C51: Missing Multiple DPTR support for some ATMEL Devices

Information in this knowledgebase article applies to:

• C51 Version 9.50a and earlier

SYMPTOM

The µVision dialog Options for Target - Target did not show the option Use multiple DPTR registers for these ATMEL devices:
AT89S4D12, AT87F51RC, AT89C51RC, AT89S51, AT89LS51, AT89S52, AT89LS52, AT89C55WD, AT87F55WD

CAUSE

The µVision device database contained the wrong options for these devices.

RESOLUTION

You can specify the options for dual data pointer support manually in the dialog Options for Target - C51 - Misc Controls. Please use the right directive for your device. Atmel devices have two different methods to switch the DPTR.

MODA2 for:

• AT89S4D12

MODP2 for:

• AT87F51RC
• AT89C51RC
• AT89S51
• AT89LS51
• AT89S52
• AT89LS52
• AT89C55WD
• AT87F55WD

STATUS

This will be fixed in all C51 versions later than 9.50a. If a project was created with C51 version 9.50a or before, re-select the device in the Options for Target - Device dialog to apply the new options to your project.

MORE INFORMATION

• Refer to MODP2 in the Cx51 User's Guide.
• Refer to MODA2 in the Cx51 User's Guide.

SEE ALSO

• C51: Code Generator Support for Multiple Data Pointers

Last Reviewed: Thursday, February 25, 2021