6 void backlight_init_ports()
8 // Setup PB7 as output and output low.
12 // Use full 16-bit resolution.
15 // I could write a wall of text here to explain... but TL;DW
16 // Go read the ATmega32u4 datasheet.
17 // And this: http://blog.saikoled.com/post/43165849837/secret-konami-cheat-code-to-high-resolution-pwm-on
19 // Pin PB7 = OCR1C (Timer 1, Channel C)
20 // Compare Output Mode = Clear on compare match, Channel C = COM1C1=1 COM1C0=0
21 // (i.e. start high, go low when counter matches.)
22 // WGM Mode 14 (Fast PWM) = WGM13=1 WGM12=1 WGM11=1 WGM10=0
23 // Clock Select = clk/1 (no prescaling) = CS12=0 CS11=0 CS10=1
25 TCCR1A = _BV(COM1C1) | _BV(WGM11); // = 0b00001010;
26 TCCR1B = _BV(WGM13) | _BV(WGM12) | _BV(CS10); // = 0b00011001;
28 // Default to zero duty cycle.
32 void backlight_set(uint8_t level)
36 // Turn off PWM control on PB7, revert to output low.
37 TCCR1A &= ~(_BV(COM1C1));
41 // Turn on PWM control of PB7
42 TCCR1A |= _BV(COM1C1);
43 OCR1C = level << 12 | 0x0FFF;