PROGRAMMING AND VERIFYING NONVOLATILE MEMORY

14.6.1 On-chip Code Memory

On-chip code memory is located in the top region of the memory space starting at address FF:0000H. At reset, the 87C251Sx and 83C251Sx devices vector to this address. See Chapter 3, “Address Spaces,” for detailed information on the 8XC251S x address space.

To enter user program code and data in the on-chip code memory, perform the procedure de- scribed in 14.4, “Programming Algorithm,” using the program on-chip code memory mode (Ta- ble 14-1).

To verify that the on-chip code memory is correctly programmed, perform the procedure de- scribed in section 14.5, “Verify Algorithm,” using the verify on-chip code memory mode (Table 14-1).

14.6.2 Configuration Bytes

The 87C251Sx and 83C251Sx store configuration information in an eight-byte configuration ar- ray at FF:FFF8H–FF:FFFFH. UCONFIG0 (FF:FFF8H) and UCONFIG1 (FF:FFF9H) are imple- mented; the remaining bytes are reserved for future use. See Figure 4-1 on page 4-2, Figure 4-3 on page 4-6, and Figure 4-4 on page 4-7.

To program the 87C251Sx configuration bytes, perform the procedure described in 14.4, “Pro- gramming Algorithm,” using the program configuration byte mode (Table 14-1).

To verify the 87C251Sx, 83C251Sx, or 80C251SB, SQ configuration bytes, perform the proce- dure described in 14.5, “Verify Algorithm,” using the verify configuration byte mode (Table 14-1).

14.6.3 Lock Bit System

The 87C251Sx provides a three-level lock system for protecting user program code stored in the on-chip code memory from unauthorized access. On the 83C251Sx, only LB1 protection is avail- able. Table 14-2 describes the levels of protection.

To program the lock bits, perform the procedure described in 14.4, “Programming Algorithm,” using the program lock bits mode (Table 14-1).

To verify that the lock bits are correctly programmed, perform the procedure described in 14.5, “Verify Algorithm,” using the verify lock bits mode (Table 14-1).

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Intel 8XC251SQ, 8XC251SA, 8XC251SP, 8XC251SB, Embedded Microcontroller manual Configuration Bytes, Lock Bit System
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Embedded Microcontroller, 8XC251SP, 8XC251SA, 8XC251SQ, 8XC251SB specifications

The Intel 8XC251 series of embedded microcontrollers is a family of versatile and powerful devices, designed to meet the demands of a wide range of applications. With models such as the 8XC251SB, 8XC251SQ, 8XC251SA, and 8XC251SP, this series offers unique features while maintaining a high level of performance and reliability.

At the heart of the 8XC251 microcontrollers is the 8051 architecture, which provides a 16-bit processor capable of executing complex instructions efficiently. This architecture not only allows for a rich instruction set but also facilitates programming in assembly language and higher-level languages like C, which are essential for developing sophisticated embedded systems.

One of the significant features of the 8XC251 family is its integrated peripherals, including timer/counters, serial communication interfaces, and interrupt systems. These peripherals enable developers to implement timing functions, data communication, and real-time processing, all of which are crucial in modern embedded applications. The 8XC251SB and 8XC251SQ models, for instance, come equipped with multiple I/O ports that allow for interfacing with other devices and systems, enhancing their functionality in various environments.

The memory architecture of the 8XC251 devices is noteworthy, featuring on-chip ROM, RAM, and EEPROM. The on-chip memory allows for fast access times, which is essential for executing programs efficiently. Moreover, the EEPROM serves as non-volatile memory, enabling the storage of configuration settings and important data that must be retained even when power is lost.

In terms of operating voltage, the 8XC251 devices are designed to operate in a wide range, typically between 4.0V and 6.0V. This flexibility makes them suitable for battery-powered applications, where energy efficiency is critical. The power management features, including reduced power modes, further enhance their suitability for portable devices.

Lastly, the 8XC251 series is supported by a wide range of development tools and resources, allowing engineers and developers to streamline the development process. This support, combined with the microcontrollers' robust features, makes the Intel 8XC251 family a reliable choice for various embedded applications, such as industrial automation, automotive systems, and consumer electronics.

Overall, the Intel 8XC251SB, 8XC251SQ, 8XC251SA, and 8XC251SP deliver high performance, versatility, and ease of use, making them a preferred choice for embedded system designers looking to develop efficient and effective solutions.
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