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Intel 8XC251SB, 8XC251SA, 8XC251SP, 8XC251SQ manual Configuration Byte BUS Cycles, Nonpage Mode

Models: Embedded Microcontroller 8XC251SP 8XC251SA 8XC251SQ 8XC251SB

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EXTERNAL MEMORY INTERFACE

13.6 CONFIGURATION BYTE BUS CYCLES

If EA# = 0, devices obtain configuration information from a configuration array in external mem- ory. This section describes the bus cycles executed by the reset routine to fetch user configuration bytes from external memory. Configuration bytes are discussed in Chapter 4, “Device Configu- ration.”

To determine whether the external memory is set up for page mode or nonpage mode operation, the 8XC251Sx accesses external memory using internal address FF:FFF8H (UCONFIG0). See states 1–4 in Figure 13-16. If the external memory is set up for page mode, it places UCONFIG0 on P2 as D7:0, overwriting A15:8 (FFH). If external memory is set up for nonpage mode, A15:8 is not overwritten. The 8XC251Sx examines P2 bit 1. Subsequent configuration byte fetches are in page mode if P2.1 = 0 and in nonpage mode if P2.1 = 1. The 8XC251Sx fetches UCONFIG0 again (states 5–8 in Figure 13-16) and then UCONFIG1 via internal address FF:FFF9H.

The configuration byte bus cycles always execute with ALE extended and one PSEN# wait state.

State 1

State 2

State 3

State 4

State 5

State 6

State 7

State 8

XTAL

ALE

PSEN#

P0

A7:0 = F8H

A7:0 = F8H

A7:0 = F8H

 

P2

A15:8 = FFH

D7:0

A15:8 = FFH

D7:0

 

 

Page Mode

 

 

 

 

P0

A7:0 = F8H

D7:0

 

 

P2

A15:8 = FFH

 

Nonpage Mode

A4228-01

Figure 13-16. Configuration Byte Bus Cycles

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Intel 8XC251SB, 8XC251SA, 8XC251SP, 8XC251SQ, Embedded Microcontroller manual Configuration Byte BUS Cycles, Nonpage 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.