4.4.2 Erasing Executive Memory

The procedure for erasing each page of executive memory is similar to that of erasing program memory and is shown in Figure 2-6. It consists of setting NVMCON to 0x4003 and then executing the programming cycle.

Table 4-15 shows the ICSP programming process for erasing the executive code memory.

Note: The Programming Executive memory must always be erased before it is programmed, as described in Figure 4-5.

Table 4-15. Serial Instruction Execution for Erasing All Pages of Executive Code Memory
Command (Binary)	Data (Hex)	Description
Step 1: Exit the Reset vector.
`0000` `0000` `0000` `0000` `0000` `0000` `0000`	`000000` `000000` `000000` `040200` `000000` `000000` `000000`	`NOP` `NOP` `NOP` `GOTO 0x200` `NOP` `NOP` `NOP`
Step 2: Set the NVMADRU/NVMADR register pair to point to the correct page of executive memory to be erased.
`0000` `0000` `0000` `0000`	`2xxxx3` `2xxxx4` `884693` `8846A4`	`MOV #DestinationAddress<15:0>, W3` `MOV #DestinationAddress<23:16>, W4` `MOV W3, NVMADR` `MOV W4, NVMADRU`
Step 3: Set the NVMCON register to erase the first page of executive memory.
`0000` `0000` `0000` `0000`	`24003A` `88468A` `000000` `000000`	`MOV #0x4003, W10` `MOV W10, NVMCON` `NOP` `NOP`
Step 4: Initiate the erase cycle.
`0000` `0000` `0000` `0000` `0000` `0000` `0000` `0000`	`200551` `8846B1` `200AA1` `8846B1` `A8F1A1` `000000` `000000` `000000`	`MOV #0x55, W1` `MOV W1, NVMKEY` `MOV #0xAA, W1` `MOV W1, NVMKEY` `BSET NVMCON, #WR` `NOP` `NOP` `NOP`
Step 5: Generate clock pulses for the Page Erase operation to complete until the WR bit is cleared.
`0000` `0000` `0000` `0000` `0000` `0001` `0000` `0000` `0000` `0000` `0000` `0000` `0000` —	`000000` `804680` `000000` `887E60` `000000` `<VISI>` `000000` `000000` `000000` `040200` `000000` `000000` `000000` —	`NOP` `MOV NVMCON, W0` `NOP` `MOV W0, VISI` `NOP` Clock out contents of the VISI register. `NOP` `NOP` `NOP` `GOTO 0x200` `NOP` `NOP` `NOP` Repeat until the WR bit is clear.
Step 6: Repeat Steps 2-5 for all pages of executive memory.