PCF8575C: Pulse signal recognition

Yongki Jeong1

Part Number: PCF8575C
Other Parts Discussed in Thread: BQ25601, PCF8575, SN74LVC2G74, TCA8418

Hi Ti Team

I plan to use several 'BQ25601(4EA~)' by connecting them to the MCU.
MCU needs to read the INT signal of BQ25601 through PCF8575,
Can MCU recognize pulse signal through PCF8575?

Sincerely

Jeong

over 2 years ago

+1 Clemens Ladisch over 2 years ago

Guru 285560 points

The PCF will activate its interrupt output when any input pin changes, but it will deactive the interrupt when the input changes back. So you can recognize the signal only when you read the input port of the PCF quickly enough.

If you cannot guarantee that you have completed the read inside of 256 µs, then you have to store the interrupt state in a flip-flop (e.g., SN74LVC2G74) and to clear it manually.

0 Chris Ayoub over 2 years ago in reply to Clemens Ladisch

TI__Genius 15345 points

Hi Jeong,

Just to add onto what Clemens said, we don't have any I/O expanders currently that latch the INT pin when an input port changes value. The TCA8418 does but it is more of a keypad scanner.

Best,

Chris

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PCF8575C: Pulse signal recognition