IO Expander for ATTiny45/85 that offers one PWM output channel and up to 3 analog input channels using the I2C bus
The default address is 0x60 I2C has been tested with Arduino UNO, Nano and the ESP8266 Examples of I2C commands can be found in tinypwm.h
PB0 / pin 5 = SDA PB2 / pin 7 = SCL PB1 / pin 6 = PWM output PB3 / pin 2 = ADC #1 PB4 / pin 3 = ADC #2
PB1 can be used to output a PWM signal with a given frequency from 488 to 65535Hz. For different frequencies timer1 can be programmed directly
The frequency can be set with the SET_PWM_FREQUENCY command. The data for the command is the frequency as uint16.
Example for 20kHz
0x60(slave address) 0x51(SET_PWM_FREQUENCY) 0x20 0x4e(PWM frequency)
The duty cycle is set with the ANALOG_WRITE command and the data is the PWM value as uint8_t
Example for 50% duty cycle
0x60 0x10(ANALOG_WRITE) 0x00(PB1) 0x7f(127)
The max. duty cycle is 255, but not all frequencies support the full range. For these cases the values are mapped
PB1, PB3, PB4 and PB5 can be used as ADC input channels. If Pin5 is used, the reset pin must be disabled by programming the Fuse High Byte (see Table 20-4, https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-2586-AVR-8-bit-Microcontroller-ATtiny25-ATtiny45-ATtiny85_Datasheet.pdf)
The selected channels are constantly read and the values or averages value stored. Requesting a reading does not block and returns the last stored value. By default, the internal 2.56V reference is set
0x60 0x11(ANALOG_READ) 0x01(PB3)
0x60 0x11(ANALOG_READ) 0x02(PB4)
The response is an uint16 with the value.
The pin number is a sequential number in the order of the analog pins specified during compilation
Set voltage reference to 1.1V
0x60 0x62(ADC_SET_AREF) 0x02(internal 1.1V)
- Multiple output or input pins
- Pins can be configured with pinMode
- Write current settings as default configuration to EEPROM
- digitalRead/Write added
- up to 3 analog input channels
- Initial version