is hserin slow?

I am attempting to learn how to use serial communications
using the hardware serial port (16f627A) to receive a byte of data
but it seems to slow my program. The data looks clean (no noise).
I was expecting the hserin to quickly read the receive register.
can skip hserin and I read the rcreg directly? Do I need a interrupt?
Is there a better way?

DEFINE HSER_CLROERR 1 ' Automatically clear over-run errors
define HSER_BAUD 2400
RCIF VAR PIR1.5
command VAR
reponse VAR

loop:
if RCIF then
Hserin [command]
if command = 120 then
hserout [reponse] ' respond with data
endif
gosub refresh segment display
gosub read keypad

goto loop

or

loop:
if RCIF then
command=rcreg
if command = 120 then
hserout [reponse] ' respond with data
endif
gosub refresh segment display
gosub read keypad

goto loop



Thanks,

Mark

You forgot DEFINE TXSTA and DEFINE RCSTA stuff. But indeed you can read RCREG directly of course you can. will it be faster??? can't say.
Here's a link for you
http://www.picbasic.co.uk/forum/show...1&postcount=11

Thanks Steve!

Is RCREG 2 bytes?
I only have 1 byte to send, Should I always send 2 bytes
and always read 2 bytes?

Thanks,

Mark

Hi,

I think that RCREG can only "hold" 2 bytes.
If you don't retrieve your data before that 3rd byte comes along, you get an overrun or something. It probably just kicks the first byte it received "off the end".

:)

YUP! RCREG is a 2 byte buffer. This help to miss character.
You don't need to read always 2 bytes ... well yes and no. Just make a check if the RCREG is now empty will suffice.

and you just need to send 1 bytes at the time as TXREG is a single 1 byte register.

HTH

Here is a couple attached demo programs that might help,written for the 16F877.Modify for you needs.One uses the on interrupt command and the other the interrupt flag.

Thank You all!

I was frustrated and a little weary but your suggestions were
timely and very helpful. My serial communications are working now.

Reading RCIF & RCREG appear much faster than HSERIN.

Thanks,

Mark

It's like many built-in function.
HSERIN/HSEROUT
HPWM
ADCIN
are some in the list. When you need for speed, the best way is still acess the internal register. It also produce tighter code. Built-in function are great when you don't want to break your nuts with data handling and ... and ... and.. well you know what i mean ;)