C51: Code Banking With SiLabs C8051F12x/F13x Devices

Information in this article applies to:

• C51 Version 7

QUESTION

I'm using the Silicon Laboratories (former Cygnal) C80C51F120, C80C51F121, C80C51F122, C80C51F123, C80C51F124, C80C51F125, C80C51F126, C80C51F127, C80C51F130, C80C51F131, C80C51F132, and C80C51F133 devices and I need to configure it for code banking. I am confused by the terms used in the SiLabs datasheet and the Keil documentation. They seem not to match and I have therefore the following questions:

1. What is the common area and the size of the common area?
2. How many code banks should I declare in µVision?
3. What will be size of each code bank?
4. If I declared 4 code banks in µVision2, do I get 32K common area + 4x32K code banks?

ANSWER

The SiLabs Application Note 130: Code Banking with the Keil 8051 Tools describes the configuration of the code banking. The code bank 0 is used as a common bank.

The SiLabs on-chip banking mechanism is identical to the example hardware documented in the LX51 User's Guide, Bank Switching, Examples, Banking with Common Area. No code may be assigned to bank 0 since this hardware decoding is used for the common area.

Below are the answers to your questions:

1. The common area is identical to bank 0 (C:0-C:0x7FFF) and is 32KB.
2. You need to define 4 code banks in L51_BANK.A51 configuration file.
3. The size of each code bank is 32KB.
4. Bank 0 is the common area. No module can be assigned to code bank 0.

The best way is to use the L51_BANK.A51 and STARTUP.A51 files from the Silabs website:

AN130SW.ZIP.

For generating a HEX file, you may use the OHX51 directive MERGE32K.

MORE INFORMATION

• Refer to Code Banking in the LX51 User's Guide.
• Refer to Code Banking in the OHX51 User's Guide.

SEE ALSO

• C51: Creating Code Banking Programs
• BL51: The Code Banking Mechanism
• LX51: Generating Hex Files for Banked Applications
• C51: Const Variable Banking With Silicon Labs C8051F12x Devices

Last Reviewed: Thursday, February 25, 2021