UART RTS CTS

      Dear Mr. Schubert,

      it is not possible to have the RTS/CTS pins of UART_B on connector pins 19/21. No one of the UART_B RTS/CTS pins goes to connector. And yes only UART_A is the only full connected UART on armstoneA9.

      Your F&S Support Team
      F&S Elektronik Systeme GmbH
      As this is an international forum, please try to post in English.
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      A non-standard solution would be possible. Non-standard means that this is only possible on the armStoneA9 because of a coincidental possibility in the pinmux. But no other armStone will have this feature on these pins.

      You could have an additional full UART with RTS/CTS on pins 19, 20, 23, 24 and a restricted one with only TXD/RXD on pins 21, 22. But this is currently not supported in our device tree. So in fact up to five different UARTs are possible on the regular armStoneA9.

      Your F&S Support Team
      F&S Elektronik Systeme GmbH
      As this is an international forum, please try to post in English.
      Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.

      Post was edited 1 time, last by “fs-support_HK” ().

      Hello,

      fs-support_HK wrote:

      A non-standard solution would be possible.
      You could have an additional full UART with RTS/CTS on pins 19, 20, 23, 24 and a restricted one with only TXD/RXD on pins 21, 22. But this is currently not supported in our device tree. So in fact up to five different UARTs are possible on the regular armStoneA9.

      To clarify the non standard solutions for an additional UART are just possible using the pins described above. 19,29,23,24 for a full UART or 21,22 for just RX/TX.
      This is interesting if you want to have an additional UART besides or instead of the default UART interfaces

      But your desired (very specific) configuration getting an additional RTS/CTS signal exactly on pins 19/21 is not possible. Even if we look for an RTS/CTS signal of any UART.
      There is simply no multiplex option on the pads. The multiplex options for pin 19 are:
      ALT1 EIM_DATA08
      ALT3 UART4_TX_DATA
      ALT5 GPIO5_IO30
      ALT7 ARM_TRACE09

      and for pin 21
      ALT0 IPU1_CSI0_DATA14
      ALT1 EIM_DATA10
      ALT3 UART5_TX_DATA
      ALT5 GPIO6_IO00
      ALT7 ARM_TRACE11

      Best Regards
      Your FS Support Team
      F&S Elektronik Systeme GmbH
      As this is an international forum, please try to post in English.
      Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.
      Thanks for your detailed answer. I guess I understand. I thought it's possible because on armstoneA9r2 these pins are used this way but I see that the wiring to the GPIO extender is completely different (between A9 and A9r2).
      Please one last question to this topic: How to use the pins 19,20,23,24 for full UART?

      Many thanks again for support.
      You're welcome :)

      How to setup:
      This configuration is all done in the devicetree (arch/arm/boot/dts/armstonea9qdl.dtsi) in the node called &iomuxc and the subnodes there.
      Have a look there to understand how it works.

      To get UART4 you have to:
      - create a new &uart4 node. See how it is done with the other uart nodes.
      - create the &pinctrl_uart4_1 node with the 4 lines you have chosen above.

      If there are other pinmux configurations for the pads you want to use you have to disable/uncomment these functions. This means there can't be a pinmux setting e.G. that is called: MX6QDL_PAD_CSI0_DAT12__GPIO5_IO30
      Because we want to use the CSI0_DAT12 pad for the UART signal e.G. like this: MX6QDL_PAD_CSI0_DAT12__UART4_TX_DATA

      For the pinctrl node you need 4 lines. These are the possibilities for the pins:

      19
      MX6QDL_PAD_CSI0_DAT12__UART4_TX_DATA
      MX6QDL_PAD_CSI0_DAT12__UART4_RX_DATA

      20
      MX6QDL_PAD_CSI0_DAT13__UART4_RX_DATA
      MX6QDL_PAD_CSI0_DAT13__UART4_TX_DATA

      23
      MX6QDL_PAD_CSI0_DAT16__UART4_RTS_B
      MX6QDL_PAD_CSI0_DAT16__UART4_CTS_B

      24
      MX6QDL_PAD_CSI0_DAT17__UART4_CTS_B
      MX6QDL_PAD_CSI0_DAT17__UART4_RTS_B

      So you can decide if RX or TX should be on pin 19 or 20.
      And on which of the pins 23, 24 RTS or CTS should be.

      Best Regards
      Your F&S Support Team
      F&S Elektronik Systeme GmbH
      As this is an international forum, please try to post in English.
      Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.