problem with sending data using RF module

**Archangel** · - 2nd April 2008, 16:49

Hello rano_zen06,
Looking at your code . . . not however, trying it out . . . Is this all of it? I do not see anything to cause the transmitter to send data from the keypad, unless I have become legally blind . . . or stupid . . . that is why I asked is this all of it. As I said . . I see empty variables in the serout routine.

Code:

 SEROUT TransmitterPIN,T2400,[Synk,Synk,9,Counter]

I would try adding a string to the serout routine for test purposes only, something like

Code:

SEROUT TransmitterPIN,T2400,$FE,1,["1 2 3 "]

**mister_e** · - 2nd April 2008, 16:54

Joe, seems you missed the underlined section...

Code:

Main:
HIGH LEDPin
PAUSE 100
LOW LEDPin
PAUSE 100

SEROUT TransmitterPIN,T9600,[Synk,Synk,Synk,Synk,Synk,Synk,9,Counter]

HIGH LEDPin
PAUSE 100
LOW LEDPin
PAUSE 100

Counter = Counter + 1
PAUSE 600
GOTO Main
END

**mackrackit** · - 2nd April 2008, 17:17

Maybe Joe has bifocals like me

**rano_zen06** · - 2nd April 2008, 19:09

Originally Posted by dhouston

As drawn, both Reset switches are shorting +5V to GND.

Can you provide details for your transmitter and receiver module
manufactiurer/model/pinouts?

See http://davehouston.org/RFTipsTricks.htm

Sorry for late reply guys,got a lot of homeworks to do. ; )
The fact is I have less information about my RF module.I just buy it from the nearest electronic store.Since I live here in Chiang Mai ,Thailand...It's hard for me to find a good types of RF module such as PArallax or TWS/RWS 434...For your reference I attach the picture of the RF modules .The link below may help. It was the datasheet of receiver chip used in my RF module.
http://www.himark.com.tw/images/pdf/...df/RX3310A.zip

Originally Posted by Joe S.

Hello rano_zen06,
Looking at your code . . . not however, trying it out . . . Is this all of it? I do not see anything to cause the transmitter to send data from the keypad, unless I have become legally blind . . . or stupid . . . that is why I asked is this all of it. As I said . . I see empty variables in the serout routine.

Code:

 SEROUT TransmitterPIN,T2400,[Synk,Synk,9,Counter]

I would try adding a string to the serout routine for test purposes only, something like

Code:

SEROUT TransmitterPIN,T2400,$FE,1,["1 2 3 "]

Actually what I want to do right now is display the counting numbers on my LCD at receiver board and it's nothing to do with my keypad.I just want to try send a data using my RF module first before I proceed with sending the data from my scanning keypad because I need to know if my RF module able to do it's job or not.

Originally Posted by mister_e

See pics in POST#1. 16F877A, and seems ADCON1 and CMCON settings are right.

Once the wire connection will work, i may suspect 2 other things.
1)open collector output of the receiver
2)use inverted mode instead. so the pin will idle low.

I already connect the Transmitter and the receiver pin directly but it's not work.my LCD only shows a bunch of black box .Maybe the major problem is from my coding or hardware??
Any other suggestion mister_e ? and how to use inverted mode??

**mackrackit** · - 2nd April 2008, 19:38

LCD only shows a bunch of black box

PIN 3 on the LCD is for contrast. Hook a pot up as a voltage divider with the wiper going to display pin #3. Then adjust until the black boxes go away. Then try sending "HELLO WORLD" to the display.

**mister_e** · - 2nd April 2008, 19:39

Hi, try a direct connection (porta to porta) with following. And of course don't forget to connect the Transmitter board GND with the Receiver board GND.

Receiver

Code:

        @       __CONFIG _HS_OSC & _LVP_OFF
        define OSC 20
        
        DEFINE LCD_DREG PORTC 'LCD data port
        DEFINE LCD_DBIT 0 'LCD data starting bit 0 or 4
        DEFINE LCD_RSREG PORTB 'LCD register select port
        DEFINE LCD_RSBIT 7 'LCD register select bit
        DEFINE LCD_EREG PORTB 'LCD enable port
        DEFINE LCD_EBIT 5 'LCD enable bit
        DEFINE LCD_RWREG PORTB 'LCD read/write port
        DEFINE LCD_RWBIT 6 'LCD read/write bit
        DEFINE LCD_BITS 8 'LCD bus size 4 or 8
        DEFINE LCD_LINES 2 'Number lines on LCD
        DEFINE LCD_COMMANDUS 2000 'Command delay time in us
        DEFINE LCD_DATAUS 50 'Data delay time in us
        
        TRISC = %00000000 'Set port B as output
        TRISB = %00000000 'Set port D as output
        low PORTB.6 'Set the R/W bit to low
        
        pause 1000 'wait until the LCD initializes
        
        INCLUDE "modedefs.bas"
        Counter VAR BYTE
        ReciverPIN VAR PORTA.0
        ADCON1 = 7 ' Alla digitala
        PAUSE 500

Main:
        SERIN ReciverPIN,T2400,[9],Counter
        GOSUB LCD
        GOTO Main

LCD:
        LCDOUT $FE,1
        LCDOUT $FE,$80,#Counter
        PAUSE 500
        RETURN

        END

Transmitter

Code:

        @       __CONFIG _HS_OSC & _LVP_OFF
        DEFINE OSC 20
        ADCON1=7
        ;CMCON = 7 'Alla I/O Digitala
        LEDPin VAR PORTB.4
        TransmitterPIN VAR PORTA.0
        INCLUDE "modedefs.bas"
        Counter VAR BYTE
        Synk VAR BYTE
        Synk = $55
        DEFINE CHAR_PACING 500
        Counter = 0
        
        HIGH TransmitterPin
        pause 200

Main:
        HIGH LEDPin
        PAUSE 100
        LOW LEDPin
        PAUSE 100
        SEROUT TransmitterPIN,T2400,[Synk,Synk,9,Counter]
        HIGH LEDPin
        PAUSE 100
        LOW LEDPin
        PAUSE 100
        
        Counter = Counter + 1
        PAUSE 600
        GOTO Main
        END

If you want to switch to the inverted mode, you just need to change T2400 to N2400, and the HIGH TransmitterPIN to LOW TransmitterPIN.

Work just fine here.

Unfortunately your picture don't help... it's a bit fuzzy

**rano_zen06** · - 3rd April 2008, 08:28

Originally Posted by mackrackit

PIN 3 on the LCD is for contrast. Hook a pot up as a voltage divider with the wiper going to display pin #3. Then adjust until the black boxes go away. Then try sending "HELLO WORLD" to the display.

thanks for the advice mackrackit.I've tested my LCD before and I found nothing's wrong with it.Even I connect pin 3 directly to the ground, my LCD still can display variable words clearly.

Originally Posted by mister_e

Hi, try a direct connection (porta to porta) with following. And of course don't forget to connect the Transmitter board GND with the Receiver board GND.

Receiver

Code:

        @       __CONFIG _HS_OSC & _LVP_OFF
        define OSC 20
        
        DEFINE LCD_DREG PORTC 'LCD data port
        DEFINE LCD_DBIT 0 'LCD data starting bit 0 or 4
        DEFINE LCD_RSREG PORTB 'LCD register select port
        DEFINE LCD_RSBIT 7 'LCD register select bit
        DEFINE LCD_EREG PORTB 'LCD enable port
        DEFINE LCD_EBIT 5 'LCD enable bit
        DEFINE LCD_RWREG PORTB 'LCD read/write port
        DEFINE LCD_RWBIT 6 'LCD read/write bit
        DEFINE LCD_BITS 8 'LCD bus size 4 or 8
        DEFINE LCD_LINES 2 'Number lines on LCD
        DEFINE LCD_COMMANDUS 2000 'Command delay time in us
        DEFINE LCD_DATAUS 50 'Data delay time in us
        
        TRISC = %00000000 'Set port B as output
        TRISB = %00000000 'Set port D as output
        low PORTB.6 'Set the R/W bit to low
        
        pause 1000 'wait until the LCD initializes
        
        INCLUDE "modedefs.bas"
        Counter VAR BYTE
        ReciverPIN VAR PORTA.0
        ADCON1 = 7 ' Alla digitala
        PAUSE 500

Main:
        SERIN ReciverPIN,T2400,[9],Counter
        GOSUB LCD
        GOTO Main

LCD:
        LCDOUT $FE,1
        LCDOUT $FE,$80,#Counter
        PAUSE 500
        RETURN

        END

Transmitter

Code:

        @       __CONFIG _HS_OSC & _LVP_OFF
        DEFINE OSC 20
        ADCON1=7
        ;CMCON = 7 'Alla I/O Digitala
        LEDPin VAR PORTB.4
        TransmitterPIN VAR PORTA.0
        INCLUDE "modedefs.bas"
        Counter VAR BYTE
        Synk VAR BYTE
        Synk = $55
        DEFINE CHAR_PACING 500
        Counter = 0
        
        HIGH TransmitterPin
        pause 200

Main:
        HIGH LEDPin
        PAUSE 100
        LOW LEDPin
        PAUSE 100
        SEROUT TransmitterPIN,T2400,[Synk,Synk,9,Counter]
        HIGH LEDPin
        PAUSE 100
        LOW LEDPin
        PAUSE 100
        
        Counter = Counter + 1
        PAUSE 600
        GOTO Main
        END

If you want to switch to the inverted mode, you just need to change T2400 to N2400, and the HIGH TransmitterPIN to LOW TransmitterPIN.

Work just fine here.

Unfortunately your picture don't help... it's a bit fuzzy

hi mister_e, I feel very sorry about the picture quality. I will attach the better one soon. Just try the code above but the error occur when I try to compile it using my microcode studio and it says " Error TRANSM~1.ASM 94 : [235] opcode expected instead of '0' "
After remove ' & _LVP_OFF ', microcode studio compile it succesfully.

The code works fine when I connect my transmitter and receiver pin directly and I can see the counting number display on my LCD.but It only works once when I try it using my RF modules.I got no result after try it the 2nd time.Only static number ( noise) shows up on my LCD.How do i reduce the noise??

**mister_e** · - 3rd April 2008, 15:50

There's a long long long way in between, i think you could try the Inverted mode first and then slow the baudrate, say 300bauds.

You should have a decent distance between the transmitter and receiver ... i think over 3 feets could be enough. Now , i don't know the RF receiver you have, but it's possible that it's output is an open-collector type. I would suggest you to add a 10K pull-up resistor between Vcc and RA.0 to see if it works better.

If you have any Scope, in the transmitter code, do a loop with SEROUT TransmitterPIN,N2400,[Synk] monitor the RF module output to see how good, bad the signal is.

On the transmitter AND the receiver module, use a 10-22uF tantalum+0.1uF as close as possible of your rf module. Same thing for your PICs. Try to sit your RF module away of your PICs.

You can also try to add 1-2 more Synk character at the begining of your transmission. For 1-2 bytes of data you shouldn't need any encoding/decoding even if.

Begin with it and see what happen. Without any spec of your module, it's a bit hard. Hope you have a scope

<hr>
For the compilation error, i used MPASM config fuse syntax, PM will use the following.

Code:

@      device HS_OSC, LVP_OFF

**mister_e** · - 3rd April 2008, 16:02

I'll also suggest you to follow Dave's post
http://www.picbasic.co.uk/forum/show...79&postcount=9

If the transmitter output signal is a bit messy, you will need to 'shape it'. Probably the internal comparator could be used here..

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