write code to transfer block of data from 1FFFF104 to 1FFFF164 and blocksize is stores on 1FFFF100.

;please note here that data transfer done in word only

;first word transfer done between the addresses from 1FFFF1(04 - 05 - 06 - 07) to 1FFFF1(64 - 65 - 66 - 67)

;second word transfer done between the addresses from 1FFFF1(08 - 09 - 0A - 0B) to 1FFFF1(68 - 69 - 6A - 6B)

; and so on

; size of block will be available at location 1FFFF100

;Solution:

 TTL transfer
        AREA Myprog, CODE, READONLY
ENTRY
        EXPORT main
main
            LDR R7,=0x1FFFF100      ;first location initialize to the R7
            LDR R6,=0x1FFFF160    ;second location initialize to R6
            LDR R1,[R7,#0x00]        ;data number need to multiply of 4 as PC+4
            LSLS R1,R1,#0x02        
        ;multiply by 4 if words, 2 if half words and instruction not require in bytes are transferring
            LDR R3,=0x04    ; necessary to shift because PC+4   
Labl1    LDR R2,[R7,R3]    ;first word transfer to R2
            STR R2,[R6,R3]    ;first word store from R2
            ADDS R3,R3,#0x04    ;shift due to word transfer
            SUBS R1,R1,#0x04    ;
            BHI Labl1
done
            SWI &11
            END

Result:

Red colors: data fetch from memory

Green colors: data stored to the memory

Data trasfer instructions of ARM cortex M0/M0+ to memory access through registers.

Memory Accesses register

The Cortex-M0 and Cortex-M0+ processors support a number of memory access instructions, which support various data transfer sizes and addressing modes. The supported data transfer sizes are Word, Half Word, and Byte

Table: Memory access instructions for various transfer sizes

Transfer size Unsigned load     Signed load     Signed/Unsigned store
•Word                 LDR                     LDR                     STR
•Half word         LDRH                  LDRSH               STRH
•Byte                  LDRB                   LDRSB               STRB

Write KL25Z ARM cortex M0+ code to transfer data with in the processor (register to register)

 Assembly code

; Write assembly code to trasfer the data with in the processor
;------------------------------------------------------------------
; Targeted instructions are of mainly four type
; 1. Data transfer Register to Rregister
; 2. data transfer Register to Rregister with all flags get affected
; 3. Immediate data into register with flags get affected
; 4. Special register to register and vice versa
;---------------------------------------------------------------------
        TTL transfer
        AREA Myprog, CODE, READONLY

ENTRY
        EXPORT main
main

        LDR R1,=0x25    ; Load R1 with 0x25
        LDR R2,=0x23    ; Load R2 with 0x23
        MOV R7,R1        ; Mov content of R7 to R1
        MOVS R3,R2        ; Mov content of R2 to R3
        MOVS R4,#0x02    ; Mov immediate 8 bit data 0x22 to R4
        MRS R5,MSP        ; Save specical purpose register APSR's content into R5

        ADDS R5,R5,#0x01; Increse main stack pointer value stored in R5 by 1
        MSR MSP, R5        ; Load content of thr R5 into APSR
done
        SWI &11            ; Call system interrupt to end the program
        END

 Result:

 Embedded C code

#include "MKL25Z4.h"

int main(void)
{
volatile char a = 0x06, c=0x00;
volatile short int    d= 0x00;
c= a;
d = c;
return 0 ;
}

Result:

Data transfer instrutions with in the processor of ARM cortex M0+

 Moving Data within the Processor

Write embedded C code for KL25Z to transfer data from memory to variable and variable to memory.

Code 1: data transfer from memory to variable and variable to memory of byte size

 #include "MKL25Z4.h"

int main(void)
{
volatile char a = 0x06, c=0x00, d= 0x00;
volatile char *b = &c;
*b= a;                             // variable to memory 8 bit data transfer
d =*b;                             // memory to variable 8 bit data transfer
return 0 ;
}

Result:

Initial value:

After execution of code

 

Code 2: data transfer of half word from memory to variable and variable to memory.

#include "MKL25Z4.h"

int main(void)
{
volatile short int a = 0x06, c=0x00, d= 0x00;
volatile short int  *b = &c;
*b= a;                                // variable to memory 16 bit data transfer
d =*b;                                // memory to variable 16 bit data transfer
return 0 ;
}

Code 3: data transfer of word from memory to variable and variable to memory.

#include "MKL25Z4.h"

int main(void)
{
volatile int a = 0x06, c=0x00, d= 0x00;
volatile int  *b = &c;
*b= a;                                     // variable to memory 32 bit data transfer                           
d =*b;                                     // memory to variable 32 bit data transfer
return 0 ;
}