8051 interfacing with external Ram written in C

[taday]

8051 interfacing to external memory

Dear friends!

I'm using at89c52 & I want to know how can I interface it with external memory .

I'm looking for examples written in C language.

thanks in advance!!!

 

[IanP]

external ram 8051

For writing to external RAM location you can always use the following sequence:

#asm
MOV DPTR, xxxxh ; memory address
MOVX @DPTR, A
...
#endasm

and for reading from external RAM the following:

#asm
MOV DPTR, xxxxh
MOVX A, @DPTR
...
#endasm

DPTR is the microcontroler data pointer, and the MOVX istruction operates with external RAM ..

 

[suromenggolo]

external ram interface with 8051

if you use Keil with xdata parameter like

unsigned char xdata b;

main();
{
ACC = b;
}

result compiler is

MOV DPTR, xxxx
MOVX A, @DPTR

 

[dinesh322]

external i/o interfacing of 8051

Can somebody please tell me the circuit of interfacing the external RAM to 89c52 .
Thanks
Dinesh

 

[elchula]

external memory ram circuit, 8051

It's a simple circuit. You can use 74HC373 (or 273....hic, I don't understand clearly) to latch DATA from 89C52 to write or read data to/from IC RAM - 6264....

 

[SISWANTO]

how to know ram memory in c language

Hi dinesh322,
please take a look the attachment, it is a minimum system of AT89C51 and I using that board togather with EPROM Emulator. Hope this can help you.



Sis

 

[bsiswoyo]

external ram of 8051 using c

Dear friends!

I'm using at89c52 & I want to know how can I interface it with external memory .

I'm looking for examples written in C language.

thanks in advance!!!

if you need to write/read external memory without asm pragma please test this sample:

/* test i/o 8255 mapping to 8000H - 8003H */
char xdata PA _at_ 0x8000;
char xdata PB _at_ 0x8001;
char xdata PC _at_ 0x8002;
char xdata CR _at_ 0x8003;

/* dummy data port at external ram from 0000h */
char xdata PA_dummy;
char xdata PB_dummy;
char xdata PC_dummy;

void initPPI()
{ /* set all port for output */
CR = 0x80;
}

void main()
{
/* read port a */
PA_dummy = PA;

/* read port b */
PB_dummy = PB;

/* read port c */
PC_dummy = PC
}

thx