SC28L202 Philips Semiconductors, SC28L202 Datasheet - Page 9

• Manufacturer Part Number: SC28L202
• Description: Dual universal asynchronous receiver/transmitter DUART
• Manufacturer: Philips Semiconductors

Philips Semiconductors
PIN CONFIGURATION FOR 80XXX BUS INTERFACE (INTEL)
2000 Feb 10
Symbol
I/M
D0–D7
CEN
WRN
RDN
A6–A0
RESET
IRQN
X1 / Sclk
X2
RxD A
RxD B
TxD A
TxD B
I/O[7:0]A
I/O[7:0}B
Vcc
GND
Dual UART
Pin
type
I
I/O
I
I
I
I
I
O
I
O
I
I
O
O
I/O
I/O
Power
Power
Name and Function
Bus Configuration: When high or not connected configures the bus interface to the Conditions shown in this table.
Data Bus: Bi–directional 3–State data bus used to transfer commands, data and status between the DUART and
the CPU. D0 is the least significant bit.
Chip Enable: Active–Low input signal. When Low, data transfers between the CPU and the DUART are enabled on
D0–D7 as controlled by the WRN, RDN and A6–A0 inputs. When High, places the D0–D7 lines in the 3–State
condition.
Write Strobe: When Low and CEN is also Low, the contents of the data bus is loaded into the addressed register.
The transfer occurs on the rising edge of the signal.
Read Strobe: When Low and CEN is also Low, causes the contents of the addressed register to be presented on
the data bus. The read cycle begins on the falling edge of RDN.
Address Inputs: Select the DUART internal registers and ports for read/write operations.
Reset: A High level clears internal registers (SR A, SR B, IMR, ISR, OPR, OPCR), places I/O[7:0] A and B at high
impedance input state, stops the counter/timer, and puts Channels A and B in the inactive state, with the TxD A and
TxD B outputs in the mark (High) state. Sets MR pointer to MR1 9600 baud, 1 start, no parity and 1 stop bit(s). (See
Reset table)
Interrupt Request: Active–Low, open–drain, output which signals the CPU that one or more of the eighteen (18)
maskable interrupting conditions are true.
Crystal 1: Crystal or external clock input. A crystal or clock of the specified limits must be supplied at all times.
When a crystal is used, a capacitor must be connected from this pin to ground (see Figure 9).
Crystal 2: Connection for other side of the crystal. When a crystal is used, a capacitor must be connected from this
pin to ground (see Figure 9). If X1/Sclk is driven from an external source, this pin must be open or not driving more
that 2 CMOS or TTL loads.
Channel A Receiver Serial Data Input: The least significant bit is received first. “Mark” is High; “space” is Low.
Channel B Receiver Serial Data Input: The least significant bit is received first. “Mark” is High; “space” is Low.
Channel A Transmitter Serial Data Output: The least significant bit is transmitted first. This output is held in the
“mark” condition when the transmitter is disabled, idle or when operating in local loop back mode. “Mark” is High;
“space” is Low.
Channel B Transmitter Serial Data Output: The least significant bit is transmitted first. This output is held in the
‘mark’ condition when the transmitter is disabled, idle, or when operating in local loop back mode. ‘Mark’ is High;
‘space’ is Low.
General–purpose input and output ports channel A: The character of these pins is controlled by I/OPCR. They may
be inputs or outputs and will present many internal clocks and interrupt signals: RTS, CTS, DTR, DSR etc. All have
change of state detectors and the input is always active. These pins are set to input only when addressed from the
low order 16 address space. When these pins are configured for interrupt type signals (RxRDY, TxRDY, C/TRDY)
They switch to open drain outputs.
General–purpose input and output ports channel B: The character of these pins is controlled by I/OPCR. They may
be inputs or outputs and will present many internal clocks and interrupt signals: RTS, CTS, DTR, DSR etc. All have
change of state detectors and the input is always active. These pins are set to output only when addressed from the
low order 16 address space. When these pins are configured for interrupt type signals (RxRDY, TxRDY, C/TRDY)
They switch to open drain outputs.
Power Supply: +3.3 or +5V supply input
parameters are specified with respect to the Vcc being at 3.3 of 5.0 volts +/– 10%
Ground (5 pins)
10% (4 pins). Operation is assured from 2.97 to 5.5 volts. Timing
3
(PRELIMINARY 2/10/00)
Objective specification
SC28L202