Frequently Asked Questions

Q. What Baudrates does the USB to TTL Cable support ?
A. The USB to TTL Cable supports the following baudrates (standard windows baudrates are in bold):

300, 600, 1200, 1800, 2400, 4000, 4800, 7200, 9600, 14400, 16000, 19200, 28800, 38400, 51200, 56000, 57600,  64000, 768000, 115200, 128000, 153600, 230400, 250000, 256000, 500000, 576000, 921600

We can also provide custom Baudrates for specific applications, however we reserve this option for quantity orders only.

Q. Can I connect the TTL Cable to +3/+3.3v microcontrollers ?
A. Yes if the RX input of the microcontroller is +5v tolerant (please check the absolute Max pin input level) otherwise the RX line voltage should be reduced using a potential divider with values of 22k and 33k.  The threshold for the TX is such that +3v/+3.3v logic will have no problem in transmitting.

Q. My computer seems to 'hang' when I using some software (e.g. Atmel FLIP)
A. Unfortunately this is true with our original batch of cables when the PC software requires the use of 2 stop bits.  Cable from bought from us after October 2005 has this issue fixed. 
[Please note however that Atmel have updated their software to run with 1 stop bit and therefore can be used with all our cables!]

Q. Do you have example software how we can get the number of the com-port the USB2TTL uses (from registry? device manager list?) If possible in MFC, C++ or even VB.
A. Click Here for some C and VB code that searches the Registry for the assigned COM port number(s).

Q. Which COM port is my USB to TTL Cable ?
A. Click Here for details on how to find the Com Port Number

Q. Can I change the COM Port that Windows Assigns to my USB to TTL Cable ?
A. Yes, Click Here for details on how to change the Com Port Number.

Q. During the installation of the device I get the following error:  "cannot find the file specified"
A. Windows 2000/XP has a bug that it cannot properly detect new hardware by *.inf files, if the RunOnce registry key is missing from the following location:  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
This key is often used by installers to execute post-reboot programs, but sometimes they accidentally delete this key.
Go to Start » Run and enter "regedit."
Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
With CurrentVersion Highlighted, go to the Edit menu and select New » Key
Name the key RunOnce, leaving everything else about the key alone.
The RunOnce key should now exist underneath the CurrentVersion key.


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