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PIC12F1501-I 数据表(PDF) 89 Page - Microchip Technology |
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PIC12F1501-I 数据表(HTML) 89 Page - Microchip Technology |
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89 / 278 page  2011 Microchip Technology Inc. Preliminary DS41615A-page 89 PIC12(L)F1501 10.2.4 WRITING TO FLASH PROGRAM MEMORY Program memory is programmed using the following steps: 1. Load the address in PMADRH:PMADRL of the row to be programmed. 2. Load each write latch with data. 3. Initiate a programming operation. 4. Repeat steps 1 through 3 until all data is written. Before writing to program memory, the word(s) to be written must be erased or previously unwritten. Pro- gram memory can only be erased one row at a time. No automatic erase occurs upon the initiation of the write. Program memory can be written one or more words at a time. The maximum number of words written at one time is equal to the number of write latches. See Figure 10-5 (row writes to program memory with 16 write latches) for more details. The write latches are aligned to the Flash row address boundary defined by the upper 11-bits of PMADRH:PMADRL, (PMADRH<6:0>:PMADRL<7:4>) with the lower 4-bits of PMADRL, (PMADRL<3:0>) determining the write latch being loaded. Write opera- tions do not cross these boundaries. At the completion of a program memory write operation, the data in the write latches is reset to contain 0x3FFF. The following steps should be completed to load the write latches and program a row of program memory. These steps are divided into two parts. First, each write latch is loaded with data from the PMDATH:PMDATL using the unlock sequence with LWLO = 1. When the last word to be loaded into the write latch is ready, the LWLO bit is cleared and the unlock sequence executed. This initiates the programming operation, writing all the latches into Flash program memory. 1. Set the WREN bit of the PMCON1 register. 2. Clear the CFGS bit of the PMCON1 register. 3. Set the LWLO bit of the PMCON1 register. When the LWLO bit of the PMCON1 register is ‘1’, the write sequence will only load the write latches and will not initiate the write to Flash program memory. 4. Load the PMADRH:PMADRL register pair with the address of the location to be written. 5. Load the PMDATH:PMDATL register pair with the program memory data to be written. 6. Execute the unlock sequence (Section 10.2.2 “Flash Memory Unlock Sequence”). The write latch is now loaded. 7. Increment the PMADRH:PMADRL register pair to point to the next location. 8. Repeat steps 5 through 7 until all but the last write latch has been loaded. 9. Clear the LWLO bit of the PMCON1 register. When the LWLO bit of the PMCON1 register is ‘0’, the write sequence will initiate the write to Flash program memory. 10. Load the PMDATH:PMDATL register pair with the program memory data to be written. 11. Execute the unlock sequence (Section 10.2.2 “Flash Memory Unlock Sequence”). The entire program memory latch content is now written to Flash program memory. An example of the complete write sequence is shown in Example 10-3. The initial address is loaded into the PMADRH:PMADRL register pair; the data is loaded using indirect addressing. Note: The special unlock sequence is required to load a write latch with data or initiate a Flash programming operation. If the unlock sequence is interrupted, writing to the latches or program memory will not be initiated. Note: The program memory write latches are reset to the blank state (0x3FFF) at the completion of every write or erase operation. As a result, it is not necessary to load all the program memory write latches. Unloaded latches will remain in the blank state. |
类似零件编号 - PIC12F1501-I |
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类似说明 - PIC12F1501-I |
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