Hi folks, I'm currently developing a sensor framework based on the TWI bus and I use ATtiny85's as sensor nodes. I want them to be able to communicate as TWI master, therefore I wanted to implement the USI in TWI mode with Timer0 as clock. So my questions are: 1. Do I have to use OCR0A or OCR0A? 2. When using Timer0, do I have to generate the clock manually or is it done by the HW? 3. For bus arbitration I would need to detect if the bus is in use. Is there a efficient way the detect stop conditions? Unfortunately not even AVR believes in the USI interface and the whole application notes depend on polling and the ATtiny85's datasheet is very vague on this topic. Thanks in advance.
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You intend to make the I2C-communication by yourself? In this connection I can't help. I use Bascom and there is a library for master and slave which use the USI-HW. I suppose a simular library is available in C. So you have nothing to do with bits, clock and timer. This is quite simple. To practice I have made a master which reads and writes an EEPROM. And then I made a slave which emulates this EEPROM. The only problem: the slave library costs about 14€ for all SW and HW solutions. If you are interested I can post the short source code.