|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,
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
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.
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
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.
I get the following error: 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:
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."
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.