Motorola MC68306 User Manual page 8

TABLE OF CONTENTS (Continued)
Paragraph Page
Number Title Number
6.2.8.1 RTSB ................................................................................................................ 6-6
6.2.8.2 OP1................................................................................................................... 6-6
6.2.9 Channel A Clear-To-Send (CTSA/IP0) ................................................................ 6-6
6.2.9.1 CTSA ................................................................................................................ 6-6
6.2.9.2 IP0 .................................................................................................................... 6-6
6.2.10 Channel B Clear-To-Send (CTSB/IP1) .............................................................. 6-6
6.2.10.1 CTSB .............................................................................................................. 6-6
6.2.10.2 IP1 .................................................................................................................. 6-6
6.3 Operation ................................................................................................................ 6-7
6.3.1 Baud Rate Generator........................................................................................... 6-7
6.3.2 Transmitter and Receiver Operating Modes ........................................................ 6-7
6.3.2.1 Transmitter ........................................................................................................ 6-9
6.3.2.2 Receiver............................................................................................................ 6-10
6.3.2.3 FIFO Stack ........................................................................................................ 6-11
6.3.3 Looping Modes .................................................................................................... 6-13
6.3.3.1 Automatic Echo Mode....................................................................................... 6-13
6.3.3.2 Local Loopback Mode....................................................................................... 6-13
6.3.3.3 Remote Loopback Mode ................................................................................... 6-13
6.3.4 Multidrop Mode .................................................................................................... 6-14
6.3.5 Counter/Timer ...................................................................................................... 6-16
6.3.5.1 Counter Mode ................................................................................................... 6-16
6.3.5.2 Timer Mode....................................................................................................... 6-16
6.3.6 Bus Operation ...................................................................................................... 6-17
6.3.6.1 Read Cycles ................................................................................................ ..... 6-17
6.3.6.2 Write Cycles...................................................................................................... 6-17
6.3.6.3 Interrupt Acknowledge Cycles .......................................................................... 6-17
6.4 Register Description and Programming .................................................................. 6-17
6.4.1 Register Description ............................................................................................ 6-17
6.4.1.1 Mode Register 1 (DUMR1) ............................................................................... 6-18
6.4.1.2 Mode Register 2 (DUMR2) ............................................................................... 6-20
6.4.1.3 Status Register (DUSR).................................................................................... 6-22
6.4.1.4 Clock-Select Register (DUCSR) ....................................................................... 6-24
6.4.1.5 Command Register (DUCR) ............................................................................. 6-26
6.4.1.6 Receiver Buffer (DURB) ................................................................................... 6-29
6.4.1.7 Transmitter Buffer (DUTB) ................................................................................ 6-29
6.4.1.8 Input Port Change Register (DUIPCR) ............................................................. 6-29
6.4.1.9 Auxiliary Control Register (DUACR) ................................................................ 6-30
6.4.1.10 Interrupt Status Register (DUISR) .................................................................. 6-31
6.4.1.11 Interrupt MASK Register (DUIMR).................................................................. 6-33
6.4.1.12 Count Register Current MSB of Counter (DUCUR) ........................................ 6-33
6.4.1.13 Count Register Current LSB of Counter (DUCLR) ......................................... 6-33
6.4.1.14 Counter/Timer Upper Preload Register (CTUR) ............................................. 6-34
MOTOROLA MC68306 USER'S MANUAL ix