Hi folks, finally got myself a cheapo logic analyser today and decided to test using a combination of my bus pirate and MCP7190 RTC.

Everything seems to be decoded ok as I2C apart from the initial address request made by the BP, instead of 0xde, pulseview shows 0x6f. The binary clearly is correct, RTC responding and all data is correct after this initial address.

Can anyone shed light on what might be happeneing??

 

I don't see a problem You have written 0xDE and that is made up of 0x6F and a write bit of 0.. looks okay.

 

The I2C address is 7 bits long, and the read/write bit is just that: a bit. Shove them together and you get one byte.

Top seven bits are the address, lowest bit is read/write.

If you multiply 0x6F by 2 you get 0xDE.

 

ok I did not see that. Thanks