Motorola MCF5281, MCF5282 user manual Program, Erase, and Verify Sequences

Models: MCF5282 MCF5281

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CFM Operation

WARNING

For proper program and erase operations, it is critical to set fCLK between 150 kHz and 200 kHz. Array damage due to overstress can occur when fCLK is less than 150 kHz. Incomplete programming and erasure can occur when fCLK is greater than 200 kHz.

NOTE

Command execution time increases proportionally with the period of fCLK.

When CFMCLKD is written, the DIVLD bit is set automatically. If DIVLD is 0, CFMCLKD has not been written since the last reset. Program and erase commands will not execute if this register has not been written (see Section 6.4.3.4, “Flash User Mode Illegal Operations”).

6.4.3.2Program, Erase, and Verify Sequences

A command state machine is used to supervise the write sequencing of program, erase, and verify commands. To prepare for a command, the CFMUSTAT[CBEIF] flag should be tested to ensure that the address, data, and command buffers are empty. If CBEIF is set, the command write sequence can be started.

This three-step command write sequence must be strictly followed. No intermediate writes to the CFM module are permitted between these three steps. The command write sequence is:

1.Write the 32-bit longword to be programmed to its location in the CFM array. The address and data will be stored in internal buffers. All address bits are valid for program commands. The value of the data written for verify and erase commands is ignored. For mass erase or verify, the address can be any location in the CFM array. For page erase, address bits [9:0] are ignored.

NOTE

The page erase command operates simultaneously on adjacent erase pages in two interleaved Flash physical blocks. Thus, a single erase page is effectively 2 Kbyte.

2.Write the program, erase, or verify command to CFMCMD, the command buffer. See Section 6.4.3.3, “Flash Valid Commands.”

3.Launch the command by writing a 1 to the CBEIF flag. This clears CBEIF. When command execution is complete, the Flash state machine sets the CCIF flag. The CBEIF flag is also set again, indicating that the address, data, and command buffers are ready for a new command sequence to begin.

MOTOROLA

Chapter 6. ColdFire Flash Module (CFM)

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Page 161
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Motorola MCF5281, MCF5282 user manual Program, Erase, and Verify Sequences