[GreenKeys] USB to TTY (model15) interface

[John Nagle]

On 2/12/23 11:55, greenkeys-request at mailman.qth.net wrote:
> Message: 7
> Silicon Devices has, however, a development kit where everything is
> unlocked.? There is also a utility available to set any arbitrary baud
> rate that is wanted. Note that you have to use the older development
> kit.? The one with an "N" in it was "improved" in a way that no longer
> supports 45 baud.? As far as I know, the original kits are still
> available but I wouldn't expect them to be around forever.? I bought a
> couple of spares.
> 
> More information on the device can be found here:
> 
> https://www.aetherltd.com/connectingusb.html
> 
> PDW

Yeah, unfortunately the CP2102N will not go down to 45 Baud.

I brought this up with SIlabs, and they put it in a tech
note.

https://www.silabs.com/documents/public/application-notes/an976-cp2102-3-4-9-to-cp2102n-porting-guide.pdf

In there, SILabs writes:

The CP2102N is feature compatible with the CP2102/9, with two exceptions:
• Baud Rate Aliasing
• Line Breaks / Break Conditions
Baud Rate Aliasing is a feature that allows a device to use a 
pre-defined baud rate in place of a baud rate that is requested by the user.
For example, a device using Baud Rate Aliasing can be programmed to use 
a baud rate of 45 bps whenever 300 bps is requested.
Baud Rate Aliasing is not supported on the CP2102N.
If Baud Rate Aliasing is used in a CP2102/9 design, the CP2102N is 
incompatible as a replacement.

The CP2102 is now listed as "Not for New Designs".
DigiKey says they still have 44,000 available, though.

It looks like the end of the line for UART hardware which can
operate at 45 baud. The future is CPU-emulated UARTs, probably.

				John Nagle