Ernie,
Yes I do have an excel spreadsheet with the values calculated. And I could possibly linearize the curve but loose accuracy. But about this RETLW command, how does it work and where can I find the syntax etc etc for it?
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Ernie,
Yes I do have an excel spreadsheet with the values calculated. And I could possibly linearize the curve but loose accuracy. But about this RETLW command, how does it work and where can I find the syntax etc etc for it?
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Darrel,
I don't think I can use that approach since the ADCIN command only lets you store the result in a VAR not a CON. How would I tell it what values from 0-1023 to pull out from memory?
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The reading from the POT should be put in a variable.
The CON is the address of the Data Table that gets stored in program memory.
Then the A/D reading would be used as an offset into the data table in order to find the correct value.
<br>
DT
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Thanks Darrel,
I works GREAT! I just hope now there isn't a limit to the number of values I can put in the Datatable. If there is, then i'm praying that its 1024!!!!!
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Nope,
You are only limited by the amount of available memory in Program Space.
Cheers,
DT
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Well I got a 125KB, I think I should be fine!
Thanks,
Nikhil
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The chip might have 128k, but keep in mind that PicBasic Pro can only address the first 64K of it directly.
Since the table will only use 2K, you should be fine for now.
If the program gets "A LOT" bigger, it's possible to place the table in the upper 64k area, but the readcode would need to be changed to ASM.
But you can worry about that later.
<br>
DT
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Ahhh... the LOOKUP and LOOKUP2 statements impliment the RETLW method for you. Lots cleaner.
Several problems: LOOKUP2 will return words, but has a limit of 85 values (and wastes 50% more room then LOOKUP). LOOKUP1 will fit 255 values, but they are only a byte each (but 1 byte takes 1 program location).
255 is usefull, but 256 would be lots nicer. Using 255 locations just need a work-around for the 256th value, simple in a SELECT-CASE form.
SO... not the worst, each value gets looked up for it's exact value. You would expect 1024 word lookups to fit in 2K of program memory.
Ready for it?
BUT !!!
The LOOKUP statement needs to start on a even 256 address boundary (don't ask why, it's an assembler issue). To do this, PBP seems to just waste code space till it gets to the next boundary.
I tried a sample program compiled for a PIC16F88, which has a 4K word codespace. The program did not fit. I looked at the disassembly I saw the problem was with this wasted codespace.
Since you have 125K it will fit, and hopefully you can accept the wasted space (basically, you'll need 2:1 to fit the lookups).
Sample code:
If you do run out of codespace, let me know and I'll help with some asm code for this.Code:D2A_Result var word ' raw data from D2A conversion D2A_Conversion var word ' converted result ' read the D2A, place Result in D2A_result select case D2A_result case is <256 lookup D2A_result.byte0, _ [$00, $00, $00, $00, $00, $00, $00, $00, _ ' 0-7 lo bytes $00, $00, $00, $00, $00, $00, $00, $00, _ ' 8-15 lo bytes $00, $00, $00, $00, $00, $00, $00, $00, _ ' 16 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 24 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 32 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 40 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 48 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 56 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 64 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 72 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 80 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 88 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 96 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 104 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 112 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 120 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 128 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 136 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 144 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 152 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 160 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 168 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 176 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 184 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 192 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 200 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 208 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 216 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 224 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 232 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 240 $00, $00, $00, $00, $00, $00, $00], _ ' 248 - 255 D2A_Conversion.byte0 lookup D2A_result.byte0, _ [$00, $00, $00, $00, $00, $00, $00, $00, _ ' 0-7 hi bytes $00, $00, $00, $00, $00, $00, $00, $00, _ ' 8 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 16 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 24 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 32 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 40 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 48 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 56 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 64 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 72 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 80 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 88 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 96 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 104 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 112 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 120 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 128 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 136 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 144 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 152 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 160 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 168 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 176 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 184 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 192 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 200 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 208 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 216 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 224 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 232 $00, $00, $00, $00, $00, $00, $00, $00, _ ' 240 $00, $00, $00, $00, $00, $00, $00], _ ' 248 - 255 D2A_Conversion.byte1 case 256 D2A_Conversion.byte0 = $00 D2A_Conversion.byte1 = $00 case is < 512 ' same as before, 2 LOOKUP tables case 512 D2A_Conversion.byte0 = $00 D2A_Conversion.byte1 = $00 case is < 768 ' same as before, 2 LOOKUP tables case 768 D2A_Conversion.byte0 = $00 D2A_Conversion.byte1 = $00 case else ' this case handles 769 to 1023 ' same as before, 2 LOOKUP tables end select
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