GLK12232 and RS232 Communication project

LK/ELK/VK/PK/OK/MX/GLK/EGLK/GVK/GLT Series

Moderators: Henry, Mods

Post Reply
Dexter
LCD Geek
Posts: 49
Joined: Wed Aug 15, 2001 6:00 pm
Location: Chicago
Contact:
Contact Dexter

GLK12232 and RS232 Communication project

Post by Dexter »

well, im back on the horse to trying to get my big PIC project working.
I was going to use the GLK on the PIC's I2C bus, but I figured it would be better to first get it going on the PIC's internal USART.

So, I got the PICs USART talking to my PC perfectly. Connected to COM1, 19.2k, 8N1, no flow control. Press a button, and "Hello" appears on my HyperTerminal.

I hooked up the GLK to COM2, opened up a HyperTerminal Session. 19.2k, 8N1, no flow control. Typed a couple letters. "asdf" appears on my LCD. excellent.

So i hooked up the PIC directly to the LCD, but nothing will show up. What happens is contrast of the screen goes up a bit. Shouldn't I be seeing "Hello" display on my LCD? I don't understand...if the PIC can talk to my PC port, and the PC can talk to the LCD, shouldn't the PIC be able to talk to the LCD?

The PIC is a 16F877 on a Microchip PICDEM2 Plus demo board, with MAX232A installed on it for serial communication.

I have a 1 millisecond delay between each character send. I've tried 5ms, but haven't tried no delay yet.

The only other thing I can think of would be the PIC to LCD cable...but...I am pretty sure it is working.

One last thing, it seems the GLK is trying to send some data back to the PIC for some reason. I have my PIC programmed to display on LEDs any data recieved, and after I send anything to the GLK, I get some data back. It flashes too fast for me to get it all, but the last byte of data is "00001010". I don't know if that means anything. It doesn't make sense, because when you send data to the GLK via PC/Hyperterminal, you don't get anything back

If anyone has any ideas or links to some places that have used this LCD in conjunction with a PIC, please post them.

Thank you :)
Top
Henry
OMNIPRESENT
OMNIPRESENT
Posts: 3014
Joined: Tue Aug 14, 2001 6:00 pm
Contact:
Contact Henry

Post by Henry »

PIC ---> PC no problem
PC ---> LCD no problem
PIC ---> LCD problem

Correct?
Last edited by Henry on Sun Dec 01, 2002 11:25 pm, edited 1 time in total.
Henry J.
President
Matrix Orbital
Top
Henry
OMNIPRESENT
OMNIPRESENT
Posts: 3014
Joined: Tue Aug 14, 2001 6:00 pm
Contact:
Contact Henry

Post by Henry »

post some of your code when you talk to the LCD...
Henry J.
President
Matrix Orbital
Top
Dexter
LCD Geek
Posts: 49
Joined: Wed Aug 15, 2001 6:00 pm
Location: Chicago
Contact:
Contact Dexter

Post by Dexter »

Henry wrote:post some of your code when you talk to the LCD...

Code: Select all

        list p=16F877
	Title "USART Demo Program"
;
;This program runs on the PICDEM-2 demo board.
;In the Demo board, Port B is connected to 8 LEDs. 
;When the PIC16F877 receives a word of data from
;the USART, the value is displayed on the LEDs and
;is retransmitted to the host computer.
;
 include <P16F877.INC>
 __CONFIG _CP_OFF & _WDT_OFF & _XT_OSC & _PWRTE_ON & _LVP_OFF 
CBLOCK 0x20
COUNT, DELAY,DELAYTMP,			; delay function variables...

 ENDC
 
 
 DELAY_MILLI macro TIME
  movlw TIME
  movwf DELAY
  call DELAY_MS
  endm

DELAY_MICRO macro TIME
  movlw TIME
  movwf DELAY
  call DELAY_US
  endm

SEND macro CHAR
	movlw CHAR
	movwf TXREG
	DELAY_MILLI 5
	endm

GREET macro  
	SEND 'H'	;call send macro, pass it H
	SEND 'e'
	SEND 'l'
	SEND 'l'
	SEND 'o'
	endm

;
	org	00h		;Reset Vector
	goto	Start
;
	org	04h
	goto	IntVector

    org     05h		;Beginning of program EPROM
    
;----------------------------------------------------------------------------------------
; Subroutines
;----------------------------------------------------------------------------------------
DELAY_US					; busy wait of DELAY us
						; 200ns instruction period assumed
  nop						; (1)
  nop						; (2)
  decfsz DELAY,f				; test DELAY count (3)
    goto DELAY_US				; loop if not done (4,5)
  return					; gtfo (4,5)

DELAY_MS					; busy wait of DELAY ms
						; dependant upon DELAY_US being accurate
  movf DELAY,w
  movwf DELAYTMP				; save DELAY time
DELAY_MS_LOOP					; inner loop
  movlw 245					; load 245 (1)
  movwf DELAY					; into DELAY (2)
  call DELAY_US					; wait 245us (3-249)
  movlw 245					; load 245 (250)
  movwf DELAY					; into DELAY (251)
  call DELAY_US					; wait 245us (252-498)
  movlw 245					; load 245 (499)
  movwf DELAY					; into DELAY (500)
  call DELAY_US					; wait 245us (501-747)
  movlw 246					; load 246 (748)
  movwf DELAY					; into DELAY (749)
  call DELAY_US					; wait 246us (750-997)
  decfsz DELAYTMP,f				; test DELAYTMP count (998)
    goto DELAY_MS_LOOP				; loop if not done (999,1000)
  return					; gtfo (999,1000)

Start
    clrf    PORTB           ;Clear PORT_B output latches
	bsf		STATUS,RP0
	movlw   b'00000001'
	movwf   TRISB 		;Config PORT_B as all outputs
	movlw	b'00100000'	;Enable RCIF interrupt
	movwf	PIE1
	movlw	0Ch		;19200 baud @4MHz
	movwf	SPBRG
	movlw	b'10100100'	;Async, High baud rate
    movwf	TXSTA
	bcf	STATUS,RP0
	
	movlw	b'10010000'	;Enable continous reception
	movwf	RCSTA
	movlw	b'11000000'	;Enable global interrupts
	movwf	INTCON
 
    GREET	; greetings message
   
Loop
	goto	Loop ;wait for recieve interrupt

IntVector
	movlw	06h		;Mask out unwanted bits
	andwf	RCSTA,W		;Check for errors
	btfss	STATUS,Z	
	goto	RcvError	;Found error, flag it

	btfss	PIR1,5		;Check for data ready
	retfie			;Some other interrupt, exit
	
	movf	RCREG,W		;Get input data
	movwf	PORTB		;Display on LEDs
	movwf	TXREG		;Echo character back
    movlw	h'0D'
    movwf	TXREG
    movlw	h'0A'		;newline
	movwf	TXREG
	retfie	

RcvError
	bcf	RCSTA,4		;Clear reciever status
	bsf	RCSTA,4
	movlw	0FFh		;Light all LEDs
	movwf	PORTB		
	retfie
	
	end
Top
Dexter
LCD Geek
Posts: 49
Joined: Wed Aug 15, 2001 6:00 pm
Location: Chicago
Contact:
Contact Dexter

Post by Dexter »

basically, i press the reset button on the PICDEM2 board to send the data.
Top
Henry
OMNIPRESENT
OMNIPRESENT
Posts: 3014
Joined: Tue Aug 14, 2001 6:00 pm
Contact:
Contact Henry

Post by Henry »

you have to make it hard for me here don't you, can't use C or C++... :o

I will get the head engineer to look at it tomorrow morning with me... unless some one with assembly know how comes by...
Last edited by Henry on Sun Dec 01, 2002 11:44 pm, edited 1 time in total.
Henry J.
President
Matrix Orbital
Top
Dexter
LCD Geek
Posts: 49
Joined: Wed Aug 15, 2001 6:00 pm
Location: Chicago
Contact:
Contact Dexter

Post by Dexter »

Henry wrote:you have to make it hard for me here don't you, can't use C or C++... :o

I will get the head engineer to look at it tomorrow morning with me... unless some one with assebly know how comes by...
heheh i dont have any C/C++ compliers for PICs. sorry about that, heh.

thanks for the superfast response though! :)
Top
Henry
OMNIPRESENT
OMNIPRESENT
Posts: 3014
Joined: Tue Aug 14, 2001 6:00 pm
Contact:
Contact Henry

Post by Henry »

I'm up.. not sure why, but I am :) I haved used the CCS compiler of the PIC... and I have a ICE here, very nice to have... but the CCS compliler is a pain in the but, not following any rules, and some times you end up having problems because a long isn't really a long... :roll:
Henry J.
President
Matrix Orbital
Top
Dexter
LCD Geek
Posts: 49
Joined: Wed Aug 15, 2001 6:00 pm
Location: Chicago
Contact:
Contact Dexter

Post by Dexter »

ive tried CSS i think...maybe Hitech PICC or something...something you had to pay for and something i only had the demo of.

what is an ICE?
Top
Henry
OMNIPRESENT
OMNIPRESENT
Posts: 3014
Joined: Tue Aug 14, 2001 6:00 pm
Contact:
Contact Henry

Post by Henry »

CCS costs money and then you have to pay for patches, and he generaly ends up breaking something with the patch, so youhave to wait till the next patch, read their forums, it's almost comical...

Image

it's a pic emulator, all you do is attach a pod to the development board, and then just run your software on the PC and it emulates the PIC...
Henry J.
President
Matrix Orbital
Top
Dexter
LCD Geek
Posts: 49
Joined: Wed Aug 15, 2001 6:00 pm
Location: Chicago
Contact:
Contact Dexter

Post by Dexter »

See, i have RS232 communication and I2C bus working now
temp sensor is Microchip TC74A5

Image

now id just like to get it up on my GLK :D
Top
Henry
OMNIPRESENT
OMNIPRESENT
Posts: 3014
Joined: Tue Aug 14, 2001 6:00 pm
Contact:
Contact Henry

Post by Henry »

Switch your Rx and Tx lines...
Henry J.
President
Matrix Orbital
Top
Dexter
LCD Geek
Posts: 49
Joined: Wed Aug 15, 2001 6:00 pm
Location: Chicago
Contact:
Contact Dexter

Post by Dexter »

Henry wrote:Switch your Rx and Tx lines...
tried that


when the LCD is connected to the PIC, it seems like it "locks" the PIC up.

I have an LED set to turn on at powerup. with no LCD connected, it turns on fine. Whent he LCD is connected, the LED doesnt turn on. if i disconnect the LCD, reset the PIC so the LED comes on, and then plug the LCD in, it will turn off and just sit there.
Top
Henry
OMNIPRESENT
OMNIPRESENT
Posts: 3014
Joined: Tue Aug 14, 2001 6:00 pm
Contact:
Contact Henry

Post by Henry »

Are you working on TTL levels or RS232 levels on the PIC and the GLK?

{edit} well, of course you are talking to the LCD at RS232 level, since you can talk to it from the computer... now the question is, are you talkingto it at TTL levels from the PIC?
Henry J.
President
Matrix Orbital
Top
Dexter
LCD Geek
Posts: 49
Joined: Wed Aug 15, 2001 6:00 pm
Location: Chicago
Contact:
Contact Dexter

Post by Dexter »

Henry wrote:Are you working on TTL levels or RS232 levels on the PIC and the GLK?

{edit} well, of course you are talking to the LCD at RS232 level, since you can talk to it from the computer... now the question is, are you talkingto it at TTL levels from the PIC?
im not sure what you mean...

PIC - TTL -> MAX232A -> RS232 - LCD

an idea just popped into my head...i think it has to do with the cable, possibly some pins need to be grounded/connected to each other...i will experiment
Top
Post Reply

Return to “LK/ELK/VK/PK/OK/MX/GLK/EGLK/GVK/GLT”