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ranran
Senior
Nov 1, 2019 8:14 AM UTC
Solved

Can we access I2C in 7-bit data ?

Hello,

As far as I understand, I2C access with STM32H7 supports only 8-bit data.

But we need 7-bit data. Is that possible ?

Thanks

This topic has been closed for replies.
S.Ma
S.MaBest answer
Principal
Nov 1, 2019 12:46 PM UTC

I2C specification states 8 bit data + ACK bit.

If 7 bits then it's no longer called I2C.

6 replies

S.Ma
S.MaBest answer
Principal
Nov 1, 2019 12:46 PM UTC

I2C specification states 8 bit data + ACK bit.

If 7 bits then it's no longer called I2C.

S.Ma
Principal
Nov 1, 2019 12:47 PM UTC

And then the answer is no. Use SW I2C with GPIO to build customized waveforms for the pseudo I2C.

Or maybe there is confusion for the slave address, it's 7 bit + Read/write bit = 8 bits

Tesla DeLorean
Guru
Nov 1, 2019 12:53 PM UTC

Perhaps you can post information about what device you're trying to communicate with, and the "7-bit" mode you're talking about.

The address is 7-bit wide, perhaps you're confusing terms/requirements, but question lacks sufficient context.

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ranran
ranranAuthor
Senior
Nov 1, 2019 1:14 PM UTC

Hi,

I was speaking of data width - not address mode.

So, according to previous answers here, it seems that data must be used with 8-bit bytes only.

Thank you

Tesla DeLorean
Guru
Nov 1, 2019 1:25 PM UTC

Ok, but it what context? What device needs/provides such a mode?

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ranran
ranranAuthor
Senior
Nov 1, 2019 3:52 PM UTC

It is not for a specific device, but only optional for any for future device requiring 7-bits data.

Thanks