XR16M2551 Datasheet, PDF (50/51 Pages) Exar Corporation – HIGH PERFORMANCE LOW VOLTAGE DUART WITH 16-BYTE FIFO AND POWERSAVE FEATURE

XR16M2551
HIGH PERFORMANCE LOW VOLTAGE DUART WITH 16-BYTE FIFO AND POWERSAVE FEATURE
TABLE OF CONTENTS
REV. 1.0.2
GENERAL DESCRIPTION ................................................................................................ 1
APPLICATIONS............................................................................................................................................... 1
FEATURES .................................................................................................................................................... 1
FIGURE 1. XR16M2551 BLOCK DIAGRAM ........................................................................................................................................ 1
FIGURE 2. PIN OUT ASSIGNMENT ..................................................................................................................................................... 2
ORDERING INFORMATION................................................................................................................................ 2
PIN DESCRIPTIONS ........................................................................................................ 3
1.0 PRODUCT DESCRIPTION....................................................................................................................... 7
2.0 FUNCTIONAL DESCRIPTIONS............................................................................................................... 8
2.1 CPU INTERFACE................................................................................................................................................. 8
FIGURE 3. XR16M2551 TYPICAL INTEL/MOTOROLA DATA BUS INTERCONNECTIONS .......................................................................... 8
2.2 DEVICE RESET ................................................................................................................................................... 8
2.3 DEVICE IDENTIFICATION AND REVISION........................................................................................................ 9
2.4 CHANNEL A AND B SELECTION....................................................................................................................... 9
TABLE 1: CHANNEL A AND B SELECT IN 16 MODE ............................................................................................................................ 9
TABLE 2: CHANNEL A AND B SELECT IN 68 MODE ............................................................................................................................ 9
2.5 CHANNEL A AND B INTERNAL REGISTERS ................................................................................................... 9
2.6 DMA MODE........................................................................................................................................................ 10
TABLE 3: TXRDY# AND RXRDY# OUTPUTS IN FIFO AND DMA MODE ........................................................................................... 10
2.7 INTA AND INTB OUTPUTS ............................................................................................................................... 10
TABLE 4: INTA AND INTB PINS OPERATION FOR TRANSMITTER ...................................................................................................... 10
TABLE 5: INTA AND INTB PIN OPERATION FOR RECEIVER ............................................................................................................. 10
2.8 CRYSTAL OSCILLATOR OR EXTERNAL CLOCK INPUT .............................................................................. 11
FIGURE 4. TYPICAL CRYSTAL CONNECTIONS ................................................................................................................................... 11
2.9 PROGRAMMABLE BAUD RATE GENERATOR WITH FRACTIONAL DIVISOR............................................ 11
FIGURE 5. BAUD RATE GENERATOR ............................................................................................................................................... 12
TABLE 6: TYPICAL DATA RATES WITH A 24 MHZ CRYSTAL OR EXTERNAL CLOCK AT 16X SAMPLING ................................................... 13
2.10 TRANSMITTER ................................................................................................................................................ 13
2.10.1 TRANSMIT HOLDING REGISTER (THR) - WRITE ONLY ......................................................................................... 14
2.10.2 TRANSMITTER OPERATION IN NON-FIFO MODE .................................................................................................. 14
FIGURE 6. TRANSMITTER OPERATION IN NON-FIFO MODE .............................................................................................................. 14
2.10.3 TRANSMITTER OPERATION IN FIFO MODE ........................................................................................................... 14
FIGURE 7. TRANSMITTER OPERATION IN FIFO AND FLOW CONTROL MODE ..................................................................................... 14
2.11 RECEIVER ....................................................................................................................................................... 15
2.11.1 RECEIVE HOLDING REGISTER (RHR) - READ-ONLY ............................................................................................ 15
FIGURE 8. RECEIVER OPERATION IN NON-FIFO MODE .................................................................................................................... 15
FIGURE 9. RECEIVER OPERATION IN FIFO AND AUTO RTS FLOW CONTROL MODE ......................................................................... 16
2.12 AUTO RTS (HARDWARE) FLOW CONTROL ................................................................................................ 16
2.13 AUTO RTS HYSTERESIS............................................................................................................................... 17
TABLE 7: AUTO RTS (HARDWARE) FLOW CONTROL ........................................................................................................................ 17
2.14 AUTO CTS FLOW CONTROL ........................................................................................................................ 17
FIGURE 10. AUTO RTS AND CTS FLOW CONTROL OPERATION....................................................................................................... 18
2.15 AUTO XON/XOFF (SOFTWARE) FLOW CONTROL...................................................................................... 19
TABLE 8: AUTO XON/XOFF (SOFTWARE) FLOW CONTROL ............................................................................................................... 19
2.16 SPECIAL CHARACTER DETECT .................................................................................................................. 19
2.17 INFRARED MODE ........................................................................................................................................... 20
FIGURE 11. INFRARED TRANSMIT DATA ENCODING AND RECEIVE DATA DECODING .......................................................................... 20
2.18 SLEEP MODE WITH WAKE-UP INDICATOR AND POWERSAVE FEATURE............................................. 20
2.18.1 SLEEP MODE ............................................................................................................................................................. 21
2.18.2 POWERSAVE FEATURE............................................................................................................................................ 21
2.19 INTERNAL LOOPBACK ................................................................................................................................. 22
FIGURE 12. INTERNAL LOOP BACK IN CHANNEL A AND B ................................................................................................................ 22
3.0 UART INTERNAL REGISTERS ............................................................................................................. 23
TABLE 9: UART CHANNEL A AND B UART INTERNAL REGISTERS ....................................................................................... 23
TABLE 10: INTERNAL REGISTERS DESCRIPTION. SHADED BITS ARE ENABLED WHEN EFR BIT-4=1 ....................................... 24
4.0 INTERNAL REGISTER DESCRIPTIONS............................................................................................... 25
4.1 RECEIVE HOLDING REGISTER (RHR) - READ- ONLY .................................................................................. 25
4.2 TRANSMIT HOLDING REGISTER (THR) - WRITE-ONLY ............................................................................... 25
4.3 INTERRUPT ENABLE REGISTER (IER) - READ/WRITE................................................................................. 25
I