© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
191
Philips Semiconductors
UM10139
Volume 1
Chapter 13: SSP
13.4.3 SSP Data Register (SSPDR - 0xE006 8008)
Software can write data to be transmitted to this register, and read data that has been
received.
13.4.4 SSP
Status
Register (SSPSR - 0xE006 800C)
This read-only register reflects the current status of the SSP controller.
13.4.5 SSP
Clock
Prescale
Register (SSPCPSR - 0xE006 8010)
This register controls the factor by which the Prescaler divides the VPB clock PCLK to
yield the prescaler clock that is, in turn, divided by the SCR factor in SSPCR0, to
determine the bit clock.
Table 165: 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 the TNF bit in the Status register is 1,
indicating that the Tx FIFO is not full. If the Tx FIFO was
previously empty and the SSP controller is not busy on the bus,
transmission of the data will begin immediately. Otherwise the
data written to this register will be sent as soon as all previous
data has been sent (and received). If the data length is less than
16 bits, software must right-justify the data written to this register.
Read: software can read data from this register whenever the
RNE bit in the Status register is 1, indicating that the Rx FIFO is
not empty. When software reads this register, the SSP controller
returns data from the least recent frame in the Rx FIFO. If the
data length is less than 16 bits, the data is right-justified in this
field with higher order bits filled with 0s.
0x0000
Table 166: SSP Status Register (SSPDR - address 0xE006 800C) 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 SSP controller is idle, or 1 if it is
currently sending/receiving a frame and/or the Tx FIFO is not
empty.
0
7:5
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA
Table 167: SSP Clock Prescale Register (SSPCPSR - address 0xE006 8010) 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