PROGRAMMABLE COUNTER ARRAY

9.3PCA COMPARE/CAPTURE MODULES

Each compare/capture module is made up of a compare/capture register pair (CCAPxH/CCAPxL), a 16-bitcomparator, and various logic gates and signal transition selectors. The registers store the time or count at which an external event occurred (capture) or at which an action should occur (comparison). In the PWM mode, the low-byte register controls the duty cy- cle of the output waveform.

The logical configuration of a compare/capture module depends on its mode of operation (Figures 9-2 through 9-5). Each module can be independently programmed for operation in any of the following modes:

•16-bit capture mode with triggering on the positive edge, negative edge, or either edge.

•Compare modes: 16-bit software timer, 16-bit high-speed output, 16-bit WDT (module 4 only), or 8-bit pulse width modulation.

•No operation.

Bit combinations programmed into a compare/capture module’s mode register (CCAPMx) deter- mine the operating mode. Figure 9-9 provides bit definitions and Table 9-3 lists the bit combina- tions of the available modes. Other bit combinations are invalid and produce undefined results.

The compare/capture modules perform their programmed functions when their common time base, the PCA timer/counter, runs. The timer/counter is turned on and off with the CR bit in the CCON register. To disable any given module, program it for the no operation mode. The occur- rence of a capture, software timer, or high-speed output event in a compare/capture module sets the module’s compare/capture flag (CCFx) in the CCON register and generates a PCA interrupt request if the corresponding enable bit in the CCAPMx register is set.

The CPU can read or write the CCAPxH and CCAPxL registers at any time.

9.3.116-bit Capture Mode

The capture mode (Figure 9-2) provides the PCA with the ability to measure periods, pulse widths, duty cycles, and phase differences at up to five separate inputs. External I/O pins CEX0 through CEX4 are sampled for signal transitions (positive and/or negative as specified). When a compare/capture module programmed for the capture mode detects the specified transition, it captures the PCA timer/counter value. This records the time at which an external event is detect- ed, with a resolution equal to the timer/counter clock period.

9-5

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Intel Embedded Microcontroller, 8XC251SA, 8XC251SP, 8XC251SQ, 8XC251SB PCA COMPARE/CAPTURE Modules, 1 16-bit Capture Mode
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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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