Is it possible to interpret non-standard serial data with PicBasic (sample attached)

[tumbleweed]

IF PORTC.4=1
or
IF PORTC.4=0

makes corresponding pin high or low?

I highly doubt that. I don't know how you're testing it, but if that's the case things are seriously broken.

You likely have some other issue.

[HenrikOlsson]

The IF statement per se should not and I'm pretty sure does not twiddle the pin but if what you you're doing is somehing like...

If PortC.4 = 0 THEN
   PortC.1 = 1
ENDIF

...and there happens to be analog functions on the pins which you haven't disabled then the actual state of PortC.4 isn't read correctly and you're getting into the classic RMW issue where the "invalid" state of PortC.4 is being written back to PortC.4 when the write operation to PortC.1 occurs but without seeing the rest of the code it's hard to say for sure.

/Henrik.

[CuriousOne]

Here is the complete code:

Include "modedefs.bas"  ' Include serial modes
   TRISA = %11111111       ' Set PORTA to all input
       TRISC = %00000000	    ' Sets all PortB pins to output
   ADCON1 = %10000101      ' Set PORTA analog and right justify result
   ADCON0=%00000000
   low portc.4
   low portc.5
   
X   VAR PORTC.4 

DEFINE LCD_DREG PORTB
DEFINE LCD_DBIT 4
DEFINE LCD_RSREG PORTB
DEFINE LCD_RSBIT 0
DEFINE LCD_EREG PORTB
DEFINE LCD_EBIT 1
DEFINE LCD_BITS 4 
DEFINE LCD_LINES 2
DEFINE LCD_COMMANDUS 1500
DEFINE LCD_DATAUS 44
DEFINE OSC 4

lcdout "test 2"
PAUSE 500

LABEL VAR WORD
DROEBITI VAR WORD


taki:
if portc.4=0 then
COUNT PORTC.4, 60, LABEL
endif
if label=0 then
goto taki
endif
LCDOUT $FE,$c0, DEC(LABEL), "          "
GOTO TAKI

I have source of signal (chip with name grinded off, but holtek logo is recognizable), which is connected directly to PORTC.4. Also, scope is connected to same pin.

As long as I introduce the statement "if portc.4=0 then"
If it is "=0" then pin is sunk to ground, so no pulses can be detected, and nothing can be seen on scope. If it is "=1", then pin gets driven high, and no pulses can be seen with scope or read too.

Chip is 16F870.

[pedja089]

 TRISA = %11111111       ' Set PORTA to all input
   TRISC = %00000000	    ' Sets all PortB pins to output
   ADCON1 = %10000101      ' Set PORTA analog and right justify result
   ADCON0=%00000000
   low portc.4
   low portc.5

Is there something strange here?

[Art]

Easy! It’s giving you a wider pulse duration at the start to qualify the incoming data.
From there you only need to sample 32 times at the correct interval.
So look for that, then read it in with a 32 step loop.

bitcode var byte[32]
count var byte
pulseduration var byte

pulseduration = time from peak to peak

for count = 0 to 31
bitcode[count] = inputpin
pause pulseduration
next count

Of course, better ways than reading into a 32 byte array, but quickest.

[CuriousOne]

You're omitting an important thing - MCU has own clock, wastes different time on program execution, but incoming data is sent async, so it can't wait for MCU to become ready, so my guess, how it all should work, is as follows:

As pulse arrives, we start recording it as fast as possible, after pulse sequence finished, we just count numbers of 1's and 0's recorded, and based on that, decide what to do with decoded data. Considering total sequence duration and speed, I guess, external sram or eeprom might be needed?

[Art]

That depends. You didn’t display the duration.
If it’s several uS duration pulses, the falling edge of the first longer pulse is the place to mark time,
then waste half a pulse duration before the for-next loop. If you can roughly synchronise from the first pulse (which is what it’s for),
it takes time for the two clocks to drift apart.

If you were to sample bits as fast as you can, you’d still want to do that from the falling edge of the first pulse.

[richard]

for comparison I came up with this , oddly it uses mode code space

'****************************************************************
'*  Name    : deMODULATOR.BAS                                   *
'*  Author  : richard                                           *
'*  Notice  : Copyright (c) 2016                                *
'*          : All Rights Reserved                               *
'*  Date    : 5/29/2016                                         *
'*  Version : 1.0                                               *
'*  Notes   : decodes missing pulse encoded data stream A.5     *
'*          : 16F1825                                           *
'****************************************************************
  #CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF            
#ENDCONFIG
 
OSCCON=$70 
DEFINE OSC 32



'                       PIC 16F1825



    TRISA     = %111110	 ' Make somepins Input 
    trisc     = %111100  ;Make some pins Input   
    ANSELA=0     
    ANSELC=0
    led var latc.0      ;DEBUG
    led2 var latc.1      ;DEBUG
    demod var porta.5     ;demod in
    X VAR byte
    darta   VAR byte[4] 
    counter var word
    dm_state   VAR byte
    lata.0=1             ;DEBUG
    clear
    led=0
    DEFINE DEBUG_REG PORTA
    DEFINE DEBUG_BIT 0       
    DEFINE DEBUG_BAUD 9600
    DEFINE DEBUG_MODE 0     
    pause 2000
    Debug "Start",13 ,10  
    DEFINE PULSIN_MAX 9000

main:
    select case dm_state
        case 0
            PULSIN demod, 0, counter
            if counter > 7800  then
                dm_state=1
                x=0
            endif
        case 1
            pir1.1=0 
            tmr2=0
            t2con=7
            while demod : wend
            if   pir1.1 | (tmr2 < 220)   then
               dm_state=0
            else
                dm_state=2
                tmr2=0
            endif
        case 2
            while !demod : wend
            t2con=0
            if   pir1.1 then 
             dm_state=0
             led=1 
            endif 
            if tmr2 < 150    then 
                darta.0[x]=0
            else
                darta.0[x]=1
            endif
            tmr2=0
            x=x+1
            if x >31 then 
                dm_state=3
            else
                while demod : wend
                t2con=7    
            endif
        case 3
            led2=1     ;DEBUG
        '    Debug 13 ,10 ,hex2 darta[3] ,hex2 darta[2],hex2 darta[1],hex2 darta[0]    ;DEBUG
            Debug 13 ,10 ,bin8 darta[3],bin8 darta[2],bin8 darta[1],bin8 darta[0]    ;DEBUG
            pause 200
            led2=0             ;DEBUG
            dm_state=0
    end select

goto main

[CuriousOne]

the 1ms was just test, I used it to check MCU speed, whenever OSCCON and DEFINE OSC were correct, later it was removed.

I have Henrik's code running, I connect it to actual hardware, and width of large pulse, which should be 9000us, measured only 600 ?

[CuriousOne]

I've copied all code from post #35, including timings.

http://www.picbasic.co.uk/forum/show...165#post138165

[richard]

I have Henrik's code running, I connect it to actual hardware, and width of large pulse, which should be 9000us, measured only 600 ?

then you are doing something wrong ,plus you said in previous posts the pulse was 9900uS it makes a difference . whats correct ?
your looking more scatterlogical than my exwife

[CuriousOne]

haha, no, I'm not blond
Just I'm multi-tasking very hard.

9000, 9900, it was just typo, exact timings are given on the previous page. I don't know what I'm doing wrong, since code is Henrik's. As I said, I verified MCU speed and OSC settings, and they are all correct. Pulse timings are also correct, verified using two different scopes. this is only what I can do.