81C17 Datasheet, PDF (4/18 Pages) SMSC Corporation – TWENTY PIN UART (TPUART)

D0-D7
nCS
nRD
nWR
RS
DATA
BUS
TRANS
READ
WRITE
DECODE
LOGIC
nINT
VCC
GND
MASK
REGISTER
& LOGIC
CONTROL
REGISTER
TRANSMIT
BUFFER
TRANSMIT
TX
SHIFT REGISTER
MODE
REGISTER
TRANSMIT
CONTROL
BAUD
RATE
SELECT
REGISTER
BAUD
RATE
GENERATOR
STATUS
REGISTER
RECEIVE
CONTROL
RECEIVE
SHIFT REGISTER
RECEIVE
BUFFER
CLOCK
RX
FIGURE 2 – COM81C17 BLOCK DIAGRAM
1800 OHM
560 OHM
7404
220 OHM
7404
7404
7404
220 OHM
30 pF
5.0688 MHz
FIGURE 2A – 5.0688 MHz CRYSTAL OSCILLATOR CIRCUIT
4