Trying to rescue a GPU cooling system containing a 12V 4-wire fan using a PWM signal from ATtiny85 and reading a voltage from ADC from a potentiometer knob. Ultimately building a 4-wire fan controller.
25kHz PWM on ESP8266: https://github.com/esp8266/Arduino/issues/4598
Software
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| /* | |
| * ATtiny85 | |
| * -------u------- | |
| * RST - A0 - (D 5) --| 1 PB5 VCC 8 |-- +5V | |
| * | | | |
| * A3 - (D 3) --| 2 PB3 PB2 7 |-- (D 2) - A1 --> 10K Potentiometer | |
| * | | | |
| * A2 - (D 4) --| 3 PB4 PB1 6 |-- (D 1) - PWM --> Fan Blue wire | |
| * | | | |
| * Gnd ---| 4 GND PB0 5 |-- (D 0) - PWM --> Disabled | |
| * ----------------- | |
| */ | |
| // normal delay() won't work anymore because we are changing Timer1 behavior | |
| // Adds delay_ms and delay_us functions | |
| #include <util/delay.h> | |
| // Clock at 8mHz | |
| #define F_CPU 8000000 // This is used by delay.h library | |
| const int PWMPin = 1; // Only works with Pin 1(PB1) | |
| const int PotPin = A1; | |
| void setup() | |
| { | |
| pinMode(PWMPin, OUTPUT); | |
| // Fast PWM Mode, Prescaler = /8 | |
| // PWM on Pin 1(PB1), Pin 0(PB0) disabled | |
| // 8Mhz / 8 / (39 + 1) = 25Khz | |
| TCCR0A = _BV(COM0B1) | _BV(WGM01) | _BV(WGM00); | |
| TCCR0B = _BV(WGM02) | _BV(CS01); | |
| // Set TOP and initialize duty cycle to zero(0) | |
| OCR0A = 39; // TOP - DO NOT CHANGE, SETS PWM PULSE RATE | |
| OCR0B = 0; // duty cycle for Pin 1(PB1) - generates 1 500nS pulse even when 0 | |
| } | |
| void loop() | |
| { | |
| int in, out; | |
| in = analogRead(PotPin); | |
| out = map(in, 0, 1023, 0, 39); | |
| OCR0B = out; | |
| _delay_ms(200); | |
| } |