EXTERNAL MEMORY INTERFACE

 

WCON

 

 

 

 

 

 

 

 

 

 

Address:

S:A7H

 

 

 

 

 

 

 

 

 

 

 

 

 

Reset State:

XXXX XX00B

 

 

7

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

—

—

 

—

 

—

 

 

—

 

—

RTWCE

RTWE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

Bit

 

 

 

 

 

 

Function

 

 

 

 

Number

Mnemonic

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7:2

—

Reserved:

 

 

 

 

 

 

 

 

 

 

 

 

 

The values read from these bits are indeterminate. Write “0” to these

 

 

 

 

 

bits.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

RTWCE

Real-time WAIT CLOCK enable. Write a ‘1’ to this bit to enable the WAIT

 

 

 

 

 

CLOCK on port 1.7 (WCLK). The square wave output signal is one-half

 

 

 

 

 

the oscillator frequency.

 

 

 

 

 

 

 

 

 

 

 

 

0

RTWE

Real-time WAIT# enable. Write a ‘1’ to this bit to enable real-time wait-

 

 

 

 

 

state input on port 1.6 (WAIT#).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 13-11. Real-time Wait State Control Register (WCON)

NOTE

The WAIT# and WCLK signals are alternate functions for the port 1.6:7 input and output buffers. Use of other alternate functions may conflict with wait state operation.

When WAIT# is enabled, PCA module 3 is disabled and resumes operation only when the WAIT# function is disabled. The same relationship exists between WCLK and PCA module 4. It is not advisable to alternate between PCA operations and real-time wait-state operations at port 1.6 (CEX3/WAIT#) or port 1.7 (CEX4/WCLK).

Port 1.7 can also be enabled to drive address signal A17 in some memory designs. The A17 address signal always takes priority over other alternate functions (in this case, both PCA.4 and WCLK). Even if RTWCE is enabled in WCON.1, the WCLK output does not appear during bus cycles enabled to drive address A17. The use of WAIT# as an input on port 1.6 is unaffected by address signals.

13-11

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Intel Embedded Microcontroller, 8XC251SA, 8XC251SP, 8XC251SQ, 8XC251SB manual Wcon, SA7H, Xxxx XX00B Rtwce Rtwe
Page 218 Page 220

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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