UM10413
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User manual
Rev. 1 — 16 December 2011
170 of 268
NXP Semiconductors
UM10413
MPT612 User manual
18.4.4 SSP Status register (SSPSR - 0xE006 800C)
This read-only register reflects the status of the SSP controller.
18.4.5 SSP Clock prescale register (SSPCPSR - 0xE006 8010)
This register controls the factor by which the prescaler divides the APB clock PCLK to
yield the prescaler clock that is, in turn, divided by the SCR factor in SSPCR0, to
determine the bit clock.
Remark:
the SSPCPSR value must be properly initialized or the SSP controller is not able
to transmit data correctly. If SSP is operating in master mode, CPSDVSR
min
= 2, while in
slave mode, CPSDVSR
min
= 12.
Table 151: SSP Data register (SSPDR - address 0xE006 8008) bit description
Bit
Symbol
Description
Reset value
15:0
DATA
write:
software can write data to be sent in a future frame to this
register whenever bit TNF in the status register is logic 1,
indicating that Tx FIFO is not full. If Tx FIFO was previously
empty and SSP controller is not busy on the bus, transmission of
data begins immediately. Otherwise data written to this register is
sent when all previous data has been sent (and received). If data
length is less than 16 bits, software must right-justify data written
to this register.
Read:
software can read data from this register whenever bit
RNE in the status register is logic 1, indicating that Rx FIFO is
not empty. When software reads this register, SSP controller
returns data from least recent frame in Rx FIFO. If data length is
less than 16 bits, data is right-justified in this field with
higher-order bits filled with logic 0s.
0x0000
Table 152: SSP Status register (SSPDR - address 0xE006 800C) bit description
Bit
Symbol
Description
Reset value
0
TFE
transmit FIFO empty. Logic 1 if transmit FIFO is empty, logic 0 if
not.
1
1
TNF
transmit FIFO not full. Logic 0 if Tx FIFO is full, logic 1 if not.
1
2
RNE
receive FIFO not empty. Logic 0 if receive FIFO is empty, logic 1
if not.
0
3
RFF
receive FIFO full. Logic 1 if receive FIFO is full, logic 0 if not.
0
4
BSY
busy. Logic 0 if SSP controller is idle, or logic 1 if currently
sending/receiving a frame and/or Tx FIFO is not empty.
0
7:5
-
reserved, user software must not write logic 1s to reserved bits;
value read from a reserved bit is not defined
n/a
Table 153: SSP Clock prescale register (SSPCPSR - address 0xE006 8010) bit description
Bit
Symbol
Description
Reset value
7:0
CPSDVSR even value between 2 and 254 by which PCLK is divided to
yield the prescaler output clock. Bit 0 always reads 0.
0