UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
1022 of 1269
NXP Semiconductors
UM10503
Chapter 40: LPC43xx SPI
40.6.3 SPI Data Register
This bi-directional data register provides the transmit and receive data for the SPI.
Transmit data is provided to the SPI by writing to this register. Data received by the SPI
can be read from this register. When used as a master, a write to this register will start an
SPI data transfer. Writes to this register will be blocked when a data transfer starts, or
when the SPIF status bit is set, and the SPI Status Register has not been read.
40.6.4 SPI Clock Counter Register
This register controls the frequency of a master’s SCK. The register indicates the number
of SPI peripheral clock cycles that make up an SPI clock.
In Master mode, this register must be an even number greater than or equal to 8.
Violations of this can result in unpredictable behavior. The SPI SCK rate may be
calculated as: PCLK_SPI / SPCCR value.
In Slave mode, the SPI clock rate provided by the master must not exceed 1/8 of the SPI
peripheral clock. The content of the SPCCR register is not relevant.
6
WCOL
Write collision. When 1, this bit indicates that a write collision has
occurred. This bit is cleared by reading this register, then accessing the
SPI Data Register.
0
7
SPIF
SPI transfer complete flag. When 1, this bit indicates when a SPI data
transfer is complete. When a master, this bit is set at the end of the last
cycle of the transfer. When a slave, this bit is set on the last data
sampling edge of the SCK. This bit is cleared by first reading this
register, then accessing the SPI Data Register.
Note:
this is not the SPI interrupt flag. This flag is found in the SPINT
register.
0
31:8
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA
Table 887: SPI Status Register (SR - address 0x4010 0004) bit description
Bit
Symbol
Description
Reset
value
Table 888: SPI Data Register (DR - address 0x4010 0008) bit description
Bit
Symbol
Description
Reset
value
7:0
DATALOW
SPI Bi-directional data port.
0x00
15:8
DATAHIGH
If bit 2 of the SPCR is 1 and bits 11:8 are other than 1000, some or
all of these bits contain the additional transmit and receive bits.
When less than 16 bits are selected, the more significant among
these bits read as zeroes.
0x00
31:16 -
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA