I am using the FTDI driver with a 8U232AM.
I have noticed the following issues:
Above 115.2K there are buffer overflows and dropped characters.
At 115.2K, I haven't seen any dropped characters but have seen the
following:
VFS: Mounted root (romfs filesystem) readonly.
Mounted devfs on /dev
Freeing unused kernel memory: 48k freed
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿserial console detected. Disabling virtual terminals.
console=/dev/console
init started: BusyBox v0.49 (2001.02.15-17:54+0000) multi-call binary -- GPL2
This is a serial console conected to an 8U232AM device using minicom to
view the serial console.
There is no data lost here, but there is a bunch of what appears to be
255 characters inserted as if something wrapped over itself or
something. This never happens when using a native UART to view the
serial console.
I have also once seen about a 4 second delay at the above problem point
and one other time that I hadn't previously attributed to the FTDI
device and/or driver.
At this point I don't have anything to contribute other than a problem
report.
Also, I did some latency testing on the device using a loopback. I
modified the kernel for 1024Hz scheduling and ran a posix
realtime process that would send a bunch of characters and see how long
it took for them to come back.
I found that a native UART has a latency of 1-2ms for a single byte.
That latency increases with packet size. When run over the 8U232AM
the 1 byte latency is about 16-17ms and remains about 15ms longer than
the native UART for larger packet sizes. Is this latency somehow
tunable?
Thanks!
Ty
--
Tyson D Sawyer iRobot Corporation
Senior Systems Engineer Real World Interface Div.
[EMAIL PROTECTED] Robots for the Real World
603-532-6900 ext 206 http://www.irobot.com
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