C51: Configuring Dallas 390 and 400 for Contiguous Mode

Information in this article applies to:

• C51 Version 6.12

QUESTION

How do I configure the Keil C51 Tools for the Dallas 390 running in contiguous mode?

BACKGROUND

The Dallas Semiconductor 390 is compatible with the standard 8051, so it is supported by the Keil tools.

The 390 adds extra code and Xdata space. You may use the code banking features of the Keil Cx51 tools to access the extra code space.

ANSWER

To support the Dallas 390, Dallas 400, or Dallas 5240 CPU in Contiguous Mode, you must have the Keil PK51 Professional Developer's Kit Version 6.12 or later.

Configuring the Tools

1. Create a new Project with Project - New Project and select the Dallas DS80C390 (or DS5240) CPU from the µVision2 Device Database.
2. In the Project - Select Device for Target - CPU dialog box, enable both of the following options:
   • Use LX51 instead of BL51
   • Use AX51 instead of A51
3. Select Project - Options for Target - Target - Code ROM Size: Contiguous Mode: 512K program or 16MB program. This option configures all tools, including the debugger/simulator for the Dallas contiguous mode. Note that the correct startup code is required. Specifically, you must set the ACON SFR in the Dallas CPU to contiguous mode.

Additional Memory Spaces

In addition to the memory classes of the classic 8051 CPU, the extended 8051 toolchain adds three additional memory classes. These memory classes are described in detail the Assembler/Utilities User's Guide (A51.PDF), Chapter 2 Architecture Overview, Extended 8051 Variants.

Class   C51 Memory Type   Addresses
-------------------------------------------------------------------------------------
HCONST  const far         Complete CODE space C:0 - C:0xFFFFFF for constant variables

HDATA   far               Complete XDATA space X:0 - C:0xFFFFFF for variables

ECODE   C program code    Complete CODE space for program code

MORE INFORMATION

• C51: Function Pointers in Contiguous Mode
• C51: Absolute Memory Accesses to Maxim 390 Far Memory
• Dallas Semiconductor DS80C390 in the device database.
• More information about the Dallas 390 support may be found in the README.TXT file found in the \KEIL\C51\EXAMPLES\DALLAS 390 directory of your installation.

SEE ALSO

• C51: Maxim 390 Math Accelerator Operations
• C51: Memory Types for Maxim 390 Contiguous Mode
• MON390: CANNOT CONNECT TO DALLAS DS80C400 ON THE DS-TINI-1 B
• µVision DEBUGGER: Debugging With Maxim/Dallas DS5250 Monitor

Last Reviewed: Thursday, February 25, 2021