Jetson Orin Nano 为什么我的UBUNTU上查看tty设备，只有ttyTHS0,ttyTHS3,ttyTHS4,没有ttyTHS1,ttyTHS2,这是哪里的问题，而且应该有两个串口输出数据，但是只有ttyTHS0输出
I don’t know if anything is actually missing, but here is some information you might find useful…
The integrated UARTs can use either a legacy driver of the “Tegra High Speed” driver. If the driver is legacy, then the file name is of the format “/dev/ttyS#”, and if it is from the THS driver, then the name is “/dev/ttyTHS#”. The integrated UARTs can use either driver, so it is possible that both a ttyS# and a ttyTHS# are available simultaneously for a single UART (it would be a bad idea to use both drivers at the same time). It is the device tree which tells drivers (for integrated UARTs; plug-n-play USB UARTs are different) should bind to a given UART at a particular physical address.
Someone else would need to verify which drivers for integrated UARTs are intended to produce a device special file in “/dev”. As an example, I think there might be a Wi-Fi UART not accessible as a “/dev/ttyTHS#”.
是的，本来自带的一个WIFI/BT网卡，但是我把它卸载掉了，驱动也卸载了，想把它使用的那个串口作为一个普通的输出串口，但还是找不到对应的tty设备。
Someone from NVIDIA would have to comment for that specific UART. Basically, the device special file exists if the UART driver loads. The UART is not plug-n-play, and so finding the UART and binding that UART to a driver is a function of the device tree. In part the device tree is specified with a “serial@<hex address>” node, and within that node is a “compatible” line to name the driver(s) (it is a comma-delimited list of drivers). Should that be present, then the driver will load. If the “udev” system is not used to rename that UART, then the driver is what determines the device special file name (udev can rename the file).
Do you know the physical address of that UART? I do not personally know the answer to that, although NVIDIA could answer this. If you know the physical address, then you could search for that in the serial console boot logs and it would probably tell you more about that device and its driver (perhaps even telling you the device special file name, or a log of udev working on that file).
谢谢，问题解决了。但是我有个新问题。两路串口接收北斗卫星的数据，但是只有一路串口可以给卫星发命令，这会是什么原因？
I couldn’t answer that. It depends on what you mean by “send”. Do you have an oscilloscope whereby you can monitor the TX, RX, CTS, and RTS pins? One possibility is that CTS/RTS flow control is enabled at one end, but not at the other end. For example, if the Jetson does not require CTS/RTS flow control, then even if the other side does use this, the Jetson won’t care and will receive anyway, but the other direction, sending out, would fail for lack of the CTS/RTS. Or, if the oscilloscope shows no traffic, then it means something internal to the setup of the UART.
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