dsp56004 Freescale Semiconductor, Inc, dsp56004 Datasheet - Page 16

• Manufacturer Part Number: dsp56004
• Description: Symphonytm Audio Dsp Family 24-bit Digital Signal Processors
• Manufacturer: Freescale Semiconductor, Inc

Signal/Connection Descriptions
Serial Host Interface (SHI)
SERIAL HOST INTERFACE (SHI)
1-10
SCK
SCL
Signal Name
The Serial Host Interface (SHI) has five I/O signals, which may be configured to
operate in either SPI or I
Input or
Input or
Output
Output
Signal
Type
Table 1-8 Serial Host Interface (SHI) signals
Freescale Semiconductor, Inc.
Tri-stated
For More Information On This Product,
during
Reset
State
2
C mode. Table 1-8 lists the SHI signals.
DSP56004/D, Rev. 3
Go to: www.freescale.com
SPI Serial Clock (SCK)—The SCK signal is an output
when the SPI is configured as a master, and a Schmitt-
trigger input when the SPI is configured as a slave. When
the SPI is configured as a master, the SCK signal is
derived from the internal SHI clock generator. When the
SPI is configured as a slave, the SCK signal is an input,
and the clock signal from the external master
synchronizes the data transfer. The SCK signal is ignored
by the SPI if it is defined as a slave and the Slave Select
(SS) signal is not asserted. In both the master and slave
SPI devices, data is shifted on one edge of the SCK signal
and is sampled on the opposite edge where data is stable.
Edge polarity is determined by the SPI transfer protocol.
I
transactions in the I
input when configured as a slave, and an open-drain
output when configured as a master. SCL should be
connected to V
maximum allowed internally generated bit clock
frequency is
I
maximum allowed externally generated bit clock
frequency is
I
software reset, or individual reset (no need for external
pull-up in this state).
2
2
2
C mode where F
C mode. This signal is tri-stated during hardware reset,
C Serial Clock (SCL)—SCL carries the clock for bus
Fosc
Fosc
CC
/
/
4
3
through a pull-up resistor. The
osc
Signal Description
for the SPI mode and
for the SPI mode and
2
C mode. SCL is a Schmitt-trigger
is the clock on EXTAL. The
Fosc
Fosc
MOTOROLA
/
/
6
5
for the
for the