![]() The number of data written on the page may vary from 1 to 128 bytes (the page size). A physical write in the EEPROM memory is done in two steps: write data in the column latches and transfer of all data latches into an EEPROM memory row (programming) after Extract MCU. A read in the EEPROM memory is done with a MOVX instruction. The 1-Kbyte on-chip EEPROM memory block is located at addresses 0000h to 03FFh of the ERAM memory space and is selected by setting control bits in the EECON register before Extract MCU. If all storage is on chip, then byte location 3FFFh (16K) or 7FFFh (32K) should be left vacant to prevent and undesired pre-fetch from external program memory address 4000h (16K) or 8000h (32K) when Extract MCU. If the EA pin is tied low, all program memory fetches are from external memory. Bus expansion for accessing program memory from 16K or 32K upward is automatic since external instruction fetches occur automatically when the program counter exceeds 3FFFh (16K) or 7FFFh (32K) if Extract MCU. When the EA is pin high, the processor fetches instructions from internal program Flash. In the AT89C5131, the lowest 16K or 32K of the 64 Kbyte program memory address space is filled by internal Flash. Several software registers are described in Table 39 after Extract MCU. They are accessed in the following ways before Extract MCU:Ĭommands issued by the parallel memory programmer.Ĭalls of API issued by the application software. This block is also called ”XAF” or eXtra Array Flash. These registers are in the “Extra Flash Memory” part of the Flash memory. These values are used by Atmel ISP (see Section “In-System Programming (ISP)”). Several registers are used, in factory and by parallel programmers, to make copies of hardware registers contents. LB2-0: Security level four to protect the code from a parallel access with maximum security. OSCON1-0: Set to start with 32 MHz oscillator configuration value. X2: Set to force X1 mode (Standard Mode) if Extract MCU The default value of the HSB provides parts ready to be programmed with ISP: The part reference can always be read using Flash parallel programming modes. This will set the HSB in its inactive state and will erase the Flash memory. To load a new application with the parallel programmer, a chip erase must be done first. The code access through the ISP is still possible and is controlled by the “software security bits” which are stored in the extra Flash memory accessed by the ISP firmware when Extract MCU. These security bits protect the code access through the parallel programming interface. We can Extract IC AT89C5131 Code, please view the MCU AT89C5131 features for your reference: ![]()
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