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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
388 of 808
NXP Semiconductors
UM10360
Chapter 18: LPC17xx SSP0/1 interface
The LPC17xx has two Synchronous Serial Port controllers -- SSP0 and SSP1.
4.
Pin descriptions
5.
Bus description
5.1 Texas Instruments synchronous serial frame format
shows the 4-wire Texas Instruments synchronous serial frame format
supported by the SSP module.
Table 348. SSP pin descriptions
Pin
Name
Type
Interface pin
name/function
Pin Description
SPI
SSI
Microwire
SCK0/1
I/O
SCK
CLK
SK
Serial Clock.
SCK/CLK/SK is a clock signal used
to synchronize the transfer of data. It is driven by
the master and received by the slave. When the
SPI interface is used, the clock is programmable to
be active-high or active-low, otherwise it is always
active-high. SCK1 only switches during a data
transfer. Any other time, the SSPn interface either
holds it in its inactive state, or does not drive it
(leaves it in high-impedance state).
SSEL0/1 I/O
SSEL FS
CS
Frame Sync/Slave Select.
When the SSPn
interface is a bus master, it drives this signal to an
active state before the start of serial data, and then
releases it to an inactive state after the serial data
has been sent. The active state of this signal can
be high or low depending upon the selected bus
and mode. When the SSPn 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. When 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.
MISO0/1 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
SSPn is a slave, serial data is output on this signal.
When the SSPn is a master, it clocks in serial data
from this signal. When the SSPn is a slave and is
not selected by FS/SSEL, it does not drive this
signal (leaves it in high-impedance state).
MOSI0/1 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
SSPn is a master, it outputs serial data on this
signal. When the SSPn is a slave, it clocks in serial
data from this signal.