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Compiler/MSP-EXP430G2: I cannot find why my code occupies the RAM heavily

David__
Genius 3585 points
Part Number: MSP-EXP430G2


Tool/software: TI C/C++ Compiler

Hello, E2E.

I'm using CCS 8 on Windows to program UART related features for my MSP430G2 launchpad.

I believe the above code doesn't use any variables. However, the RAM is using 80 bytes.

I thought this might be the optimization level problem. However, if I switch this to the highest level, the RAM is still using 80 bytes.

Also, this simple LED blinking example takes 80 bytes of RAM.

What are this 80 bytes used for and can I decrease this in order to use more global variables?

  • 0
    TI__Mastermind 49692 points

    Hi David,

    Please read through 's Optimizing C Code for Size With MSP430™ MCUs: Tips and Tricks app note. It should help you reduce the RAM usage.

    Regards,

    James

  • 0
    Guru 100845 points
    That 80 bytes is almost certainly the heap. [Build Settings->Linker->Basic Options]. If you're not using malloc you can reduce this.

    I don't know if you can set it to 0, but I've set it to 16 without trouble.
  • 0 in reply to Bruce McKenney
    Genius 3585 points 
     output                                  attributes/
section   page    origin      length       input sections
--------  ----  ----------  ----------   ----------------
.stack     0    000003c0    00000040     UNINITIALIZED
                  000003c0    00000002     rts430_eabi.lib : boot.c.obj (.stack)
                  000003c2    0000003e     --HOLE--

.text      0    0000c000    00000082     
                  0000c000    0000005a     main.obj (.text:main)
                  0000c05a    00000014     rts430_eabi.lib : boot.c.obj (.text:_c_int00_noinit_noargs)
                  0000c06e    00000008                     : isr_trap.asm.obj (.text:_isr:__TI_ISR_TRAP)
                  0000c076    00000006                     : exit.c.obj (.text:abort)
                  0000c07c    00000004                     : pre_init.c.obj (.text:_system_pre_init)
                  0000c080    00000002     main.obj (.text:USCI0RX_ISR)

.cinit     0    0000c000    00000000     UNINITIALIZED

.binit     0    0000c000    00000000     

.init_array 
*          0    0000c000    00000000     UNINITIALIZED

TRAPINT    0    0000ffe0    00000002     
                  0000ffe0    00000002     rts430_eabi.lib : int00.asm.obj (.int00)

PORT1      0    0000ffe4    00000002     
                  0000ffe4    00000002     rts430_eabi.lib : int02.asm.obj (.int02)

PORT2      0    0000ffe6    00000002     
                  0000ffe6    00000002     rts430_eabi.lib : int03.asm.obj (.int03)

ADC10      0    0000ffea    00000002     
                  0000ffea    00000002     rts430_eabi.lib : int05.asm.obj (.int05)

USCIAB0TX 
*          0    0000ffec    00000002     
                  0000ffec    00000002     rts430_eabi.lib : int06.asm.obj (.int06)

USCIAB0RX 
*          0    0000ffee    00000002     
                  0000ffee    00000002     <whole-program> (.int07)

TIMER0_A1 
*          0    0000fff0    00000002     
                  0000fff0    00000002     rts430_eabi.lib : int08.asm.obj (.int08)

TIMER0_A0 
*          0    0000fff2    00000002     
                  0000fff2    00000002     rts430_eabi.lib : int09.asm.obj (.int09)

WDT        0    0000fff4    00000002     
                  0000fff4    00000002     rts430_eabi.lib : int10.asm.obj (.int10)

COMPARATORA 
*          0    0000fff6    00000002     
                  0000fff6    00000002     rts430_eabi.lib : int11.asm.obj (.int11)

TIMER1_A1 
*          0    0000fff8    00000002     
                  0000fff8    00000002     rts430_eabi.lib : int12.asm.obj (.int12)

TIMER1_A0 
*          0    0000fffa    00000002     
                  0000fffa    00000002     rts430_eabi.lib : int13.asm.obj (.int13)

NMI        0    0000fffc    00000002     
                  0000fffc    00000002     rts430_eabi.lib : int14.asm.obj (.int14)

.reset     0    0000fffe    00000002     
                  0000fffe    00000002     rts430_eabi.lib : boot.c.obj (.reset)

$fill000   0    0000ffde    00000002     
                  0000ffde    00000002     --HOLE-- [fill = ffff]

MODULE SUMMARY

       Module                                   code   ro data   rw data
       ------                                   ----   -------   -------
    .\
       main.obj                                 92     0         0      
    +--+----------------------------------------+------+---------+---------+
       Total:                                   92     0         0      
                                                                        
    C:\Users\user\AppData\Local\Temp\
       {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}   0      2         0      
    +--+----------------------------------------+------+---------+---------+
       Total:                                   0      2         0      
                                                                        
    C:\ti\ccsv8\tools\compiler\ti-cgt-msp430_18.1.3.LTS\lib\rts430_eabi.lib
       boot.c.obj                               20     2         0      
       isr_trap.asm.obj                         8      0         0      
       exit.c.obj                               6      0         0      
       pre_init.c.obj                           4      0         0      
       int00.asm.obj                            0      2         0      
       int02.asm.obj                            0      2         0      
       int03.asm.obj                            0      2         0      
       int05.asm.obj                            0      2         0      
       int06.asm.obj                            0      2         0      
       int08.asm.obj                            0      2         0      
       int09.asm.obj                            0      2         0      
       int10.asm.obj                            0      2         0      
       int11.asm.obj                            0      2         0      
       int12.asm.obj                            0      2         0      
       int13.asm.obj                            0      2         0      
       int14.asm.obj                            0      2         0      
    +--+----------------------------------------+------+---------+---------+
       Total:                                   38     26        0      
                                                                        
       Stack:                                   0      0         64     
    +--+----------------------------------------+------+---------+---------+
       Grand Total:                             130    28        64     


GLOBAL SYMBOLS: SORTED ALPHABETICALLY BY Name 

address   name                  
-------   ----                  
0000004a  ADC10AE0              
000001b0  ADC10CTL0             
000001b2  ADC10CTL1             
00000048  ADC10DTC0             
00000049  ADC10DTC1             
000001b4  ADC10MEM              
000001bc  ADC10SA               
00000057  BCSCTL1               
00000058  BCSCTL2               
00000053  BCSCTL3               
0000c076  C$$EXIT               
00000059  CACTL1                
0000005a  CACTL2                
000010fb  CALBC1_12MHZ          
000010f9  CALBC1_16MHZ          
000010ff  CALBC1_1MHZ           
000010fd  CALBC1_8MHZ           
000010fa  CALDCO_12MHZ          
000010f8  CALDCO_16MHZ          
000010fe  CALDCO_1MHZ           
000010fc  CALDCO_8MHZ           
0000005b  CAPD                  
00000056  DCOCTL                
00000128  FCTL1                 
0000012a  FCTL2                 
0000012c  FCTL3                 
00000000  IE1                   
00000001  IE2                   
00000002  IFG1                  
00000003  IFG2                  
00000022  P1DIR                 
00000025  P1IE                  
00000024  P1IES                 
00000023  P1IFG                 
00000020  P1IN                  
00000021  P1OUT                 
00000027  P1REN                 
00000026  P1SEL                 
00000041  P1SEL2                
0000002a  P2DIR                 
0000002d  P2IE                  
0000002c  P2IES                 
0000002b  P2IFG                 
00000028  P2IN                  
00000029  P2OUT                 
0000002f  P2REN                 
0000002e  P2SEL                 
00000042  P2SEL2                
0000001a  P3DIR                 
00000018  P3IN                  
00000019  P3OUT                 
00000010  P3REN                 
0000001b  P3SEL                 
00000043  P3SEL2                
00000172  TA0CCR0               
00000174  TA0CCR1               
00000176  TA0CCR2               
00000162  TA0CCTL0              
00000164  TA0CCTL1              
00000166  TA0CCTL2              
00000160  TA0CTL                
0000012e  TA0IV                 
00000170  TA0R                  
00000192  TA1CCR0               
00000194  TA1CCR1               
00000196  TA1CCR2               
00000182  TA1CCTL0              
00000184  TA1CCTL1              
00000186  TA1CCTL2              
00000180  TA1CTL                
0000011e  TA1IV                 
00000190  TA1R                  
000010db  TLV_ADC10_1_LEN       
000010da  TLV_ADC10_1_TAG       
000010c0  TLV_CHECKSUM          
000010f7  TLV_DCO_30_LEN        
000010f6  TLV_DCO_30_TAG        
0000005d  UCA0ABCTL             
00000062  UCA0BR0               
00000063  UCA0BR1               
00000060  UCA0CTL0              
00000061  UCA0CTL1              
0000005f  UCA0IRRCTL            
0000005e  UCA0IRTCTL            
00000064  UCA0MCTL              
00000066  UCA0RXBUF             
00000065  UCA0STAT              
00000067  UCA0TXBUF             
0000006a  UCB0BR0               
0000006b  UCB0BR1               
00000068  UCB0CTL0              
00000069  UCB0CTL1              
0000006c  UCB0I2CIE             
00000118  UCB0I2COA             
0000011a  UCB0I2CSA             
0000006e  UCB0RXBUF             
0000006d  UCB0STAT              
0000006f  UCB0TXBUF             
0000c080  USCI0RX_ISR           
00000120  WDTCTL                
00000400  __STACK_END           
00000040  __STACK_SIZE          
0000c06e  __TI_ISR_TRAP         
0000ffe0  __TI_int00            
0000ffe4  __TI_int02            
0000ffe6  __TI_int03            
0000ffea  __TI_int05            
0000ffec  __TI_int06            
0000ffee  __TI_int07            
0000fff0  __TI_int08            
0000fff2  __TI_int09            
0000fff4  __TI_int10            
0000fff6  __TI_int11            
0000fff8  __TI_int12            
0000fffa  __TI_int13            
0000fffc  __TI_int14            
ffffffff  __TI_pprof_out_hndl   
ffffffff  __TI_prof_data_size   
ffffffff  __TI_prof_data_start  
ffffffff  __c_args__            
0000c05a  _c_int00_noinit_noargs
0000fffe  _reset_vector         
000003c0  _stack                
0000c07c  _system_pre_init      
0000c076  abort                 
0000c000  main

    Wow, thanks for telling me, Bruce!

    Bruce McKenney47378 said:
    That 80 bytes is almost certainly the heap.

    The stack size was the reason!

    By the way, for this example, it is not possible to eliminate RTS libraries?

  • 0 in reply to David__
    TI__Mastermind 49692 points

    Hello David,

    The RTS libraries are required for C projects. In your .map file, the RTS-related code is only 38 bytes, which is quite small and outside of RAM, which was your initial concern. You can read more about the RTS libraries in the MSP430 Optimizing C/C++ Compiler v18.9.0.STS User's Guide and MSP430 Assembly Language Tools v18.9.0.STS User's Guide.

    CCSv4 beginner -- error with rts430.lib<boot.obj>

    Regards,

    James

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