The 8XC251TA, TB, TP, TQ (referred to collectively as the 8XC251Tx) embedded microcontroller has joined the 8XC251SA, SB, SP, SQ (referred to collectively as the 8XC251Sx) as a member of the MCSò 251 microcontroller family. The 8XC251Tx is pin and code compatible with the 8XC251Sx. It also has additional features that the 8XC251Sx does not possess.
This document addresses the differences between the 8XC251Sx and the 8XC251Tx. It also addresses the implications of these differences for a user who is migrating from an existing 8XC251Sx design to an 8XC251Tx design. For a detailed description of the MCS 251 microcontroller core, and standard peripherals that are shared by both the 8XC251Sx and 8XC251Tx, please refer to the 8XC251SA, 8XC251SB, 8XC251SP, 8XC251SQ Embedded Microcontroller User’s Manual (order number 272795).
1.0 Introduction .5
1.1 References ..5
1.2 Comparing the 8XC251Sx and 8XC251Tx6
2.0 The Second Serial I/O Port .6
2.1 Overview .....6
2.2 Hardware Implications.....8
2.3 Software Implications 8
2.3.1 SCON1.......9
2.3.2 SBUF1......10
2.3.3 SADDR1...10
2.3.4 SADEN1 ...10
2.3.5 BGCON ....10
2.3.6 IE1 11
2.3.7 IPH1 11
2.3.8 IPL1 .11
3.0 Extended Data Float Timing .......12
3.1 Summary of the Extended Data Float Timing Changes .12
Tables
1 Second Serial I/O Port Signals.....7
2 Second Serial I/O Port Special Function Registers7
3 Second Serial I/O Priorities ........11
4 UCONFIG1 Bit Definitions for the 8XC251Tx.......12
5 Summary of the EDF# and WSB#[1:0] Configuration Options..13