SYMBOL
IRQ_D
IRQ_E
IRQ_F
XTAL1
XTAL2
PIN
37
23
99
7
8
I/O
OUT
12t
OUT
12t
OUT
12t
CLK IN
CLK
OUT
IN
t
IN
t
IN
t
IN
t
IN
t
IN
t
IN
t
IN
t
IN
t
IN
t
O
8tc
I
8tc
FUNCTION
Interrupt request signal D
Interrupt request signal E
Interrupt request signal F
XTAL oscillator input
XTAL oscillator output
SERIAL PORT INTERFACE
Clear To Send is the modem control input.
The function of these pins can be tested by reading Bit 4 of the
handshake status register.
Data Set Ready. An active low indicates the modem or data set is
ready to establish a communication link and transfer data to the
UART.
Data Carrier Detect. An active low indicates the modem or data set
has detected a data carrier.
Ring Indicator. An active low indicates that a ring signal is being
received by the modem or data set.
Serial Input. Used to receive serial data from the communication
link.
UART A Serial Output. Used to transmit serial data out to the
communication link.
During power-on reset, this pin is pulled up internally and is defined
as PIN2IPSEL, which provides the power-on value for CR16 bit 1
(PIN2IPSEL). A 4.7 k is recommended when intends to pull down
at power-on reset.
UART B Serial Output. Used to transmit serial data out to the
communication link.
During power-on reset, this pin is pulled down internally and is
defined as PGMDRQ, which provides the power-on value for CR16
bit 3 (GMDRQ). A 4.7 k is recommended when intends to pull up
at power-on reset.
UART A Data Terminal Ready. An active low informs the modem
or data set that the controller is ready to communicate.
During power-on reset, this pin is pulled down internally and is
defined as PHEFRAS, which provides the power-on value for CR16
bit 0 (HEFRAS). A 4.7 k is recommended when intends to pull up
at power-on reset.
UART B Data Terminal Ready. An active low informs the modem
or data set that controller is ready to communicate.
UART A Request To Send. An active low informs the modem or
data set that the controller is ready to send data.
During power-on reset, this pin is pulled up internally and is defined
as PPNPCVS, which provides the power-on value for CR16 bit 2
(PNPCVS). A 4.7 k is recommended when intends to pull down
at power-on reset.
8
nCTSA
nCTSB
nDSRA
nDSRB
nDCDA
nDCDB
nRIA
nRIB
SINA
SINB/
IRRX1
SOUTA
PIN2IPSEL
34
47
33
48
32
49
31
50
30
42
38
SOUTB
IRTX1
PGMDRQ
43
O
8tc
O
8tc
I
8tc
nDTRA
PHEFRAS
35
O
8tc
I
8tc
nDTRB
nRTSA
PPNPCVS
46
36
O
8t
O
8tc
I
8tc
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