C51: Accessing Specific Memory Bytes

Information in this knowledgebase article applies to:

• C51 All Versions

QUESTION

How can I access any byte of internal memory without reserving it? At some time, I want to download all memory contents, including all variables and registers. It is no problem working in Assembly, but can I do this from a C program?

ANSWER

Yes. You may use the DBYTE macro in the C51 library. Refer to the ABSACC.H include file. The definition for DBYTE is...

#define DBYTE ((unsigned char volatile data  *) 0)

You may then access any byte in internal memory as shown in the following C code:

for (i = 0; i < 0x80; i++)
  {
  unsigned char my_data;

  my_data = DBYTE[i];  // Read DATA byte
  SBUF = my_data;  // Write DATA byte to serial port

  // Delay for TI here
  }

MORE INFORMATION

• C51: Reserving Code Space
• C51: Reserving Space in Code Memory
• C51: Reserving Space in Code Banks

Last Reviewed: Thursday, February 25, 2021