Motorola DSP56012 User Manual page 54

24-bit digital signal processor
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Signal Descriptions
Serial Host Interface (SHI)
Table 2-7 Serial Host Interface (SHI) Signals (Continued)
Signal
Signal
Name
Type
MISO/
Input or
SDA
Output
MOSI/
Input or
HA0
Output
2-14
State
during
Reset
Tri-stated
SPI Master-In-Slave-Out/I
Acknowledge—When the SPI is configured as a master,
MISO is the master data input line. The MISO signal is used
in conjunction with the MOSI signal for transmitting and
receiving serial data. This signal is a Schmitt-trigger input
when configured for the SPI Master mode, an output when
configured for the SPI Slave mode, and tri-stated if
configured for the SPI Slave mode when SS is deasserted.
2
In I
C mode, SDA is a Schmitt-trigger input when receiving
and an open-drain output when transmitting. SDA should be
connected to V
2
data for I
C transactions. The data in SDA must be stable
during the high period of SCL. The data in SDA is only
allowed to change when SCL is low. When the bus is free,
SDA is high. The SDA line is only allowed to change during
the time SCL is high in the case of start and stop events. A
high to low transition of the SDA line while SCL is high is an
unique situation, which is defined as the start event. A low to
high transition of SDA while SCL is high is an unique
situation, which is defined as the stop event.
An external pull-up resistor is not required.
Tri-stated
SPI Master-Out-Slave-In/I2C Slave Address 0—When the
SPI is configured as a master, MOSI is the master data output
line. The MOSI signal is used in conjunction with the MISO
signal for transmitting and receiving serial data. MOSI is the
slave data input line when the SPI is configured as a slave.
This signal is a Schmitt-trigger input when configured for the
SPI Slave mode.
This signal uses a Schmitt-trigger input when configured for
2
the I
C mode. When configured for I
signal is used to form the slave device address. HA0 is
ignored when it is configured for the I
An external pull-up resistor is not required.
DSP56012 User's Manual
Signal Description
2
C Data and
through a pull-up resistor. SDA carries the
CC
2
C Slave mode, the HA0
2
C Master mode.
MOTOROLA

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