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Intel Embedded Microcontroller, 8XC251SA manual Interrupt Handler, On-chip Code Memory, On-chip RAM

Models: Embedded Microcontroller 8XC251SP 8XC251SA 8XC251SQ 8XC251SB

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ARCHITECTURAL OVERVIEW

2.2.3Interrupt Handler

The interrupt handler can receive interrupt requests from eleven sources: seven maskable sources and the TRAP instruction. When the interrupt handler grants an interrupt request, the CPU dis- continues the normal flow of instructions and branches to a routine that services the source that requested the interrupt. You can enable or disable the interrupts individually (except for TRAP) and you can assign one of four priority levels to each interrupt. See Chapter 6, “Interrupt System,” for a detailed description.

2.2.4On-chip Code Memory

For 83C251SA (ROM) and 87C251SA (OTPROM/EPROM) devices, memory locations FF:0000H–FF:1FFFH are implemented with 8-Kbytes of on-chip code memory. For 83C251SB and 87C251SB devices, memory locations FF:0000H–FF:3FFFH are implemented with 16- Kbytes of on-chip code memory.

Following a reset, the first instruction is fetched from location FF:0000H. For 80C251Sx (no ROM/OTPROM/EPROM) devices, location FF:0000H is always in external memory.

2.2.5On-chip RAM

The 8XC251SA and 8XC251SB have 1-Kbyte of on-chip data RAM at locations 20H–41FH. The 8XC251SP and 8XC251SQ have 512 bytes of on-chip data RAM at locations 20H–21FH. These RAM locations can be accessed with direct, indirect, and displacement addressing. Ninety-six of these locations (20H–7FH) are bit addressable. An additional 32 bytes of on-chip RAM (00H– 1FH) provide storage for the four banks of registers R0–R7.

2.3ON-CHIP PERIPHERALS

The on-chip peripherals, which lie outside the core, perform specialized functions. Software ac- cesses the peripherals via their special function registers (SFRs). The 8XC251Sx has four periph- erals: the watchdog timer, the timer/counters, the programmable counter array (PCA), and the serial I/O port.

2.3.1Timer/Counters and Watchdog Timer

The timer/counter unit has three timer/counters, which can be clocked by the oscillator (for timer operation) or by an external input (for counter operation). You can set up an 8-bit, 13-bit, or 16- bit timer/counter, and you can program them for special applications, such as capturing the time of an event on an external pin, outputting a programmable clock signal on an external pin, or gen- erating a baud rate for the serial I/O port. Timer/counter events can generate interrupt requests.

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Intel Embedded Microcontroller, 8XC251SA, 8XC251SP Interrupt Handler, On-chip Code Memory, On-chip RAM, ON-CHIP Peripherals
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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.