Wireless problem

[Jerson]

There are a couple of things I can think of.

Try increasing the preamble bytes $55. So, you send $55,$55,$55,$55,$55,$66,[data]
Try flagging the capture of qualifier in receive module to the LCD. So, you know if it is being captured correctly.
Perhaps the most important to me. Try keeping the transmitter on continuously till you get the receive part working correctly. Maybe the switching on/off of the transmitter is causing the receiver to go crazy.

[mister_e]

all good point, but this doesn't explain why the PC comm always works.

EDIT: have to be a paste error, but DEFINE OSC have to be in capital letter, unless... well i guess nothing would even works anyways...

[supersonic]

There are a couple of things I can think of.

Try increasing the preamble bytes $55. So, you send $55,$55,$55,$55,$55,$66,[data]
Try flagging the capture of qualifier in receive module to the LCD. So, you know if it is being captured correctly.

2 more preamble bytes!!!! Now I send $55,$55,$55,$55,$66,data and the amount of correct data received(and displayed on lcd) is more than 90%

I've also made a few changes: there is now a 5msec pause after the txer is switched on. 2400bps now works fine.

On the monitoring side I chenaged the hardware/software tools used. At first I tried a software called serial port monitor and the hardware was a max232 ttl<->rs232 transceiver.

Now I use a 2 resistor based rs232 adapter and the serial communicator software built into MicroCode Studio.
What I found is that now I can see the noise!!! There is a lot of junk along with correct data. Maybe the other software/hardware configuration were filtering that noise so I could only see correct data...

So I thought that adding more preamble could be an initial solution... it worked!
I will try the reliability of the communcation at longer distance to see if I need to add manchester routines...

[Ioannis]

That test results clearly show that the turn-on delay is absolutely necessary. Why not give your Txer more time to wake-up?? Say 100ms and test how it goes. Then you can decrease this wake-up time gradually.

Also if you send a long stream of preamps and only 1 or 2 data bytes, that is OK. No manchester is really necessary. But more than this... don't think whether to or not to. Just add it.

More, I would suggest for 100% reliable communication to add checksum or even better a CRC check.

Almost every receiver will output noise that could lead to false data reception when no transmission takes place. There is no mute function available on these cheap devices.

Ioannis

[supersonic]

Now that I solved(or going to solve...) reliability problems, I find that serin/serout work fine while hserin/hserout seem to have more problem...

Usart has been configured used pic multicalc.

I noticed that Mister_E adds the comment "Enable serial port & continuous receive" setting rcsta receiver.
Does it mean that hserin does not have to be in a loop? maybe something like:

hserin [#txpin]

main:
  lcdout $fe,row1,dec txpin
goto main

could work?

[Ioannis]

If you use the example you post, then you will display only the first byte and continue to display that exact byte endlessly.

If you send serial data then the buffer of the 2-byte long USART will overflow and depending on the setup will stop with error flag raised or replace old bytes with the new ones.

Please refer to your Data sheet of the PIC you are using for more infos about the USART and its associated flags and control bits.

If serin/serout work then I am sure that USART will work better and without having PIC to deal with the data untill they are available to process. You must have something wrong with your setup.

As Steve stated without the whole picture we can only guess.

Here in Greece we had the ancient times the oracle at Delphi and Pythia making guesses and prophecies but nowadays I suppose it is better to see, measure calculate and then conclude. So if you want real help post all you got (schematics, cablings, software, defines etc).

Ioannis

[supersonic]

If you use the example you post, then you will display only the first byte and continue to display that exact byte endlessly.

As the define comment says "continous receive" I guessed it could've be continuos receive in background while pic runs the program, as hpwm.

If you send serial data then the buffer of the 2-byte long USART will overflow and depending on the setup will stop with error flag raised or replace old bytes with the new ones.

I included DEFINE CLROERR 1 to clear overflow automatically.
And surely I still have to study a lot....

[supersonic]

Finally!

At last I've been able to use USART!
On the tx side I changed serout from N2400 to T2400 and the rx started to display correct data! Data is sent 10ms after powering the txer.

99% of data is correctly showed on the display.

Now I have to mount the sensor and send acquired data along with a sort of checksum.

I could stay hours watching the display:0...1...2...3...4..... to see if some of my numbers gets lost. Watching it for a minute, no problems!
So here is the working code for the TX:

INCLUDE "modedefs.bas"

ANSEL=0
CMCON0=%00000111

define osc 4
txpin   var gpio.4
led     var gpio.5
power   var gpio.2
i       var byte

low power

loop:
    for i=0 to 9
      high power
      pause 10
      serout txpin,t2400,[$55,$55,$55,$55,$66,#i]
      low power
      high led
      pause 30
      low led
      pause 1000
    next i
goto loop

And, of course RX:

define  OSC 20
Define 	LCD_LINES	4			' Settings for a 4x20 LCD
Define	LCD_DREG	PORTB		'   4bit mode
Define	LCD_DBIT	4			'
Define	LCD_RSREG	PORTB		
Define	LCD_RSBIT	3		 	
Define	LCD_EREG	PORTB'      
Define	LCD_EBIT	2

DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 20h ' Enable transmit, BRGH = 0
DEFine HSER_BAUD 2400
DEFINE HSER_CLROERR 1 ' Clear overflow automatically

'LCD Lines constants
row4        con	$d4
row3	    con	$94
row2	    con	$c0
row1	    con $80
hser var byte

intcon=0

pause 500
lcdout $fe,1
lcdout $fe, row1, "** RX TEST **"

loop:
      hserin [wait($66),hser]
      hserout [#hser]
      lcdout $fe, row3," hser: ",dec1 hser
goto loop