Devices with only USB console port - Need a Console Server Solution

Keenan Tims ktims at stargate.ca
Tue Feb 2 20:06:38 UTC 2016


On 2016-02-02 02:02, Bjørn Mork wrote:
> As you are probably aware, there are no standard
> USB-DB9 Console adapters.  They are all vendor specific.  But the
> cloning industry has created a few semi-standards based on specific
> chipsets.
This is not strictly true. There is a Communications Device Class (CDC
ACM) defined by the USB-IF that covers basic serial devices and most OSs
(even Windows! Though it does require a .inf file anyway) include a
driver for it. A rumour I heard recently was that its lack of popularity
was a result of Microsoft and Intel not wanting device developers to
ignore the advantages of USB and just use CDC to continue using their
old-school RS232 protocols for mice or whatever. There are also some
good reasons not to use it, such as flow control, strict timing, higher
data rates, and added features available with custom chipsets, but it's
just fine for a serial console.

Exar, Microchip and others make simple and cheap USB-UART chips using
CDC ACM, and it's a very common application example for USB
microcontrollers.

USB console ports are just adding complexity where it offers no
advantage. KISS.

Keenan



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