I need to invert the TX on UART1. I see the INVT bit in the UART1_UCR3 register but I don’t know the “right” way to set it in my Linux application. Can I do it through a shell with something like stty?
Thank you. That was my assumption after digging through the uart driver. Its looking for a “fsl,inverted-tx” string which I was pretty sure goes in the device tree somewhere.
I’ve spent quite a bit of time with the device tree and device tree overlay tutorials from Toradex but I get stuck when it tells me to look in arch/… for the device tree and tools. Where is that directory? Do I need to checkout the kernel source from somewhere?
how can I set DTE mode with fsl,imx8qxp-lpuart (imx8qxp)? LPUART doesn’t seem to have
The iMX8QXP has a different UART IP block and doesn’t support DCE/DTE switching.
you can use fsl,invert-tx and fsl,invert-rx if you just need to invert one or both such as is in my case.
It does not apply for lpuart (iMX8QM, IMX8QX)
Ok, so if I have a GSM modem that is DCE and expects other part to be DTE, what can I do? Or what is is by default?
Bummer. Obviously I didn’t try it, a transistor was a simpler solution in my case.
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Just connect RX line of iMX8 UART to TX line of your modem. Or check if a modem can be configured in DCE/DTE mode
The GSM module manual calls TXD an input and RXD an output, while imx8qxp manual calls TXD an output and RXD an input. This means I must connect TXD-TXD and RXD-RXD, right?
From SARA R4 manual:
UART signal names of the cellular modules conform to the ITU-T V.24 recommendation e.g. TXD line represents data transmitted by the DTE (host processor output) and received by the DCE (module input).
From imx8qxp manual:
Thank you for your help!
Are you using Colibri iMX8X or Verdin iMX8M plus? This topic was created for Verdin iMX8M plus. Please create a new thread If you are using Colibri iMX8X.