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Hello in I2C we send data to the slave using I2C->TXDATA register. on the same line we need to receive ACK response from the slave.

From SPI experience I know that for the slave to respond master needs to send the slave it dummy bits to provide it with clk.

But the ACK is only one bit, how do I provide a clock of 1 bit? Thanks.

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  • \$\begingroup\$ SPI and I2C are different. Experience with one may not help with the other. To answer teh specific question; to clock one bit, pulse SCL once. That's it. From the data you supply, you appear to be using an I2C core on some MCU : that should handle it for you. \$\endgroup\$
    – user16324
    Commented Oct 18, 2020 at 20:22

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Every transaction requires you send nine clock pulses from the master, the month byte is for the ACK bit.

For the slave address transaction the data line is left high from the master so the slave can acknowledge the address if recognized.

If you are using the I2C hardware it will automatically send nine clock pulses. If being implemented in software you will need to send all nine clocks by setting the clock high and then low.

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  • \$\begingroup\$ Hello Kevin, I am asking regarding sending data from slave to masker. In SPI for the slave to respond on MISO we need to provide it with CLK from the master by sending extra dummy bits on the MOSI line. Do we need in I2C to send CLK to the slave for it to respond? Thanks. \$\endgroup\$
    – rocko445
    Commented Oct 19, 2020 at 5:02

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