Memory use - how much do you use?

[mackrackit]

I played with this some last night, did some reading and could not find a solution.
Maybe Darrel or Bruce will chime in...

[Darrel Taylor]

I played with this some last night, did some reading and could not find a solution.
Maybe Darrel or Bruce will chime in...

DING!

PBP's system vars use a minimum of 24 bytes.
Complex formulas can increase that, but it appears you don't have any of those yet.

So you create 40 additional byte variables and it's full. (24 + 40 = 64)

As for "LST View" ...

It apparently just looks for the last occurrence of "RAM_START +" and uses that address to calculate how much RAM was used.

That address is already referenced to RAM_START, but in the program, this line subtracts the start address again, which leaves the count too low.

ramU = ramF - ramS

Add 20h (32) to the 31 bytes reported and you get 63, the last address in RAM.

I think that line should be ...

    ramU = ramF + 1

However, RAM assignments are not always contiguous. You could have a single variable in BANK3 (chip other than 675) and it'll show almost all the RAM has been used, when there's only a few bytes being used. Or the last address may be the beginning of an array, which it won't count either.

It's a difficult task to count RAM bytes used.
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[mackrackit]

Thanks Darrel.

I saw where LST View was giving some "funny" results last night also. Now I know why. Time to do a "bug" fix. If possible...

[Darrel Taylor]

Dave,

Just a little more info for updating LST View.
It calculates the Total RAM by taking (RAM_END - RAM_START + 1)
As an example this is from a 16F877 ...

  00000020            00012 RAM_START                       EQU     00020h
  000001EF            00013 RAM_END                         EQU     001EFh
  00000004            00014 RAM_BANKS                       EQU     00004h
  00000020            00015 BANK0_START                     EQU     00020h
  0000007F            00016 BANK0_END                       EQU     0007Fh
  000000A0            00017 BANK1_START                     EQU     000A0h
  000000EF            00018 BANK1_END                       EQU     000EFh
  00000110            00019 BANK2_START                     EQU     00110h
  0000016F            00020 BANK2_END                       EQU     0016Fh
  00000190            00021 BANK3_START                     EQU     00190h
  000001EF            00022 BANK3_END                       EQU     001EFh

(RAM_END - RAM_START + 1) = 1EFh - 20h + 1 = 464 bytes
But the 16F877 only has 368 bytes.

The extra count is from the SFR's that are at the top of each bank.

GP RAM in each bank doesn't start at the same place on every 16F, so I think you'll need to find the amount in each bank and add them together to get the total RAM.

(BANK0_END - BANK0_START + 1) + (BANK1_END - BANK1_START + 1) + (BANK2_END - BANK2_START + 1) + (BANK3_END - BANK3_START + 1)
(  0007Fh  -   00020h    + 1) + (  000EFh  -   000A0h    + 1) + (  0016Fh  -   00110h    + 1) + (  001EFh  -   00190h    + 1)
(            60h            ) + (            50h            ) + (            60h            ) + (            60h            )
= 170h = 368

Then it's the same for the Used RAM. You need to subtract the SFR space from the variables address, or somehow reference it to the BANKx_START of the bank that it's in to find out how much has been used.

hth,