Freescale Semiconductor DSP56366 - Manual (Page 47)

Serial Host Interface
DSP56366 24-Bit Digital Signal Processor User Manual, Rev. 4
Freescale Semiconductor 2-13
MISO Input or output Tri-stated SPI Master-In-Slave-Out — 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. An external pull-up resistor is not required for SPI
operation.
SDA Input or
open-drain
output
I
2
C Data and Acknowledge — In I
2
C mode, SDA is a Schmitt-trigger input
when receiving and an open-drain output when transmitting. SDA should be
connected to V
CC
through a pull-up resistor. SDA carries the data for I 2 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 a unique situation, and is defined as the start event. A
low-to-high transition of SDA while SCL is high is a unique situation defined as
the stop event.
This signal is tri-stated during hardware, software, and individual reset. Thus,
there is no need for an external pull-up in this state.
This input is 5 V tolerant.
MOSI Input or output Tri-stated SPI Master-Out-Slave-In — 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.
HA0 Input I
2
C Slave Address 0 — This signal uses a Schmitt-trigger input when
configured for the I
2
C mode. When configured for I
2
C slave mode, the HA0
signal is used to form the slave device address. HA0 is ignored when configured
for the I
2 C master mode.
This signal is tri-stated during hardware, software, and individual reset. Thus,
there is no need for an external pull-up in this state.
This input is 5 V tolerant.
Table 2-10 Serial Host Interface Signals (continued)
Signal
Name
Signal Type
State during
Reset
Signal Description