Bits for Controlling Acceptance of Interrupts

CHAPTER 3 CPU

Figure 3.2-3shows how the shift commands change the carry flag.

Figure 3.2-3 Change of the Carrier Flag by the Shift Commands

- Shift to the left (ROLC)		-	Shift to the right (RORC)
bit7	bit0	bit7	bit0
C			C

Note:

The condition code register is part of the program status register (PS), and thus is not allowed to access only the condition code register.

It is uncommon to fetch and use only some of the flag bits directly. Normally, branch instructions (such as BNZ) or decimal adjustment instructions (such as DAA and DAS) use them indirectly. The initial values of these flags specified after the reset operation are undefined.

■Bits for Controlling Acceptance of Interrupts

●Interrupt enable flag (I)

When this flag is "1", interrupts are allowed and the CPU accepts interrupts.

When this flag is "0", interrupts are prohibited and the CPU does not accept interrupts.

The initial value of the interrupt enable flag after the reset operation is "0".

Normally, the SETI instruction sets the interrupt enable flag to "1", and the CLRI instruction sets it to "0" to clear.

●Interrupt level bits (IL1 and IL0)

These bits indicate the level of an interrupt the CPU is accepting, then it is compared with the values in the interrupt level setting registers (ILR1 to 4) which is specified as the level of interrupt requests of peripheral functions (IRQ0 to IRQF).

When the interrupt enable flag is turned on (I = 1), and if an interrupt is requested with an interrupt level value lower than that of these bits, the CPU accepts the interrupt. Table 3.2-1provides interrupt level intensities. The initial value of the interrupt level specified after the reset operation is 11B.

Table 3.2-1 Interrupt Levels

IL1	IL0	Interrupt level	Intensity

0	0	1	High
			High
0	1



1	0	2
1	0	2	Low (no interrupts allowed)

1	1	3
1	1	3

Note:

When the CPU is not handling an interrupt (handling the main program), the interrupt level bits (IL1 and IL0) are normally set to 11B.

For details on interrupts, see Section "3.4 Interrupts ".

F202RA, MB89202 specifications

The Fujitsu MB89202 and F202RA microcontrollers are part of the 16-bit microcontroller family, renowned for their robust performance and versatility in a variety of embedded system applications. These devices are tailored for high-efficiency operation across diverse industries, including automotive, consumer electronics, and industrial automation.

One of the main features of the MB89202 is its powerful CPU core, which operates at a clock speed of up to 20 MHz. This enables the microcontroller to perform complex calculations and consumer-grade applications seamlessly. The architecture is designed to handle multiple tasks effectively, making it suitable for real-time operations.

Memory capacity is a vital characteristic of the MB89202, featuring on-chip RAM and ROM configurations. The microcontroller can accommodate different memory variants, providing developers with flexibility in memory allocation based on their application requirements. This adaptability facilitates applications ranging from simple control systems to complex data processing tasks.

The F202RA variant extends the capabilities of the MB89202 by integrating advanced peripheral functions. It includes built-in timers, A/D converters, and serial communication interfaces, which are essential for interfacing with other hardware components or sensors. The availability of these peripherals reduces the need for additional external circuits, thus contributing to a more compact and cost-effective design.

In terms of power management, the MB89202 series employs advanced power-saving technologies. The microcontroller offers various low-power modes, enabling devices to conserve energy during idle times, making it highly suitable for battery-operated applications. This characteristic not only enhances the efficiency of devices but also extends their operational lifespan.

Moreover, the Fujitsu MB89202 series incorporates robust protection features, including watchdog timers and failure detection mechanisms. These safety features ensure reliable operation in critical systems, making them a preferred choice in applications where failure is not an option.

The MB89202 and F202RA microcontrollers also support a range of development tools and environments, including integrated development environments (IDEs) and software libraries, which facilitate rapid application development. With these tools, developers can efficiently prototype, debug, and optimize their applications.

In summary, the Fujitsu MB89202 and F202RA microcontrollers stand out with their efficient performance, extensive memory options, integrated peripherals, and power-saving capabilities, making them ideal for a wide array of embedded applications. Their reliability and robustness further enhance their attractiveness for designers seeking advanced microcontroller solutions.

Fujitsu MB89202, F202RA Bits for Controlling Acceptance of Interrupts, Interrupt Levels, IL1 IL0

Models: F202RA MB89202