A weblog focused on interesting circuits, ideas, schematics and other information about microelectronics and microcontrollers.
AVR-CDC is a pure SW based USB-RS232C interface using the CDC (Communication Device Class) protocol. Although the bulk endpoint required for CDC is not allowed within the low-speed USB standard, it works fine on major platforms.
Program size is about 3KB on AVR. Since ATtiny45 has no USART, 4800bps may be the practical speed. ATmega8/48/88 can achieve the higher transfer rate (e.g. 38400bps) using the internal USART. The AVR-CDC is based on Object Development's AVR-USB. The portion of code that I added is published as free software (GPL2). See the License.txt together with the Object Development's license agreement.