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ADE5166 数据表(PDF) 107 Page - Analog Devices |
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ADE5166 数据表(HTML) 107 Page - Analog Devices |
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107 / 156 page  ADE5166/ADE5169/ADE5566/ADE5569 Rev. B | Page 107 of 156 The lower 62 bytes are available to the user for program storage or as nonvolatile data memory. They are segmented into 124 pages of 512 bytes each. It is up to the user to decide which flash memory pages are to be used for data memory. It is recommended that each page be dedicated solely to program or data memory so that an instance does not arise where the program counter is loaded with data memory instead of an opcode from the program memory or where program memory is erased to update a byte of data memory. The flash memory can be protected from read or write/erase access. The protection is implemented in the upper page of user program memory. The last sixteen bytes from this page are used to confi- gure the write/erase protection for each of the pages. The four bytes that remain are used for configuring read protection of the flash memory. The read protection is selected in groups of four pages. Finally, there is a byte used to store the key required for modifying the protection scheme. If any code protection is required, the page of information memory must be write/erase protected at a minimum. Thus, it is recommended that if code protection is enabled, the last page of user accessible flash memory be used only to store data that does not need modification in the field. If the firmware requires protection and may need updating in the future, the last page should be reserved for constants used by the user code that do not require modification during emulation or debug. Page 0 through Page 122 are, therefore, available for general program and data memory use. It is recommended that Page 123 be used for constants or code that do not require future modifica- tions. Note that the last 20 bytes of Page 123 are reserved for the flash memory protection and are, therefore, unavailable to the user. USING THE FLASH MEMORY The 62 bytes of flash memory are configured as 124 pages, each comprising 512 bytes. As with the other ADE5166/ADE5169/ ADE5566/ADE5569 peripherals, the interface to this memory space is via a group of registers mapped in the SFR space. The flash data SFR (EDATA, Address 0xBC), holds the byte of data to be accessed. The byte of flash memory is addressed via the flash high byte address SFR (EADRH, Address 0xC7) and the flash low byte address SFR (EADRL, Address 0xC6). Table 104. Flash SFRs SFR Address Default Bit Addressable Description ECON 0xB9 0x00 No Flash control FLSHKY 0xBA 0xFF No Flash key PROTKY 0xBB 0xFF No Flash protection key EDATA 0xBC 0x00 No Flash data EADRL 0xC6 0x00 No Flash low byte address EADRH 0xC7 0x00 No Flash high byte address ECON is an 8-bit flash control SFR (Address 0xB9) that can be written to with one of five flash memory access commands to trigger various read, write, erase, and verify functions. Figure 94 demonstrates the steps required for access to the flash memory. EADRH FLSHKY EADRL ADDRESS ADDRESS DECODER FLSHKY = 0x3B? PROTECTION DECODER ECON COMMAND ACCESS ALLOWED? FLASH PROTECTION KEY TRUE: ACCESS ALLOWED ECON = 0 FALSE: ACCESS DENIED ECON = 1 Figure 94. Flash Memory Read/Write/Erase Protection Block Diagram |
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