to you , but if you have an arduino , you don't need an LM555 ic.
You already have PWM output. All you need to do is use the PWM library and a mosfet driver chip, which you need because at 16 kHz, the arduino can't charge and discharge the mosfet gate fast enough due to the large currents necessary at that speed.
Look at this sketch:
// Arduino UNO DDS
#include <PWM.h>
int32_t frequency_9 = 12000; //frequency (in Hz)
int32_t frequency_3 = 16000; //frequency (in Hz)
void setup()
{
InitTimersSafe();
SetPinFrequencySafe(9, frequency_9);
SetPinFrequencySafe(3, frequency_3);
}
void loop()
{
int val = analogRead(A0);
val = map(val, 0,1023,0,100);
int dutyC =512; // Duty Cycle 0 (0%) - 1023(100%)
pwmWrite(9, dutyC / 4);
pwmWrite(3, val);
delay(30);
}
I can post a photo of the oscilloscope screen while running this but I don't think it's necessary. The period is 60 us so the frequency is 16,666 Hz.
If you use this sketch with this mosfet driver chip (powered by a 12V regulator on a heatsink)
and the same power mosfet you already have on that board (by doing a real hack and cutting the trace to the gate and connecting it to the output of the mosfet driver) The souce will need to connect to the motor supply GND and the arduino GND.
The mosfet driver chip would need to be powered by 12V/1.5A supply.
You will be able to control the same motor , running on the same voltage, using either a pot (like the one used in the sketch connected across 5V & GND with the wiper connected to A0 ), or you can comment out that code and use code to control the duty cycle.
Doesn't that make more sense that fooling around with a 25 cent 555 timer chip ?
