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Embedded module TQMa57xx - YOCTO Linux BSP documentation



RS485 bus block in half-duplex mode
Affects RS485 via UARTx on MBa57xx Revsion 01xx
Issue During AM57xx reset the UARTx.CTS# pin is low by default (CPU internal pull down)
Effect Using the AM57xx RS485 circuitry in a half-duplex slave device or half-duplex multi-master environment may block the RS485 bus during AM57xx reset.
The bus is released as soon as the UARTx.CTS# pin is properly configured by software (e.g. U-Boot, Linux, etc.)
Solution / Workaround Add a 10k pull up to the UARTx.CTS# signal on carrier board
This behaviour will be fixed with MBa57xx REV.02xx
  • Last modified: 2022/08/04 15:02