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Cannot communicate on 460800 baud thumbDV with FTDXX2 library #thumbdv

hayley@...
 

Hello,
I am trying to use the FTD2xx.h library to communicate via serial port with the new ThumbDV at the higher baud rate. However, I am having a lot of issues. Almost no audio packets are going through and somehow the AMBE chip keeps sending pkt reset packets. The same code base is used for the 230400 baud rate and works just fine. I tried to reach out to the FTDI team to get help. They made sure I was using RTS/CTS flow control but could not help me any further since this is a third party device. Can someone please help me figure out how to communicate at this higher rate?

Annaliese McDermond
 

I am not aware of anyone using the library to communicate with the chip. I use standard tty IO with Buster and it works fine at 430800.  I’ve also worked with the chip on Linux while doing some rewrites of AMBEserver and also use tty IO at the higher baud rate just fine. 

So, sorry I can’t answer your question directly, but as far as UNIX-like OSs go, I know of nobody using the FTDI library to drive it. Windows folks may have different experiences. 

—Anna (NH6Z)

Bob Recny
 

What version of the ThumbDV do you have? Early units used 230.4kbps as default. While the FT230X can go up to 1Mbps, I'm not sure if those early units could handle rates above 230.4kbps.
Just checking - If you are using D2XX, have you removed any VCP (COM) Port drivers from your operating system for that device? D2XX and VCP drivers are mutually exclusive for the FTDI parts.

Wa4kfz
 

Something I ran into with my DV Stick (similar to the ThumbDV) was to operate my COM port with hardware flow control. I operate at 460800 and 8N1. Hardware flow control solved some of my weird dropout issues with the audio stream. 

73,
Mark wa4kfz 



On Jun 28, 2019, at 2:58 PM, Bob Recny <n8sqt@...> wrote:

What version of the ThumbDV do you have? Early units used 230.4kbps as default. While the FT230X can go up to 1Mbps, I'm not sure if those early units could handle rates above 230.4kbps.
Just checking - If you are using D2XX, have you removed any VCP (COM) Port drivers from your operating system for that device? D2XX and VCP drivers are mutually exclusive for the FTDI parts.

hayley@...
 

@Mark. I have set up RTS flow control. I am not sure if you are talking about something different. I always operate 8N1 for both the 230400 and 480600 and only the slower works. 
@Bob. The thumbDV is running with a linux 2.6.37 os and I do not believe there are any other COM port drivers.

I was able to find this old thread:
https://dvswitch.groups.io/g/main/topic/5521534#315
The observations he sees are the same I see when running the faster baud rate. I get a bunch of PKT_RDY packets with a few speech packets sprinkled in. The thread mentions something about the TI TPS380x-Q1 Voltage Detectors cause this hardware reset of the AMBE chip. Has anyone else run into this issue?

Annaliese McDermond
 

The observations he sees are the same I see when running the faster baud rate. I get a bunch of PKT_RDY packets with a few speech packets sprinkled in. The thread mentions something about the TI TPS380x-Q1 Voltage Detectors cause this hardware reset of the AMBE chip. Has anyone else run into this issue?
This indicates a hardware issue.  If there were a hardware issue, we'd have tons of folks complaining about bad hardware.  We have been selling the ThumbDV at 460800 for years now with no issues on Mac, Windows and Linux.