XR16V794 Datasheet, PDF (52/53 Pages) Exar Corporation – HIGH PERFORMANCE 2.25V TO 3.6V QUAD UART WITH FRACTIONAL

XR16V794
HIGH PERFORMANCE 2.25V TO 3.6V QUAD UART WITH FRACTIONAL BAUD RATE
TABLE OF CONTENTS
REV. 1.0.0
GENERAL DESCRIPTION ................................................................................................ 1
APPLICATIONS............................................................................................................................................... 1
FEATURES .................................................................................................................................................... 1
FIGURE 1. BLOCK DIAGRAM ............................................................................................................................................................. 1
FIGURE 2. PIN OUT OF THE DEVICE.................................................................................................................................................. 2
ORDERING INFORMATION................................................................................................................................ 2
PIN DESCRIPTIONS ........................................................................................................ 3
1.0 DESCRIPTION ......................................................................................................................................... 6
2.0 FUNCTIONAL DESCRIPTIONS............................................................................................................... 6
2.1 DEVICE RESET ................................................................................................................................................... 6
2.1.1 HARDWARE RESET....................................................................................................................................................... 6
2.1.2 SOFTWARE RESET ....................................................................................................................................................... 6
2.2 UART CHANNEL SELECTION............................................................................................................................ 6
TABLE 1: UART CHANNEL SELECTION ............................................................................................................................................. 6
2.3 SIMULTANEOUS WRITE TO ALL CHANNELS ................................................................................................. 6
2.4 INT# OUPUT ........................................................................................................................................................ 7
TABLE 2: INT# PIN OPERATION FOR TRANSMITTER ........................................................................................................................... 7
TABLE 3: INT# PIN OPERATION FOR RECEIVER ................................................................................................................................ 7
2.5 CRYSTAL OSCILLATOR / BUFFER................................................................................................................... 7
FIGURE 3. TYPICAL OSCILLATOR CONNECTIONS................................................................................................................................. 7
2.6 PROGRAMMABLE BAUD RATE GENERATOR WITH FRACTIONAL DIVISOR.............................................. 8
FIGURE 4. BAUD RATE GENERATOR ................................................................................................................................................. 8
TABLE 4: TYPICAL DATA RATES WITH A 24 MHZ CRYSTAL OR EXTERNAL CLOCK AT 16X SAMPLING ..................................................... 9
2.7 TRANSMITTER .................................................................................................................................................... 9
2.7.1 TRANSMIT HOLDING REGISTER (THR) - WRITE ONLY ........................................................................................... 10
2.7.2 TRANSMITTER OPERATION IN NON-FIFO MODE .................................................................................................... 10
FIGURE 5. TRANSMITTER OPERATION IN NON-FIFO MODE .............................................................................................................. 10
2.7.3 TRANSMITTER OPERATION IN FIFO MODE ............................................................................................................. 10
FIGURE 6. TRANSMITTER OPERATION IN FIFO AND FLOW CONTROL MODE ..................................................................................... 10
2.8 RECEIVER ......................................................................................................................................................... 11
2.8.1 RECEIVE HOLDING REGISTER (RHR) - READ-ONLY .............................................................................................. 11
FIGURE 7. RECEIVER OPERATION IN NON-FIFO MODE .................................................................................................................... 11
FIGURE 8. RECEIVER OPERATION IN FIFO AND AUTO RTS FLOW CONTROL MODE ......................................................................... 12
2.9 THR AND RHR REGISTER LOCATIONS ......................................................................................................... 12
TABLE 5: TRANSMIT AND RECEIVE HOLDING REGISTER LOCATIONS, 16C550 COMPATIBLE ............................................................... 12
2.10 AUTO RTS/DTR HARDWARE FLOW CONTROL OPERATION.................................................................... 13
2.10.1 AUTO CTS/DSR FLOW CONTROL............................................................................................................................ 13
FIGURE 9. AUTO RTS/DTR AND CTS/DSR FLOW CONTROL OPERATION........................................................................................ 14
2.11 AUTO XON/XOFF (SOFTWARE) FLOW CONTROL...................................................................................... 14
TABLE 6: AUTO XON/XOFF (SOFTWARE) FLOW CONTROL ............................................................................................................... 15
2.12 SPECIAL CHARACTER DETECT .................................................................................................................. 15
2.13 AUTO RS485 HALF-DUPLEX CONTROL ..................................................................................................... 15
2.14 INFRARED MODE ........................................................................................................................................... 15
FIGURE 10. INFRARED TRANSMIT DATA ENCODING AND RECEIVE DATA DECODING .......................................................................... 16
2.15 SLEEP MODE WITH AUTO WAKE-UP.......................................................................................................... 17
2.16 INTERNAL LOOPBACK .................................................................................................................................. 18
FIGURE 11. INTERNAL LOOP BACK ................................................................................................................................................. 18
3.0 XR16V794 REGISTERS ........................................................................................................................ 18
FIGURE 12. THE XR16V794 REGISTERS........................................................................................................................................ 19
3.1 DEVICE CONFIGURATION REGISTER SET .................................................................................. 19
TABLE 7: XR16V794 REGISTER SETS ............................................................................................................................................ 19
TABLE 8: DEVICE CONFIGURATION REGISTERS ............................................................................................................................... 20
3.1.1 THE GLOBAL INTERRUPT SOURCE REGISTERS.................................................................................................... 20
3.1.1.1 INT0 CHANNEL INTERRUPT INDICATOR: ................................................................................................................ 21
3.1.1.2 INT1, INT2 AND INT3 INTERRUPT SOURCE LOCATOR ........................................................................................... 21
FIGURE 13. THE GLOBAL INTERRUPT REGISTERS, INT0, INT1, INT2 AND INT3 .............................................................................. 21
TABLE 9: UART CHANNEL [7:0] INTERRUPT SOURCE ENCODING AND CLEARING .............................................................................. 21
3.1.2 GENERAL PURPOSE 16-BIT TIMER/COUNTER [TIMERMSB, TIMELSB, TIMER, TIMECNTL] (DEFAULT 0XXX-XX-
00-00).............................................................................................................................................................................. 22
3.1.2.1 TIMERMSB [7:0] AND TIMERLSB [7:0] ............................................................................................................. 22
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