________________________________________________ DS33X162/X161/X82/X81/X42/X41/X11/W41/W11
Rev: 063008
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8.1
Parallel Processor Interface
Configuration and control can be accomplished through the 8-bit parallel microprocessor port. The device’s 16-bit
registers are accessed as sequential byte addresses. The 8-bit parallel data bus can be configured for Intel or
Motorola modes of operation. The 8-bit parallel data bus can be configured for Intel or Motorola modes of operation
is mapped through the use of 11 address lines, A0-A10. An address latch enable [ALE] pin is provided to allow for
multiplexing of the data and address signals. Note that the parallel bus is not available in the 144 pin DS33X11,
and the SPI Slave port must be used for processor control.
The Chip Select (CS) pin must be brought to a logic low level to gain read and write access to the microprocessor
port. With Intel timing selected, the Read (RD) and Write (WR) pins are used to indicate read and write operations
and latch data through the interface. With Motorola timing selected, the Read-Write (RW) pin is used to indicate
read and write operations while the Data Strobe (DS) pin is used to latch data through the interface.
The interrupt output pin (INT) is an open-drain output that will assert a logic-low level upon a number of software
maskable interrupt conditions. The inactive state of this pin can be configured with the GL.CR2.INTM bit. This pin is
normally connected to the microprocessor interrupt input. The register map is shown in
Table 10-1 on Page
105.8.1.1 Read-Write/Data Strobe Modes
The processor interface can operate in either read-write strobe mode or data strobe mode. When MODE = 0 the
read-write strobe mode is enabled and a negative pulse on RD performs a read cycle, and a negative pulse on WR
performs a write cycle. When MODE pin = 1, the data strobe mode is enabled and a negative pulse on DS when
R
W is high performs a read cycle, and a negative pulse on DS when RW is low performs a write cycle. The read-
write strobe mode is commonly called the “Intel” mode, and the data strobe mode is commonly called the
“Motorola” mode.
8.1.2 Clear on Read
The latched status registers will clear on a read access. It is important to note that in a multi-task software
environment, the user should handle all status conditions of each register at the same time to avoid inadvertently
clearing status conditions. The latched status register bits are carefully designed so that an event occurrence
cannot collide with a user read access.
8.1.3 Interrupt and Pin Modes
The interrupt (INT) pin is configurable to drive high or float when not active. The GL.CR2.INTM bit controls the pin
configuration, when it is set to 1, the INT pin will drive high when inactive. After reset, the INT pin is in high
impedance mode until an interrupt source is active and enabled to drive the interrupt pin.
8.1.4 Multiplexed Bus Operation
An address latch enable [ALE] pin is provided to allow for multiplexing of the data and address signals. For
multiplexed operation, each of the eight data lines (D0-D7) must be externally connected to each of the lower eight
address lines (A0-A7). The remaining address lines (A8-A10) are connected as normal. Address inputs are latched
upon the falling edge of the ALE signal. ALE must remain low until the read or write operation is complete.