8XC251SA, SB, SP, SQ USER’S MANUAL

JNC rel

Function: Jump if carry not set

Description: If the CY flag is clear, branch to the address specified; otherwise proceed with the next instruction. The branch destination is computed by adding the signed relative displacement in the second instruction byte to the PC, after incrementing the PC twice to point to the next instruction. The CY flag is not modified.

Flags:

CY

AC

OV

N

Z

 

 

 

 

 

!

—

—

—

—

 

 

 

 

 

Example: The CY flag is set. The instruction sequence

JNC LABEL1

CPL CY

JNC LABEL2

clears the CY flag and causes program execution to continue at label LABEL2.

 

Binary Mode

 

Source Mode

 

 

Not Taken

Taken

 

Not Taken

Taken

Bytes:

2

2

2

 

2

States:

1

4

1

 

4

[Encoding]

 

 

 

 

 

 

0 1 0 1

0 0 0 0

 

rel. addr

 

 

 

 

 

 

 

 

 

Hex Code in: Binary Mode = [Encoding]

Source Mode = [Encoding]

Operation: JNC

(PC) ← (PC) + 2 IF (CY) = 0

THEN (PC) ← (PC) + rel

JNE rel

Function: Jump if not equal

Description: If the Z flag is clear, branch to the address specified; otherwise proceed with the next instruction. The branch destination is computed by adding the signed relative displacement in the second instruction byte to the PC, after incrementing the PC twice.

Flags:

 

CY

AC

OV

N

Z

 

 

 

 

 

 

 

—

—

—

—

!

Example:

 

 

 

 

 

The instruction

 

 

 

 

 

JNE LABEL1

 

 

 

 

causes program execution to continue at LABEL1 if the Z flag is clear.

A-72

Page 323 Page 325
Page 324
Image 324
Intel Embedded Microcontroller, 8XC251SA, 8XC251SP, 8XC251SQ manual JNC rel, JNC LABEL1 CPL CY JNC LABEL2, JNE rel, JNE LABEL1
Page 323 Page 325

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.
Top Page Image Contents