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Posts: 4
Registered: ‎03-17-2017

SI7021

hi guys. i tried to read data from SI7021 temperature sensor. I got data of 0XFF. here is sequence i sent.

 

start

write 0x40

write 0xF3( temperature no hold mode)

repeat start

write 0x41

read data

stop

 

i found for every 9th bit of SDA is HIGH, which means that master does not receive ack from slave. then for data bytes, i have 0xff. can someone help me out?. do i need to initiate anything?

Posts: 30
Registered: ‎06-10-2015

Re: SI7021

The address is 7-bits, 0x40, which then needs to be followed with a 0 for write or 1 for read. The initial I2C address write should be 0x80. The sensor should ACK this. Is this what you are seeing?