why does the uart transmite need to delay sometime

Forum: No OS
noosman 
I write a program:pc send a char to the uart,afer the uart receive it it
tarnsmite the char back ,but  if I dont deay for sometime ,it seems that
cant tarnsmite,just as the pic
http://www.baidupcs.com/thumbnail/d9446ad3306ce9518a32001d7f9112e8?fid=1...

my code are as fllowing
。。。。。。
Main.c
。。。。。。
http://www.baidupcs.com/thumbnail/06e1990dba5a8bc4f6de819078dd05f4?fid=1...

。。。。。
uart0.c
。。。。。
http://www.baidupcs.com/thumbnail/e42e1ae44cd379b4f860685b66e91a39?fid=1...

。。。。。
uart0.h
。。。。
http://www.baidupcs.com/thumbnail/8505d19ccbc24594b669f72aa10526b2?fid=1...

BUT IF I ADD THE DELAY,IT WORKED OK!DOES anyone know wheres the problem

davef 
none of the links work.

RS232 or RS485?

noosman 
OK,how about now
the uart transmit and receive pic
https://farm9.staticflickr.com/8241/8594417594_071b883a66_z.jpg

.......
Main.c
.......
https://farm9.staticflickr.com/8106/8594417646_c3fd789c67_z.jpg


......
uart0.c
.......
https://farm9.staticflickr.com/8369/8593317495_7913fde0ff_z.jpg

davef 
You didn't answer my question.

noosman 
Errr,Im sorry,RS232,does this matter??
before I use it on the MSC51(AT89C52),it worked ok,I feel puzzled why the
ARM9 not.Is ARM's handling speed slower than
MSC51????????????????????????????????????????????????????????????????????????

davef 
I have seen issues on a RS-485 system that was "fixed" using a delay. 
Setting up the USART interrupts correctly is the proper way to sort the
problem.  

Next, how have you set flow control?

I don't think you will have a problem with 115200 baud on this platform. 
As far as max capability is concerned remember you have an operating system
trying to work along side of your serial comms. 

Also, this is a 32 bit uP not like your MSC51 which is 8 bits.  What is the
max clock frquency for your MSC51.  All your MSC51 is doing is serial comms
as I doubt your are running an RTOS or OS on it.

noosman 
Yeah,Im sure my intterrup setting is Ok,see here(only transmite)
https://farm9.staticflickr.com/8385/8594080269_3f0a78b78e_o.jpg

I dont use flow conrol,so setting this in the uart assistant
https://farm9.staticflickr.com/8365/8595180248_52c0cdbf42_o.jpg

Im very gloomy about this but I dont hv a simulation such as JLINK,OPENJTAG

davef 
What happens if you reduce the baud rate to next lower option?

noosman 
@davef 
the problem is still the same,Maybe I should buy a jlink

davef 
Are you able to use a remote terminal into the target?