Pin Description - Philips LPC2119 User Manual

Philips Semiconductors
ARM-based Microcontroller

PIN DESCRIPTION

Table 114: SPI Pin Description
Pin Name Type
Input/
SCK1, SCK0
Output
SSEL1, SSEL0 Input
Input/
MISO1, MISO0
Output
Input/
MOSI1, MOSI0
Output
SPI Interface
Serial Clock. The SPI is a clock signal used to synchronize the transfer of data across the SPI
interface. The SPI is always driven by the master and received by the slave. The clock is
programmable to be active high or active low. The SPI is only active during a data transfer. Any
other time, it is either in its inactive state, or tri-stated.
Slave Select. The SPI slave select signal is an active low signal that indicates which slave is
currently selected to participate in a data transfer. Each slave has its own unique slave select
signal input. The SSEL must be low before data transactions begin and normally stays low for
the duration of the transaction. If the SSEL signal goes high any time during a data transfer, the
transfer is considered to be aborted. In this event, the slave returns to idle, and any data that
was received is thrown away. There are no other indications of this exception. This signal is not
directly driven by the master. It could be driven by a simple general purpose I/O under software
control.
Note: LPC___ configured to operate as SPI master MUST select SSEL functionality on
an apropriate pin and have HIGH level on this pin in order to act as a master.
Master In Slave Out. The MISO signal is a unidirectional signal used to transfer serial data
from the slave to the master. When a device is a slave, serial data is output on this signal. When
a device is a master, serial data is input on this signal. When a slave device is not selected, the
slave drives the signal high impedance.
Master Out Slave In. The MOSI signal is a unidirectional signal used to transfer serial data
from the master to the slave. When a device is a master, serial data is output on this signal.
When a device is a slave, serial data is input on this signal.
LPC2119/2129/2292/2294
Pin Description
152
Preliminary User Manual
January 08, 2004