UM10503
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User manual
Rev. 1.3 — 6 July 2012
1024 of 1269
NXP Semiconductors
UM10503
Chapter 40: LPC43xx SPI
40.7 Functional description
40.7.1 SPI data transfers
is a timing diagram that illustrates the four different data transfer formats that
are available with the SPI port. This timing diagram illustrates a single 8-bit data transfer.
The first thing you should notice in this timing diagram is that it is divided into three
horizontal parts. The first part describes the SCK and SSEL signals. The second part
describes the MOSI and MISO signals when the Clock Phase control bit (CPHA) in the
SPI Control Register is 0. The third part describes the MOSI and MISO signals when the
CPHA variable is 1.
In the first part of the timing diagram, note two points. First, the SPI is illustrated with the
Clock Polarity control bit (CPOL) in the SPI Control Register set to both 0 and 1. The
second point to note is the activation and de-activation of the SSEL signal. When
CPHA = 0, the SSEL signal will always go inactive between data transfers. This is not
guaranteed when CPHA = 1 (the signal can remain active).
Table 892: SPI Interrupt Register (INT - address 0x4010 001C) bit description
Bit
Symbol
Description
Reset
value
0
SPIF
SPI interrupt flag. Set by the SPI interface to generate an interrupt.
Cleared by writing a 1 to this bit.
Note:
this bit will be set once when SPIE = 1 and at least one of SPIF
and WCOL bits is 1. However, only when the SPI Interrupt bit is set and
SPI0 Interrupt is enabled in the NVIC, SPI based interrupt can be
processed by interrupt handling software.
0
7:1
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA
31:8
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA