Changes between Version 20 and Version 21 of serial


Ignore:
Timestamp:
10/11/2019 12:19:18 AM (5 weeks ago)
Author:
Tim Harvey
Comment:

added additional details for Newport and clarified that CN80XX GPIO12 maps to Linux gpio-476

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  • serial

    v20 v21  
    225225The following table and sections below provides per-board details of RS485:
    226226||= Family  =||= Board                 =||= TXEN  =||= Transceiver =||= Termination =||= Fail-Safe Bias =||= Notes =||
    227 || Newport   || GW630x / GW640x                 || gpio12  || [https://www.exar.com/ds/sp335e.pdf SP335E] || optional (gpio16) || included || ||
     227|| Newport   || GW630x / GW640x                 || gpio476  || [https://www.exar.com/ds/sp335e.pdf SP335E] || optional (gpio16) || included || ||
    228228|| Ventana   || GW52xx '''(optional)''' || gpio193 || [http://dev.gateworks.com/datasheets/MAX14840E-MAX14841E.pdf MAX14840] || optional     || optional || TIOCSRS485 support ||
    229229||           || GW53xx '''(optional)''' || gpio193 || [http://dev.gateworks.com/datasheets/MAX14840E-MAX14841E.pdf MAX14840] || optional     || optional || TIOCSRS485 support ||
     
    324324 * optional on-board termination (enabled by gpio16)
    325325 * in-chip fail-safe protection to default idle inputs to logic-high (no external bias resistors required)
    326  * TXEN connected to gpio12
    327 
    328 The pl011 Linux driver supporting the CN80XX serial ports (SERIAL_AMBA_PL011 drivers/tty/serial/amba-pl011.c) does not look like it supports RS485 directly. While this support could be added you can alternatively drive the TXEN gpio12 directly in a user application for RS485 half-duplex.
     326 * TXEN connected to CN80XX gpio12 which it typically Linux gpio476
     327
     328The pl011 Linux driver supporting the CN80XX serial ports (SERIAL_AMBA_PL011 drivers/tty/serial/amba-pl011.c) does not look like it supports RS485 directly. While this support could be added to the serial driver in the future you can alternatively manage the TXEN (gpio476) directly in a user application (asserting TXEN prior to calling write() then using tcdrain() to wait for the UART FIFO to be empty before deasserting TXEN). For RS485 half-duplex using (see example below).
    329329
    330330