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8. BIOS Support for Program Cloning

The BIOS supports copying designated portions of flash memory from one controller (the master) to another (the clone). The Rabbit Cloning Board connects to the programming port of the master and to the programming port of the clone. This simple circuit can easily be incorporated into test fixtures for fast production.

Figure 8-1 Cloning Board

8.1 Overview of Cloning

If the cloning board is connected to the master, the signal CLKA is held low. This is detected in the BIOS after the reset ends, invoking the cloning support of the BIOS. If cloning has been enabled in the master's BIOS, it will cold boot the target system by resetting it and downloading a primary boot program. The master then sends the entire user program along with other user selected portions of flash memory to the clone, where the boot program receives it and stores it in RAM then copies it to flash. Optionally, the cloned program can begin running on the slave.

For more details on cloning, see Technical Note 207 "Rabbit Cloning Board," available at: rabbit.com.

8.2 Creating a Clone

Before cloning can occur, the master controller must be readied. Once this is done, any number of clones may be created from the same master.

8.2.1 Steps to Enable and Set Up Cloning

The step-by-step instructions to enable and set up cloning on the master are in Technical Note 207. In brief, the steps break down to: attaching the programming cable, running Dynamic C, making any desired changes to the cloning macros, and then compiling the BIOS and user program to the master.

The only cloning macro that must be changed is ENABLE_CLONING, since the default condition is that cloning is disabled.

8.2.2 Steps to Perform Cloning

Once cloning is enabled and set up on the master controller, detach the programming cable and attach the cloning board to the master and the clone. Make sure the master end of the cloning board is connected to the master controller (the cloning board is not reversible) and that pin 1 lines up correctly on both ends. Once this is done, reset the master by pressing Reset on the cloning board. The cloning process will begin.

8.2.3 LED Patterns

While cloning is in progress the LED on the Cloning board will toggle on and off every 1-1.5 seconds. When cloning completes, the LED stays on. If any error occurs, the LED will start blinking quickly. Older versions of cloning used different LED patterns, but the Rabbit 4000 is only supported by versions that use the pattern described here.

8.3 Cloning Questions

The following subsections answer questions about different aspects of cloning.

8.3.1 MAC Address

Some Ethernet-enabled boards do not have the EEPROM with the MAC address. These boards can still be used as a clone because the MAC address is in the system ID block and this structure is shipped on the board and is not overwritten by cloning unless CL_INCLUDE_ID_BLOCKS is set to one.

If you have a custom-designed board that does not have the EEPROM or the system ID block, you may download a program at:

     
 
http://www.rabbit.com/support/feature_downloads.html 
  

to write the system ID block (which contains the MAC address) to your board.

To purchase a MAC address go to:

     
 
http://standards.ieee.org/regauth/oui/index.shtml
  

8.3.2 Different Flash Types

Since the BIOS supports a variety of flash types, the flash EPROM on the two controllers do not have to be identical. Cloning works between master and clone controllers that have different-type flash chips because the master copies its own universal flash driver to the clone. The flash driver determines the particulars of the flash chip that it is driving.

8.3.3 Different Memory Sizes

It is recommended that the cloning master and slave both have the same RAM and flash sizes.

8.3.4 Design Restrictions

Digital I/O line PB1 should not be used in the design if cloning is to be used.