TCA6424A: Interval time for I2C command

Shunsuke Nagata

Part Number: TCA6424A

Hi,

Could you please let me know about TCA6424A?

1. Datasheet 8.4.4.1 : How long will Ack be replied after sending write command? (How long MCU should wait ACK after sending write command?)

2. Datasheet 8.4.4.2 : In the case of Write command -> Read command, is there a limit time between ACK and start?

Regards,
Nagata.

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 268780 points

This device conforms to the I²C specification.

1. The TCA6424A (like almost any other I²C device) pulls SDA low at the falling edge of the eighth clock pulse. This ensures that SDA is stable when SCL is high during the ninth pulse. The TCA6424A does not do clock stretching, so you do not need to wait longer than that.

2. No; the read command can follow immediately, and the TCA6424A does not do clock stretching.

0 Eric Schott1 over 3 years ago

TI__Guru 50795 points

Hi Nagata,

I can confirm what Clemens explained. The I2C interface can be thought of as a state machine which is clocked by SCL. As long as the max data rate of the device is respected, no artificial delay needs to be introduced on the SCL line or between frames (ACK and start).

Regards,
Eric Schott

0 Shunsuke Nagata over 3 years ago in reply to Eric Schott1

TI__Genius 12420 points

For #2, Controller (MCU) will have wait before start condition. will the TCA6425A have issue?

Regards,
Nagata.

0 Eric Schott1 over 3 years ago in reply to Shunsuke Nagata

TI__Guru 50795 points

Hi Shunsuke,

No, there will be no issue if there is a long delay between frames.

Regards,
Eric Schott

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TCA6424A: Interval time for I2C command