DS5000FP Datasheet, PDF (4/22 Pages) Dallas Semiconductor – Soft Microprocessor Chip

DS5000FP
PIN DESCRIPTION
PIN
NAME
FUNCTION
15, 17, 19, 21,
25, 27, 29, 31
P1.0–P1.7 General-Purpose I/O Port 1
34
RST
Active-High Reset Input. A logic 1 applied to this pin activates a reset state. This
pin is pulled down internally so this pin can be left unconnected if not used.
36
P3.0/
RXD
General-Purpose I/O Port Pin 3.0. Also serves as the receive signal for the on
board UART. This pin should not be connected directly to a PC COM port.
38
P3.1/
TXD
General-Purpose I/O Port Pin 3.1. Also serves as the transmit signal for the on-
board UART. This pin should not be connected directly to a PC COM port.
39
P3.2/
INT0
General-Purpose I/O Port Pin 3.2. Also serves as the active-low External
Interrupt 0.
40
P3.3/
INT1
General-Purpose I/O Port Pin 3.3. Also serves as the active-low External
Interrupt 1.
41
P3.4/T0 General-Purpose I/O Port Pin 3.4. Also serves as the Timer 0 input.
44
P3.5/T1 General-Purpose I/O Port Pin 3.5. Also serves as the Timer 1 input.
45
General-Purpose I/O Port Pin. Also serves as the write strobe for expanded bus
P3.6/ WR _operation.
46
P3.7/ RD
General-Purpose I/O Port Pin. Also serves as the read strobe for expanded bus
operation.
47, 48
XTAL2, Crystal Connections. Used to connect an external crystal to the internal
XTAL1 oscillator. XTAL1 is the input to an inverting amplifier and XTAL2 is the output.
52, 53
GND Logic Ground
49, 50, 51, 56,
58, 60, 64, 66
P2.0–P2.7
General-Purpose I/O Port 2. Also serves as the MSB of the expanded address
bus.
Program Store Enable. This active-low signal is used to enable an external
program memory when using the expanded bus. It is normally an output and
should be unconnected if not used. PSEN is also used to invoke the Bootstrap
68
PSEN Loader. At this time, PSEN will be pulled down externally. This should only be
done once the DS5000FP is already in a reset state. The device that pulls down
should be open drain since it must not interfere with PSEN under normal
operation.
Address Latch Enable. Used to de-multiplex the multiplexed Expanded
Address/Data bus on Port 0. This pin is normally connected to the clock input on a
70
ALE _{’373 type transparent latch. When using a parallel programmer, this pin also}
assumes the PROG function for programming pulses.
External Access. This pin forces the DS5000FP to behave like an 8031. No
73
internal memory (or clock) will be available when this pin is at a logic low. Since
EA
this pin is pulled down internally, it should be connected to +5V to use NV RAM.
In a parallel programmer, this pin also serves as V_PP for super voltage pulses.
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