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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
1178 of 1441
NXP Semiconductors
UM10503
Chapter 42: LPC43xx/LPC43Sxx SSP0/1
42.6.4 SSP Status Register
This read-only register reflects the current status of the SSP controller.
42.6.5 SSP Clock Prescale Register
This register controls the factor by which the Prescaler divides the SSP peripheral clock
PCLK to yield the prescaler clock that is, in turn, divided by the SCR factor in SSPnCR0,
to determine the bit clock.
Important:
the SSPnCPSR value must be properly initialized or the SSP controller will not
be able to transmit data correctly.
In Slave mode, the SSP clock rate provided by the master must not exceed 1/12 of the
SSP peripheral clock. The content of the SSPnCPSR register is not relevant.
In master mode, CPSDVSR
min
= 2 or larger (even numbers only).
42.6.6 SSP Interrupt Mask Set/Clear Register
This register controls whether each of the four possible interrupt conditions in the SSP
controller are enabled. Note that ARM uses the word “masked” in the opposite sense from
classic computer terminology, in which “masked” meant “disabled”. ARM uses the word
“masked” to mean “enabled”. To avoid confusion we will not use the word “masked”.
Table 979: SSP Status Register (SR - address 0x4008 300C (SSP0), 0x400C 500C (SSP1)) bit
description
Bit
Symbol Description
Reset
value
0
TFE
Transmit FIFO Empty. This bit is 1 is the Transmit FIFO is empty, 0 if not. 1
1
TNF
Transmit FIFO Not Full. This bit is 0 if the Tx FIFO is full, 1 if not.
1
2
RNE
Receive FIFO Not Empty. This bit is 0 if the Receive FIFO is empty, 1 if
not.
0
3
RFF
Receive FIFO Full. This bit is 1 if the Receive FIFO is full, 0 if not.
0
4
BSY
Busy. This bit is 0 if the SSPn controller is idle, or 1 if it is currently
sending/receiving a frame and/or the Tx FIFO is not empty.
0
31:5
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA
Table 980: SSP Clock Prescale Register (CPSR - address 0x4008 3010 (SSP0), 0x400C 5010
(SSP1)) bit description
Bit
Symbol
Description
Reset
value
7:0
CPSDVSR
This even value between 2 and 254, by which PCLK is divided to yield
the prescaler output clock. Bit 0 always reads as 0.
0
31:8
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA