Origin of Assembly Table

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

Here is the code:

http://pastebin.com/f3d55f851

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

Code:

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

As Mister_e says...

Hi Matt, Welcome to the PBP forum.

Quote:

Originally Posted by dksoba

<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

Quote:

Originally Posted by Acetronics

Hi, Matt

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

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

Matt

Hi, Matt

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

in assembler NOW ...

Code:

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 ???

Quote:

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