8XC251SA, SB, SP, SQ USER’S MANUAL

8.7.2Using the WDT

To use the WDT to recover from software malfunctions, the user program should control the WDT as follows:

1.Following device reset, write the two-byte sequence 1EH-E1H to the WDTRST register to enable the WDT. The WDT begins counting from 0.

2.Repeatedly for the duration of program execution, write the two-byte sequence 1EH-E1H to the WDTRST register to clear and enable the WDT before it overflows. The WDT starts over at 0.

If the WDT overflows, it initiates a device reset (see section 11.4, “Reset”). Device reset clears the WDT and disables it.

8.7.3WDT During Idle Mode

Operation of the WDT during the power reduction modes deserves special attention. The WDT continues to count while the microcontroller is in idle mode. This means the user must service the WDT during idle. One approach is to use a peripheral timer to generate an interrupt request when the timer overflows. The interrupt service routine then clears the WDT, reloads the peripheral timer for the next service period, and puts the microcontroller back into idle.

8.7.4WDT During PowerDown

The powerdown mode stops all phase clocks. This causes the WDT to stop counting and to hold its count. The WDT resumes counting from where it left off if the powerdown mode is terminated by INT0/INT1. To ensure that the WDT does not overflow shortly after exiting the powerdown mode, clear the WDT just before entering powerdown. The WDT is cleared and disabled if the powerdown mode is terminated by a reset.

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Intel 8XC251SQ, 8XC251SA, 8XC251SP, 8XC251SB manual Using the WDT, WDT During Idle Mode, WDT During PowerDown
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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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