UM10413
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User manual
Rev. 1 — 16 December 2011
160 of 268
NXP Semiconductors
UM10413
MPT612 User manual
18.3 Bus
description
18.3.1 Texas Instruments Synchronous Serial (SSI) frame format
shows the 4-wire Texas Instruments synchronous serial frame format supported
by the SSP module.
SSEL1
I/O
SSEL
FS
CS
Slave Select/Frame Sync/Chip Select.
If the SSP is a bus
master, it drives this signal shortly before the start of serial
data to shortly after the end of serial data, to signify a data
transfer as appropriate for the selected bus and mode.
When the SSP is a bus slave, this signal qualifies the
presence of data from the master according to the protocol
in use. When there is just one bus master and one bus
slave, the Frame Sync or Slave Select signal from the
master can be connected directly to the slave’s
corresponding input. If there is more than one slave on the
bus, further qualification of their Frame Select/Slave Select
inputs will typically be necessary to prevent more than one
slave from responding to a transfer.
MISO1
I/O
MISO
DR(M)
DX(S)
SI(M)
SO(S)
Master In Slave Out.
The MISO signal transfers serial data
from the slave to the master. When the SSP is a slave, serial
data is output on this signal. When the SSP is a master, it
clocks in serial data from this signal. If the SSP is a slave
and not selected by SSEL, it does not drive this signal
(leaves it in HIGH impedance state).
MOSI1
I/O
MOSI
DX(M)
DR(S)
SO(M)
SI(S)
Master Out Slave In.
The MOSI signal transfers serial data
from the master to the slave. When the SSP is a master, it
outputs serial data on this signal. When the SSP is a slave,
it clocks in serial data from this signal.
Table 147. SSP pin descriptions
…continued
Pin Name
Type
Interface pin name/function
Pin description
SPI
SSI
Microwire