THVD2410: Driving RE and RE from a single pin

Marco Dassi

Part Number: THVD2410

Hello,

I've to design a RS485 half-duplex communication line, and I'm running out of microcontroller pin to drive RE and DE separately; I'm pretty sure I've done it in the past (with another chip), but I'd like a confirmation from you fellow engineers if this solution is working:

when RS485_DIR signal is LOW, rx is enabled and tx is disabled

when RS485_DIR signal is HIGH, rx is disabled and tx is enabled

I've no need to put the chip in standby or in low power mode

Thank you very much for your time, best regards

over 2 years ago

+1 Clemens Ladisch over 2 years ago

Guru 268120 points

The DE/RE pins have opposite polarity in order to allow them to be controlled like this.

Alternatively, leave /RE always enabled, and ignore the data you're sending yourself (or monitor it for errors).

0 Marco Dassi over 2 years ago in reply to Clemens Ladisch

Prodigy 200 points

Thank you Clemens, just what I was thinking.

In fact, I've found out some of my old schematics, and in one case the RE was forced to GND, and in the other I've shorted DE with RE (I think it have no sense to monitor the byte you've just sent)

Thanks again, have a nice day!

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THVD2410: Driving RE and RE from a single pin