Code for ATtiny45 interfacing HC-SR04 module and sending measurement results via UART. Default UART speed is 9600 baud. Measurement results (in cm) are sent one-per-line.
Use avr-gcc to compile the code, or just program included HEX file into ATtiny45.
Fuse bytes: low: 0xEE high: 0xDF ext: 0xFF