Z86C21 Datasheet, PDF (11/35 Pages) Zilog, Inc. – 8K ROM Z8 CMOS MICROCONTROLLER

Table 4. Port 3 Pin Assignments
Pin
I/O
CTC1
Int.
P0 HS
P1 HS
P30
IN
P31
IN
P32
IN
P33
IN
IRQ3
T_IN
IRQ2
IRQ0
D/R
IRQ1
D/R
P34
OUT
P35
OUT
P36
OUT
T
OUT
R/D
R/D
P37
OUT
T0
T1
IRQ4
IRQ5
Notes:
HS = Handshake Signals; D = Data Available; R = Ready
Z86C21 MCU
WITH 8K ROM
P2 HS
D/R
UART
Ext
Serial In
DM
R/D
Serial Out
Auto Latch. The Auto Latch puts valid CMOS levels on all
CMOS inputs that are not externally driven. This reduces
excessive supply current flow in the input buffer when it is
not been driven by any source.
Low EMI Option. The Z86C21 is available in a Low EMI
option. This option is mask-programmable, to be selected
by the customer at the time when the ROM code is
submitted. Use of this feature results in:
s The pre-drivers slew rate reduced to 10 ns typical.
s Low EMI output drivers have resistance of 200 Ohms
typical.
s Oscillator divide-by-two circuitry is eliminated.
s Internal SCLK/TCLK operation is limited to a maximum
of 4 MHz (250 ns cycle time)
Transmitted Data (No Parity)
SP SP D7 D6 D5 D4 D3 D2 D1 D0 ST
Start Bit
Eight Data Bits
Two Stop Bits
Received Data (No Parity)
SP D7 D6 D5 D4 D3 D2 D1 D0 ST
Start Bit
Eight Data Bits
One Stop Bit
Transmitted Data (With Parity)
SP SP P D6 D5 D4 D3 D2 D1 D0 ST
Start Bit
Seven Data Bits
Odd Parity
Two Stop Bits
Received Data (With Parity)
SP P D6 D5 D4 D3 D2 D1 D0 ST
Start Bit
Seven Data Bits
Parity Error Flag
One Stop Bit
Figure 9. Serial Data Formats
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