RC5 decode on a 10F + Question

[ultiblade]

Hi all,

I needed to build a philips RC5 IR decoder, in order to be able to control some other circuitry. When a predefined key is received an decoded the corresponding IO is made high.

However, the example source code's if found could not fit a 10F202.

I used a TSOP(TK)1836 connected to GPIO.0, and in order to "see" the values received the pic sends it's data trough a max232 to my pc. This is only for debug purposes, and must be removed later (removing the moddefs include and serout will free up lots ofprogram memory).

'==== Set fuses ================================================================
@ device pic10F202,wdt_off,mclr_off,protect_off

'==== Set includes =============================================================
INCLUDE "modedefs.bas"                          ' Include for Serout

'==== Set XTAL =================================================================
DEFINE OSC 4                                    ' int XTAL @ 4 Mhz

'==== Set variables ============================================================
Y VAR word                                      ' To Hold the 12-bit RC5 code


'==== Set IO ===================================================================    
IR_PIN VAR GPIO.0                               ' GPIO.0 input pin reading IR data
SERIAL var GPIO.1                               ' GPIO.1 SEROUT 9600-8-n-1 output
TRISIO = %00001001                              ' Set TRIS register input's & output's
OPTION_REG.7 = 0                                ' Internal pull-ups = on

'==== Signal information =======================================================
'Given the information found on http://www.sbprojects.com/knowledge/ir/rc5.htm
'The incoming RC5 signal will look like this :
'
'bit      1    2    3    4    5    6    7    8    9   10   11   12   13   14
'      |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
'uSec   1778 1778 1778 1778 1778 1778 1778 1778 1778 1778 1778 1778 1778 1778

'==== Main program =============================================================  
MAIN:
IF IR_PIN = 1 THEN GOTO MAIN                    ' Wait for the first bit to arive
y.13 = IR_PIN                                    ' Incoming signal 
pauseus 889                                     ' In order to se this 0 we are in the second 
                                                ' period of the first 1.778 msec, so we will 
                                                ' wait another 889 usec to enter the 2nd period.

pauseus 1600                                    ' Almost at the end of the second period, look for
y.12 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.11 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.10 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.9 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.8 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.7 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.6 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.5 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.4 = IR_pin                                    ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.3 = IR_pin                                   ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.2 = IR_pin                                   ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.1 = IR_pin                                   ' a high or low signal
pauseus 178                                     ' Time to the end of this period

pauseus 1600                                    ' Almost at the end of this period, look for
y.0 = IR_pin                                   ' a high or low signal
pauseus 178                                     ' Time to the end of this period

y = ~y                                          ' Invert y word
if Y.lowbyte = 255 then goto ERROR              ' If all lowbytes are 0xFF then noise is received 

'==== DEBUG , output received data serial ======================================
Serout serial,T9600,["STX= ",#y.13,#Y.12,#Y.11,10,13]
Serout serial,T9600,["SYS= ",#y.10,#y.9,#y.8,#y.7,#y.6,13,10]                
Serout serial,T9600,["CMD= ",#Y.5,#y.4,#y.3,#y.2,#y.1,#Y.0,13,10]

'==== End of main loop reset and look again ==================================== 
ERROR:                                        
Y=0                                         ' Clear key codes
PAUSE 250                                   ' debounce
GOTO MAIN                                   ' Return to main loop

My problem now is:
The variable Y is a WORD the has bit's 0 to 13 stored with info.
How do i break up the word in to 3 sections ?

bits 0 to 2 '000' are for the S1, S2 and toggle bit
bits 3 to 7 '00000' are for the System address
bits 8 to 13 '000000' are for the command bits

I want to end up with 2 variables SYSTEM(5 bits) and COMMAND(6 bits)

Anyone ?
(Also, comments on my code are very welcome !!!)

Thanks !