ATTiny 861A pin assignment ========================== (MOSI/DI/SDA/!OC1A/PCINT8) PB0 MOSI,LED4 SENSE1+ PA0 (ADC0/DI/SDA/PCINT0) (MISO/DO/OC1A/PCINT9) PB1 MISO,PWM1 SENSE12- PA1 (ADC1/DO/PCINT1) (SCK/USCK/SCL/!OC1B/PCINT10) PB2 SCK,LED5 SENSE2+ PA2 (ADC2/INT1/USCK/SCL/PCINT2) (OC1B/PCINT11) PB3 PWM2 LED6 PA3 (AREF/PCINT3) VCC AGND GND AVCC (ADC7/!OC1D/CLKI/XTAL1/PCINT12) PB4 SW2 LED7 PA4 (ADC3/ICP0/PCINT4) (ADC8/OC1D/CLKO/XTAL2/PCINT13) PB5 PWM3 SENSE3 PA5 (ADC4/AIN2/PCINT5) (ADC9/INT0/T0/PCINT14) PB6 SW1 SENSE4 PA6 (ADC5/AIN0/PCINT6) (ADC10/RESET/PCINT15) PB7 RST SENSE5 PA7 (ADC6/AIN1/PCINT7) Components ========== PWM1 LED1 rear spotlight: step-down, differential SENSE1 PWM2 LED2 rear LED strip: step-up, differential SENSE2 PWM3 LED3 front light: step-down, single-ended SENSE3, inverted stride SENSE4 - ambient light sensor, single-ended SENSE5 - battery voltage sensor, single-ended LED4 - status LED (green) LED5 - error LED (red) LED6 - speedometer illumination LED LED7 - front UV LED SW1 - on/off; mode switch SW2 - temporary light boost or whatever ADC Gain ======== 0.033R sensign res. single-ended resolution: 0.001074 V .. 1.1000 V 32.55 .. 33333 mA differential resolution 8x gain: 0.000134 V .. 0.1375 V 4.06 .. 4166 mA differential resolution 20x gain: 0.000054 V .. 0.0550 V 1.64 .. 1666 mA differential resolution 32x gain: 0.000036 V .. 0.0344 V 1.09 .. 1042 mA analog input resistance 100 MOhm PWM LED current sense ===================== 0.033R sensing resistor: max gain min gain 20 mA => 0.00066 V 8x 100 mA => 0.0033 V 150 mA => 0.0050 V 300 mA => 0.0099 V Power burned at sensing resistor: 350 mA => 0.0116 V 0.004 W 700 mA => 0.0231 V 0.016 W 1000 mA => 0.0330 V 32x 0.033 W 1500 mA => 0.0495 V 20x 0.074 W 2000 mA => 0.0660 V 8x 0.132 W 3000 mA => 0.0990 V 8x 0.297 W Battery sense ============= range 5-15 V 1.5M..100k voltage current sense voltage 15V: 9.3 uA 0.94 V 12V: 7.5 uA 0.75 V 5V: 3.1 uA 0.31 V Ambient light sensor ==================== 5 V, 1M5 resistor + photodiode: voltage at the photodiode darkness: 3.71 V => 4.31 MOhm bathroom without lights, only outside lights: 3.68 V => 4.18 MOhm kitchen light: 3.29 V => 2.89 MOhm room 30min before midnight: 0.26 V => 82 KOhm outside 30min before midnight: 0.05 V => 15 KOhm bathroom halogen lights 0.02 V => 6 KOhm battery light: 0.01 V => 3 KOhm Use 1M5 main resistor + 300K sensing resistor, 1.1V single-ended sense Expected voltage ADC readings darkness: 0.244 V 226.8 bathroom: 0.249 V 231.8 kitchen light: 0.318 V 296.2 halogen light: 0.831 V 773.1 battery light: 0.832 V 774.5 Plain LEDs ========== @5 V source 20 mA/3V: 100 R resistor 20 mA/2V: 150 R resistor 2 mA/2V: 1K5 resistor Battery idle current ==================== 2000 mAh: 1.0 mA -> 83 days capacity 2000 mAh: 0.1 mA -> 833 days capacity Converter reaction ================== step-up: 4-5 adc measurements to ADC voltage increase step-down 2: 1-2 ---""--- timer: 34-38 ADC measurements per jiffy (200 Hz)