UL
®
LSI/CSI
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
f
CKO
f
CKi
Vss
SS/
SCK
MISO
MOSI
LS7366
(631) 271-0400 FAX (631) 271-0405
A3800
32-BIT QUADRATURE COUNTER WITH SERIAL INTERFACE
GENERAL FEATURES:
• Operating voltage: 3.0V to 5.5V (V
DD
- V
SS
)
• 5V count frequency: 40MHz
• 3V count frequency: 20MHz
• 32-bit counter (CNTR).
• 32-bit data register (DTR) and comparator.
• 32-bit output register (OTR).
• Two 8-bit mode registers (MDR0, MDR1) for programmable
functional modes.
• 8-bit instruction register (IR).
• 8-bit status register (STR).
• Latched Interrupt output on Carry or Borrow or Compare or Index.
• Index driven counter load, output register load or counter reset.
• Internal quadrature clock decoder and filter.
• x1, x2 or x4 mode of quadrature counting.
• Non-quadrature up/down counting.
• Modulo-N, Non-recycle, Range-limit or
Free-running modes of counting
• 8-bit, 16-bit, 24-bit and 32-bit programmable configuration
synchronous (SPI) serial interface
• LS7366 (DIP); LS7366-S (SOIC); LS7366-TS (TSSOP)
- See Figure 1-
SPI/MICROWIRE
(Serial Peripheral Interface):
• Standard 4-wire connection: MOSI, MISO, SS/ and SCK.
• Slave mode only.
GENERAL DESCRIPTION:
LS7366 is a 32-bit CMOS counter, with direct interface for quadra-
ture clocks from incremental encoders. It also interfaces with the
index signals from incremental encoders to perform variety of
marker functions.
For communications with microprocessors or microcontrollers, it
provides a 4-wire SPI/MICROWIRE bus.The four standard bus I/Os
are SS/, SCK, MISO and MOSI. The data transfer between a micro-
controller and a slave LS7366 is synchronous. The synchronization
is done by the SCK clocks supplied by the microcontroller.
Each transmission is organized in blocks of 1 to 5 bytes of data.
A transmission cycle is intitiated by a high to low transition of the
SS/ input. The first byte received in a transmission cycle is always
an instruction byte, whereas the second through the fifth bytes are
always interpreted as data bytes. A transmission cycle is terminated
with the low to high transition of the SS/ input. Received bytes are
shifted in at the MOSI input, MSB first, with the leading edges
(high transition) of the SCK clocks. Output data are shifted out on
the MISO output, MSB first, with the trailing edges (low transition)
of the SCK clocks.
7366-012605-1
January 2005
PIN ASSIGNMENT
TOP VIEW
14
13
12
LS7366
11
10
9
8
FIGURE 1
V
DD
CNT_EN
A
B
INDEX
DFLAG/
LFLAG/
1
2
3
4
5
6
7
Read and write commands cannot be combined.
For example, when the device is shifting out read
data on MISO output, it ignores the MOSI input,
even though the SS/ input is active. SS/ must be
terminated and reasserted before the device will
accept a new command.
The counter can be configured to operate as a
1, 2, 3 or 4-byte counter. When configured as a
n-byte counter, the CNTR, DTR and OTR are all
configured as n-byte registers, where n = 1, 2, 3 or
4. The content of the instruction/data identity is
automatically adjusted to match the n-byte configu-
ration. For example, if the counter is configured as a
2-byte counter, the instruction “write to DTR”
expects 2 data bytes following the instruction byte.
If the counter is configured as a 3-byte counter, the
same instruction will expect 3 bytes of data follow-
ing the instruction byte.
Following the transfer of the appropriate number of
bytes any further attempt of data transfer is ignored
until a new instruction cycle is started by switching
the SS/ input to high and then low.
The counter can be programmed to operate in a
number of different modes, with the operating
characteristics being written into the two mode
registers MDR0 and MDR1. Hardware I/Os are
provided for event driven operations, such as
processor interrupt and index related functions.
LSI [ LSI COMPUTER SYSTEMS ]
