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Ringo42
Joined: 07 May 2004
Posts: 263
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| Not enough Ram in 18F2455 |
 Posted: Sun Feb 03, 2008 3:46 pm |
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I'm using a 18F2455 with a bunch of arrays declared like this:
int8 message40[39]={A,l,space,back,l,space,y,o,u,r,space,b,a,s,e,s,space,a,r,e,space,b,e,l,o,n,g,space,t,o,space,u,s,space,ENTER,execute};
This is the 40th one I declared. With the first 39 the compiler says I have used 24% of Ram. The first 39 are of similar size. When I add the 40th I get "not enough Ram error".
Why would 39 take 24% and the next put me over the limit? It is an 18 series part so I should not need the *16 for pointers correct? All my declarations are in a function, I tried moving the 40th to the top of the code to make it Global but that did not help.
Any ideas?
Thanks
Ringo
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Ringo Davis |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Feb 03, 2008 3:58 pm |
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1. What is your compiler version ?
| Quote: | | int8 message40[39]={A,l,space,back,l,space,y,o,u,r,space |
2. Are the arrays really declared like that ?
Individual ASCII characters are normally declared in single quotes.
As shown above, they are not characters, they're symbols. You would
need a #define statement for each symbol. |
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Ringo42
Joined: 07 May 2004
Posts: 263
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| Posted: Sun Feb 03, 2008 4:01 pm |
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They are all in #defines already.
Everything works perfectly up until #40. All the others are very similar. What I'm sending is the Keycodes, so A is actually a 4, and Space is a 40, etc.
They all work up until I hit the memory problem.
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Ringo Davis |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Feb 03, 2008 4:17 pm |
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| But what is the compiler version ? |
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Ringo42
Joined: 07 May 2004
Posts: 263
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| Posted: Sun Feb 03, 2008 4:49 pm |
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4.007
_________________
Ringo Davis |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Feb 03, 2008 5:23 pm |
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I made the test program shown below and compiled it with vs. 4.007.
Each array takes 39 bytes. That's 38 bytes of text and 1 byte for the
string terminator (0x00). The total ram usage is:
| Quote: | | 39 bytes x 40 arrays = 1560 bytes. |
The percentage usage is:
| Quote: | | (1560 bytes / 2048 total RAM) * 100 = 76 % |
There are 6 bytes more, as reported in the .LST file, which undoubtedly
are assigned to scratch variables. But 76% is correct.
| Code: |
CCS PCH C Compiler, Version 4.007, xxxxx 03-Feb-08 15:12
Filename: PCH_Test.lst
ROM used: 6152 bytes (25%)
Largest free fragment is 18424
RAM used: 1566 (76%) at main() level
1566 (76%) worst case
Stack: 0 locations
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| Code: |
#include <18F2455.h>
#fuses XT,NOWDT,PUT,BROWNOUT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
int8 message01[39] = {"High-Current Sink/Source: 25 mA/25 mA "};
int8 message02[39] = {"Four Timer modules (Timer0 to Timer3) "};
int8 message03[39] = {"Up to 2 Capture/Compare/PWM (CCP) modu"};
int8 message04[39] = {"Capture is 16-bit, max. resolution 5.2"};
int8 message05[39] = {"Compare is 16-bit, max. resolution 83."};
int8 message06[39] = {"PWM output: PWM resolution is 1 to 10-"};
int8 message07[39] = {"Enhanced Capture/Compare/PWM (ECCP) mo"};
int8 message08[39] = {"Master Synchronous Serial Port (MSSP) "};
int8 message09[39] = {"supporting 3-wire SPI (all 4 modes) an"};
int8 message10[39] = {"10-bit, up to 13-channel Analog-to-Dig"};
int8 message11[39] = {"module (A/D) with Programmable Acquisi"};
int8 message12[39] = {"Dual Analog Comparators with Input Mul"};
int8 message13[39] = {"C Compiler Optimized Architecture with"};
int8 message14[39] = {"100,000 Erase/Write Cycle Enhanced Fla"};
int8 message15[39] = {"Self-Programmable under Software Contr"};
int8 message16[39] = {"8 x 8 Single-Cycle Hardware Multiplier"};
int8 message17[39] = {"In-Circuit Debug (ICD) via two pins "};
int8 message18[39] = {"Optional dedicated ICD/ICSP port (44-p"};
int8 message19[39] = {"Wide Operating Voltage Range (2.0V to "};
int8 message20[39] = {"Flash/Data EEPROM Retention: > 40 year"};
int8 message21[39] = {"Supports Control, Interrupt, Isochrono"};
int8 message22[39] = {"Supports up to 32 Endpoints (16 bidire"};
int8 message23[39] = {"On-Chip USB Transceiver with On-Chip V"};
int8 message24[39] = {"Streaming Parallel Port (SPP) for USB "};
int8 message25[39] = {"Four Crystal modes, including High Pre"};
int8 message26[39] = {"Two External Clock modes, up to 48 MHz"};
int8 message27[39] = {"8 user-selectable frequencies, from 31"};
int8 message28[39] = {"User-tunable to compensate for frequen"};
int8 message29[39] = {"Secondary Oscillator using Timer1 @ 32"};
int8 message30[39] = {"Dual Oscillator options allow microcon"};
int8 message31[39] = {"USB module to run at different clock s"};
int8 message32[39] = {"Allows for safe shutdown if any clock "};
int8 message33[39] = {"Information contained in this publicat"};
int8 message34[39] = {"applications and the like is provided "};
int8 message35[39] = {"and may be superseded by updates. It i"};
int8 message36[39] = {"ensure that your application meets wit"};
int8 message37[39] = {"Microchip products meet the specificat"};
int8 message38[39] = {"Microchip believes that its family of "};
int8 message39[39] = {"intended manner and under normal condi"};
int8 message40[39] = {"Note the following details of the code"};
//====================================
void main()
{
while(1);
} |
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