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Generally speaking, hot-plugging devices/sensors onto the GPIO pins of a running Pi is a potentially device/Pi damaging bad practice. But does that hold true for a PL2303TA chipset-based USB to TTL Serial Cable? Like this. Since one side is USB, is there some sort of power sequence inherent within USB that might make this a safe practice?

Like maybe plug the GPIO pins first then plug in the USB to my PC.

PI TTL Serial Cable Connection

The reason that I want this is that, sometimes when my Pi's lose Wi-Fi connectivity, my network detection/restart scripts on the Pi are unsuccessful in restarting the Wi-Fi connection. This leaves me without a way to log into the Pi.

  • USB is hot-pluggable by design. It's not different on the Raspberry Pi. – Janka Jan 22 '18 at 21:23
  • @Janka, as a general StackExchange rule, please do not post answers as comments. As you say hotplugging should work (as per spec) so that should be an answer. – Ghanima Jan 22 '18 at 21:28
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Yes, provided you are sure it is compatible. Adafruit sells such an adapter. From the product description on that page:

The power pin provides the 5V @ 500mA direct from the USB port and the RX/TX pins are 3.3V level for interfacing with the most common 3.3V logic level chipsets.

Do be careful connecting 5V power. Generally, you want to power the RPi through a separate power supply, not via the USB adapter.

As to specific sequence, I'm not aware of any. I had no issues plugging and replugging into a PC USB port. YMMV.

  • I attach one of these FTDI cables to my Raspberry Pi devices all the time. It's really the only way to debug a live unit that can't connect to the network for some unknown reason. You just need to make sure that the GPIO serial console is enabled using raspi-config. – HeatfanJohn Jan 23 '18 at 4:29

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