III

8xC251Tx Hardware Description

8xC251TA, 8xC251TB, 8xC251TP, 8xC251TQ, Hardware Description

Addendum to the 8xC251SA, 8xC251SB, 8xC251SP, 8xC251SQ, User’s Manual

1.0 INTRODUCTION TO THE 8xC251Tx

1.1

Comparing the 8xC251Tx and 8xC251Sx ..................................................................... 1

2.0 SIGNAL SUMMARY

3.0 THE SECOND SERIAL I/O PORT

3.1

Overview........................................................................................................................ 7

3.2

Special Function Register Definitions ............................................................................ 9

3.2.1

SCON1 .................................................................................................................... 9

3.2.2

SBUF1 ................................................................................................................... 10

3.2.3

SADDR1 ................................................................................................................ 10

3.2.4

SADEN1 ................................................................................................................ 10

3.2.5

BGCON .................................................................................................................. 10

3.2.6

IE1 ......................................................................................................................... 11

3.2.7

IPH1 ....................................................................................................................... 11

3.2.8

IPL1 ....................................................................................................................... 11

4.0 EXTENDED DATA FLOAT TIMING

4.1

Summary of the Extended Data Float Timing Changes .............................................. 12

FIGURES

Figure 1

8xC251Tx Block Diagram ..................................................................................... 1

TABLES

Table 1.

8xC251Tx Signal Summary ................................................................................. 2

Table 2.

8xC251Tx Signal Descriptions ............................................................................. 3

Table 3.

Special Function Register (SFR) Map.................................................................. 6

Table 4.

Second Serial I/O Port Signals ............................................................................ 7

Table 5.

Second Serial I/O Port Special Function Registers.............................................. 8

Table 6.

SCON1 Special Function Register Definitions ..................................................... 9

Table 7.

BGCON Special Function Register Definitions .................................................. 10

Table 8.

IE1 Special Function Register Definitions .......................................................... 11

Table 9.

IPH1 Special Function Register Definitions ....................................................... 11

Table 10.

IPL1 Special Function Register Definitions ........................................................ 11

Table 11.

Interrupt Priority of Second Serial I/O Port......................................................... 11

Table 12.

UCONFIG1 bit definitions for the 8xC251Tx ...................................................... 12

Table 13.

Summary of the EDF# and WSB#[1:0] Configuration Options........................... 13