DS89C430_07 Datasheet, PDF (12/46 Pages) Dallas Semiconductor – Ultra-High-Speed Flash Microcontrollers

DS89C430/DS89C450 Ultra-High-Speed Flash Microcontrollers
PIN DESCRIPTION
PDIP
PIN
PLCC
TQFP
40
12, 44
6, 38
20
1, 22, 23, 16, 17, 28,
34
39
9
10
4
19
21
15
18
20
14
29
32
26
30
33
27
39
43
37
38
42
36
37
41
35
36
40
34
35
39
33
34
38
32
33
37
31
32
36
30
NAME
FUNCTION
V_CC
+5V
GND
RST
XTAL1
XTAL2
PSEN
ALE/PROG
P0.0 (AD0)
P0.1 (AD1)
P0.2 (AD2)
P0.3 (AD3)
P0.4 (AD4)
P0.5 (AD5)
P0.6 (AD6)
P0.7 (AD7)
Logic Ground
External Reset. The RST input pin is bidirectional and contains a Schmitt Trigger to
recognize external active-high reset inputs. The pin also employs an internal pulldown
resistor to allow for a combination of wire-ORed external reset sources. An RC is not
required for power-up, as the device provides this function internally.
Crystal Oscillators. These pins provide support for fundamental-mode parallel-resonant
AT-cut crystals. XTAL1 also acts as an input if there is an external clock source in place of
a crystal. XTAL2 serves as the output of the crystal amplifier.
Program Store Enable. This signal is commonly connected to optional external program
memory as a chip enable. PSEN provides an active-low pulse and is driven high when
external program memory is not being accessed. In one-cycle page mode 1, PSEN
remains low for consecutive page hits.
Address Latch Enable. This signal functions as a clock to latch the external address LSB
from the multiplexed address/data bus on Port 0. This signal is commonly connected to the
latch enable of an external 373-family transparent latch. In default mode, ALE has a pulse
width of 1.5 XTAL1 cycles and a period of four XTAL1 cycles. In page mode, the ALE
pulse width is altered according to the page mode selection. In traditional 8051 mode, ALE
is high when using the EMI reduction mode and during a reset condition. ALE can be
enabled by writing ALEON = 1 (PMR.2). Note that ALE operates independently of ALEON
during external memory accesses. As an alternate mode, this pin (PROG) is used to
execute the parallel program function.
Port 0 (AD0–AD7), I/O. Port 0 is an open-drain, 8-bit, bidirectional I/O port. As an
alternate function, Port 0 can function as the multiplexed address/data bus to access off-
chip memory. During the time when ALE is high, the LSB of a memory address is
presented. When ALE falls to logic 0, the port transitions to a bidirectional data bus. This
bus is used to read external program memory and read/write external RAM or peripherals.
When used as a memory bus, the port provides weak pullups for logic 1 outputs. The reset
condition of port 0 is tri-state. Pullup resistors are required only when using port 0 as an
I/O port.
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