UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
1019 of 1269
NXP Semiconductors
UM10503
Chapter 40: LPC43xx SPI
40.5 Pin description
40.6 Register description
The SPI contains registers as shown in
. All registers are byte, half word and
word accessible.
Table 884. SPI pin description
Pin
Name
Type
Pin Description
SCK
Input/
Output
Serial Clock.
The SPI clock signal (SCK) is 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.
SSEL
Input
Slave Select.
The SPI slave select signal (SSEL) 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.
Remark:
Note that this pin in an input pin only. The SPI in master mode cannot
drive the CS input on the slave. Any GPIO pin can be used for SPI chip select in
master mode.
MISO
Input/
Output
Master In Slave Out.
The SPI Master In Slave Out signal (MISO) is a
unidirectional signal used to transfer serial data from an SPI slave to an SPI
master. When a device is a slave, serial data is output on this pin. When a
device is a master, serial data is input on this pin. When a slave device is not
selected, the slave drives the signal high-impedance.
MOSI
Input/
Output
Master Out Slave In.
The SPI Master Out Slave In signal (MOSI) is a
unidirectional signal used to transfer serial data from an SPI master to an SPI
slave. When a device is a master, serial data is output on this pin. When a
device is a slave, serial data is input on this pin.
Table 885. Register overview: SPI (base address 0x4010 0000)
Name
Access
Address
offset
Description
Reset
value
CR
R/W
0x000
SPI Control Register. This register controls the
operation of the SPI.
0x00
SR
RO
0x004
SPI Status Register. This register shows the
status of the SPI.
0x00
DR
R/W
0x008
SPI Data Register. This bi-directional register
provides the transmit and receive data for the
SPI. Transmit data is provided to the SPI0 by
writing to this register. Data received by the SPI0
can be read from this register.
0x00
CCR
R/W
0x00C
SPI Clock Counter Register. This register
controls the frequency of a master’s SCK0.
0x00