[Lazarus] SdpoSerial Tx and Rx buffers?

[Bo Berglund]

On Fri, 18 Feb 2011 09:11:14 +0100, Michael Schnell
<mschnell at lumino.de> wrote:

>On 02/17/2011 05:46 PM, Bo Berglund wrote:
>>
>> At least in the embedded world UART:s have *both* a transmit and
>> receive FIFO.
>Same with PCs. And AFAIK, the OS-driver adds a huge Fifo buffer in both 
>directions to allow for the quite latency userland software to work as 
>good as possible without degrading the transmission performance.
>

But then we have the problem I have already detected when test running
my SdpoSerial based application:
If I set it up to send a large chunk of data and put a breakpoint at
the WriteData call so I can time the process when I click step-over I
see this:
Data size 100.000 bytes
Baudrate: 38400
Estimated shortest time for transfer: 26 s
Time to return from call: about 30 s

So this means that even if the OS has a "huge" buffer for outgoing
data it fails to improve the call time of the blocking call to
WriteData.
My initial question was about adjustment of the size of the transmuít
buffer such that I could ensure safe transfer of the data and snappy
response in my application.
As it is now the GUI will die when the transfer is made.
I have to somehow adapt to this fact and add a buffer layer myself in
a thread that feeds data to the WriteData method.

-- 

Bo Berglund
Developer in Sweden