Data Logging - Aliasing 9600 to 8192 Baud

Hey guys,

No info to be found, so just thought I'd do a quick write-up for everybody about aliasing the FTDI COM Port @ 9600 baud (or whichever you choose) to receive 8192 baud. I was tired of seeing all of the error packets in my log files and sought out to fix it.

I use an FT232RL breakout board for logging, and don't own a Moates logger, but seeing as they use FTDI chips it should work for them as well.

This will correct the mismatch from 9600 baud (85.33% efficiency) to 8191.12 baud (99.99%). I've tested it myself, and only received 1 error packet during 45 minutes of logging with TunerPro RT.

The long of it can be read from FTDI's Application Note AN_120, Aliasing VCP Baud Rates. I'll skip the math, shorten it, and just tell you how to do it with a little explanation along the way.


NOTE: Done in Windows 10, but should be similar for earlier operating systems

*DO THIS AT YOUR OWN RISK*This requires making a change in the Windows registry using RegEdit. Any other changes to the registry can mess up your Windows installation.

-------Additional Info--------
The FTDIPort.INF driver file installed contains a string of hex values that sets the standard baud rates. The line for them is as follows:

[FtdiPort.NT.HW.AddReg]
HKR,,ConfigData,1,01,00,3F,3F,10,27,88,13,C4,09,E2 ,04,71,02,38,41,9c,80,4E,C0,34,00,1A,00,0D,00,0 6,40,03,80,00,00,d0,80

These are the baud rate configurations. I've made the bytes of interest in bold (keep in mind, you can change any of the following values to your desired baud rate, in this case 8192):
10,27 => divisor = 10000, rate = 300
88,13 => divisor = 5000, rate = 600
C4,09 => divisor = 2500, rate = 1,200
E2,04 => divisor = 1250, rate = 2,400
71,02 => divisor = 625, rate = 4,800
38,41 => divisor = 312.5, rate = 9,600
9C,80 => divisor = 156.25, rate = 19,200
4E,C0 => divisor = 78.125, rate = 38,400
34,00 => divisor = 52, rate = 57,692
1A,00 => divisor = 26, rate = 115,384
0D,00 => divisor = 13, rate = 230,769
06,40 => divisor = 6.5, rate = 461,538
03,80 => divisor = 3.25, rate = 923,076
00,00 => RESERVED
D0,80 => divisor = 208.25, rate = 14,406

-----------------------------------


Start off by opening Device Manager with your data logger plugged in. It should be visible under Ports (COM & LPT). Right-click the correct USB Serial Port, and go into the Properties menu.

Under the Details tab of the device properties, change the Property drop-down box to Device instance path. The FTDI device ID for your programmer is here, i.e., FTDIBUS\VID_0403+PID_6015+DN05K0BRA\0000

Attachment 13985

For Windows 7+, open the Start menu and type "RegEdit". Open the registry editor from here.
For pre-Windows 7 systems, click Start -> Run... and type "regedit" into the dialog box.

In the left folder pane, navigate to the following path:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\F TDIBUS\

In this folder, expand the correct folder for your programmer's ID (there may only be one), and its sub-folders 0000\Device Parameters, i.e.:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\FTDIBUS\VID_0403+PID_6015+DN05K0BRA\0000\Device Parameters.

The ConfigData binary value contains the previously mentioned hex values. Double-click to modify it.

In the modify window, find the two bytes

38,41 (for the 9600 baud slot).
Replace these values with 6E,81.

(according to the FTDI application note: 3000000 / 8192 = 366.21 =~ 366.25, 366 hex = 16E, add .25 sub-divisor = 816E = 6E,81)

Attachment 13986 Attachment 13987

Save/close RegEdit, restart, and you should be all set! 9600 baud will now be 8191.12 baud.

***IMPORTANT NOTE***
The value in the drop-down box in Device Manager - COM Port properties will still say 9600, but the modified value will be applied. For example, if you changed the 600baud value

88,13

to our modified 6E,81, 600 will remain, but will actually be 8191.12.



Thanks, and good luck!