16f88 ausart & defines

[retepsnikrep]

My application requires use of the hardware usart ports for background serial comms.

Problem is I need 9600,8,N,1 for Tx and 9600,8,E,1 for Rx

So need 9 bit mode for RX and 8 bit mode for TX.

I was going to use Hserout but note the defines affect both Hserin & Hserout

Any ideas?

Can I poke the RCSTA & TXSTA registers just before I use Hserin or Hserout to change
from 8bit to 9 bit mode etc without corrupting anything Hserin/Hserout wants to do?

I can't use Serin2 as i have some interupts going on which interfere with the Serin2 operation.

[mackrackit]

You do not need to set the DEFINES at the beginning of your code. You can set the registers as you go. I would setup a couple of sub routines for this.

[retepsnikrep]

The code I use at present for the 9600,8,E,1 reception is

DEFINE HSER_BAUD 9600		'Set Baud rate to 9600bps
DEFINE HSER_BITS 9		'Set to 9 bit mode
DEFINE HSER_EVEN 1		'Set Even Parity
DEFINE HSER_CLROERR 1 		'Clear overflow error automatically

HSERIN [WAIT($87), STR BCMDATA\11]	'Wait for packet start $87 then Rxd 11 bytes into BCMDATA

The code i use for the 9600,8,N,1 Transmission is

DEFINE HSER_BAUD 9600		'Set Baud rate to 9600bps

HSEROUT [254,192,"Cruise ",#Cruise," Duty ",#DutyCycle]	'Display

Both the above work fine in seperate programs, my program now needs to combine them into one and swap between one and the other
during execution.

So receive some data with parity, process it, then spit it out without parity and repeat.

Could you help with an example? Your subroutine? Or what registers to change?
I need to use hserin/out if i can as i can understand it and i'm working with arrays for the rxd data!!

[mackrackit]

If you have not been using mr. E's PicMulticalc grab it over here.
http://www.picbasic.co.uk/forum/cont....-PICMultiCalc

Quick example of not using DEFINES.
MultiCalc gives this for 9600 Baud at 20Mhz:

RCSTA = $90 ' Enable serial port & continuous receive
TXSTA = $24 ' Enable transmit, BRGH = 1
SPBRG = 129 ' 9600 Baud @ 20MHz, 0.16%

So the code would be something like this:

Send_Data: 'Sending Sub
RCSTA.4 = 0 : RCSTA.4 = 1
RCSTA=$90:TXSTA=$24:SPBRG=129:HSEROUT[254,192,"Cruise ",#Cruise," Duty ",#DutyCycle]
RETURN

Because DEFINES are not used you can change things around at will. Just do the changing in Sub-routines then GOSUB when ever needed.

[HenrikOlsson]

Hi,
I'm currently working on something similar and have been thinking about this for a while. I'm afraid (though I DO wish I'm wrong) that it's not as easy as just setting the registers manually.

Yes, you can control the way the (E)USART operates and enable it to send and/or receive 9 bits but the problem is that the DEFINE HSER_EVEN 1 and HSER_BITS 9 not only controls those registers, it also controls the way PBP generates the code.

When using parity PBP has to calculate the parity bit for each byte it sends and "load" that bit into the TX9 location of the TXSTA register. (And similar for the RX-part of course). If you don't DEFINE HSER_EVEN PBP doesn't calculate the parity bit so simply enabling 9 bit transmision and/or reception by setting up RXSTA and TXSTA properly isn't enough I'm afraid.

My personal project involves allowing the enduser to select between using parity or not which means it has to be done at runtime - not at buildtime.

Looking forward to a disussion and hopefully a solution!

/Henrik.

[mackrackit]

You might be correct, to be honest I do not use 9 bit that often so that may be the problem. I do use the register thing other wise. I had e a project a few years ago where the Baud needed to be changed on the fly.

I am looking at PBPPI18L.LIB. I think the 9 bit stuff is done in hardware. Looks to me changing the RCSTA or TXSTA values is all that is needed???

ifndef HSER_BITS
HSER_BITS = 8 ; Default to 8 bits
endif
ifndef HSER_RCSTA ; Receive register data
if (HSER_BITS != 9)
HSER_RCSTA EQU 90h ; Receiver enabled
else
HSER_RCSTA EQU 0d0h ; Receiver enabled for 9 bits
endif
endif
ifndef HSER_TXSTA ; Transmit register data
if (HSER_BITS != 9)
HSER_TXSTA EQU 20h ; Transmitter enabled
else
HSER_TXSTA EQU 60h ; Transmitter enabled for 9 bits
endif
endif

I guess someone will have to give it a try...