Origin of Assembly Table

[dksoba]

I am working on a PID controller that also does the quadrature decoding of an optical encoder (which I made tehehe). I have it basically working using assembly interrupts.

The basic operation is to get the current encoder channels and the encoder channels from the last interrupt (interrupt on change of pin value) into one byte, which goes from 0-15 (I make sure to clear the 4 MSB bits).Then it uses a lookup table (In assembly, consisting of a PCL addition to a GOTO branch) to determine what this code means. I know it'd be faster to shift my index left by 1 or 2 places, and then have the necessary instructions on 2 or 4 lines. However, I'm not there yet.

My main concern is that right now, I put my interrupt service routine as close the top of the code as possible, w/the table near the top of the interrupt service routine. I do this because I want the PCL to have a value that is less than 255-15, so that when I add to it jumps to the right place. According to AN556 from Microchip (http://www.engr.usask.ca/classes/EE/331/AN556.pdf) standard practice is to put an "org [address]" at the beginning of a table. What I can't figure out, even after searching quite a bit, is what is a good value for this? I've played around with it a bit, but it either doesn't compile because the address interferes w/PBP code, or crashes my code.

Where can I determine a good value for the ORG of my table? Also, I know that the interrupt service routine needs to be near the top, is this because it has to be on the first page?

I'm a bit confused about these pages and stuff. What's the best way to attach code?

Please advise.

Thanks,
Matt

[dksoba]

Here is the code:

http://pastebin.com/f3d55f851

[Acetronics2]

Hi, Matt

You have two solutions ...Using PBP ...


1) Use a Lookup table ... PBP will care of all the adresses.

2) Using an assembler retrieve table

	
peekcode ( 850 + sampled ), delay		' 881 = 850 + 31 !!!

.
.

END

'*****************************************************************************
'Fading_Table
'*****************************************************************************
'         			 0   1   2   3   4   5   6   7   8   9  
'
Pokecode @881,		             24, 27, 29, 32, 35, 38, 41, 44, 47,_	'  30
         			 50, 54, 57, 60, 64, 68, 71, 75, 79, 83,_	'  40
         			 87, 91, 96,100,104,109,113,118,123,127,_	'  50
         			132,137,142,147,153,158,163,169,174,180,_	'  60
         			186,191,197,203,209,212,217,245,250,  1,_	'  70
         			  7, 13, 21, 30, 39, 48, 57, 24, 25, 26,_	'  80
         			 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,_	'  90
         			 37, 38, 39, 40, 41, 43, 44, 45, 46, 48,_	' 100
         			 49, 50, 52, 53, 54, 56, 57, 59, 60, 62,_	' 110
         			 63, 65, 67, 68, 70, 72, 73, 75, 77, 79,_	' 120
         			 81, 83, 84, 86, 88, 90, 92, 94, 97, 99,_	' 130
         			101,103,105,107,110,112,114,117,119,122,_	' 140
         			124,126,129,132,134,137,139,142,145,148,_	' 150
         			150,153,156,159,162,165,168,172,176,180	        ' 160
		     	     
 END

Note, for me , the " sampled " value was from 31 to ... a lot !!!

Here , the best is to compile @ first using the Highest adresses of the Prog memory, to see where the program ends, and then shift the table adress to lower adresses.

Here, I have 140 values, so, first compile has been made with Pokecode @ 860 ( leaving little room for the END statement ! - was a 12F675 )

The MPLAB Program window, here is a GREAT help ...


some months after that ... I've added as much program lines as possible ... this explains my table is @ the very top memory adresses available. ( 1022/1024 lines occupied ...)

Alain

[Pic_User]

Hi Matt, Welcome to the PBP forum.

<snip>...
I'm a bit confused about these pages and stuff. What's the best way to attach code?
Please advise.

Thanks,
Matt

http://www.picbasic.co.uk/forum/misc.php?do=bbcode

As Mister_e says:
[ code] paste your code here [/code ] leave out the spaces inside the [/code ] tags

[dksoba]

Hi, Matt

You have two solutions ...Using PBP ...

My interrupt is an assembly interrupt, so I can't have PBP code there... right?

Matt

[Acetronics2]

Hi, Matt

Its no problem ... the method is the same ...

in assembler NOW ...

  Line    Address    Opcode        Label                  Disassembly           

    805     324       3052   Z000A7            MOVLW 0x52                       
    806     325       0744                     ADDWF _Sampled, W                
    807     326       00B8                     MOVWF 0x38                       
    808     327       3003                     MOVLW 0x3                        
    809     328       1803                     BTFSC STATUS, 0                  
    810     329       3E01                     ADDLW 0x1                        
    811     32A       00B9                     MOVWF 0x39                       
    812     32B       0838                     MOVF 0x38, W                     
    813     32C       00B0                     MOVWF R8                         
    814     32D       0839                     MOVF 0x39, W                     
    815     32E       00B1                     MOVWF 0x31                       
    816     32F       20B6                     CALL JUMPMAN                     
    817     330       00BD                     MOVWF delay                      
   .
   .
   .
   .
           
    879     36E       3FFF                                                      
    880     36F       3FFF                                                      
    881     370       3FFF                                                      
    882     371       3418                     RETLW 0x18          ; jumpman label here ..             
    883     372       341B                     RETLW 0x1b                       
    884     373       341D                     RETLW 0x1d                       
    885     374       3420                     RETLW 0x20                       
    886     375       3423                     RETLW 0x23                       
    887     376       3426                     RETLW 0x26                       
    888     377       3429                     RETLW 0x29                       
    889     378       342C                     RETLW 0x2c                       
    
...
         
    991     3DE       3465                     RETLW 0x65                       
    992     3DF       3467                     RETLW 0x67                       
    993     3E0       3469                     RETLW 0x69                       
    994     3E1       346B                     RETLW 0x6b                       
    995     3E2       346E                     RETLW 0x6e                       
    996     3E3       3470                     RETLW 0x70                       
    997     3E4       3472                     RETLW 0x72                       
    998     3E5       3475                     RETLW 0x75                       
    999     3E6       3477                     RETLW 0x77                       
   1000     3E7       347A                     RETLW 0x7a                       
   1001     3E8       347C                     RETLW 0x7c                       
   1002     3E9       347E                     RETLW 0x7e                       
   1003     3EA       3481                     RETLW 0x81                       
   1004     3EB       3484                     RETLW 0x84                       
   1005     3EC       3486                     RETLW 0x86                       
   1006     3ED       3489                     RETLW 0x89                       
   1007     3EE       348B                     RETLW 0x8b                       
   1008     3EF       348E                     RETLW 0x8e                       
   1009     3F0       3491                     RETLW 0x91                       
   1010     3F1       3494                     RETLW 0x94                       
   1011     3F2       3496                     RETLW 0x96                       
   1012     3F3       3499                     RETLW 0x99                       
   1013     3F4       349C                     RETLW 0x9c                       
   1014     3F5       349F                     RETLW 0x9f                       
   1015     3F6       34A2                     RETLW 0xa2                       
   1016     3F7       34A5                     RETLW 0xa5                       
   1017     3F8       34A8                     RETLW 0xa8                       
   1018     3F9       34AC                     RETLW 0xac                       
   1019     3FA       34B0                     RETLW 0xb0                       
   1020     3FB       34B4                     RETLW 0xb4                       
   1021     3FC       0063   Z000C3            SLEEP                            
   1022     3FD       2BFC                     GOTO Z000C3                      
   1023     3FE       3FFF                                                      
   1024     3FF       3FFF

does it sound good now ???

Note it's the straight Compiled PBP lines ... soooo , speed is " not so bad " don't you think ???

so I can't have PBP code there... right?

It's a very very good question, indeed ...

But, If I tell you more ... Darrel will " blow a couple of fuses " ... LOL !

Alain