ADM2486 with i.MX8M plus

Hello, thanks for your query,

ADM2486 is a half duplex RS-485 transceiver, so the same A/B signal lines are used for both transmitting and receiving, but not at the same time. The device must be configured to either transmit or receive, DE and #RE pins are used for this flow control. Typical half duplex connection is to connect both #RE and DE together, and control from the processor using a single transmit/receiver signal (DE/#RE). 

When DE/#RE signal is driven high by the processor, the ADM2486 is in transmit mode, all data applied to the TxD pin will be send to the RS-485 bus, and the RxD receiver output will remain inactive. When the DE/#RE signal is driven low by the processor, the ADM2486 is in receive mode, all incoming data from the RS-485 bus will be received at the RxD pin, and the TxD transmitter input will remain inactive. 

In this configuration it's worth adding a weak pullup resistor to the RxD pin (eg. 47kohm) to pull this high when the receiver is inactive. 

The DE/#RE pin can be driven by a GPIO, or some UART blocks have the facility to drive this pin, usually listed in the UART manual as "hardware flow control" 

Regards,

Neil 

Thanks!