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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
395 of 808
NXP Semiconductors
UM10360
Chapter 18: LPC17xx SSP0/1 interface
5.3.1 Setup and hold time requirements on CS with respect to SK in Microwire
mode
In the Microwire mode, the SSP slave samples the first bit of receive data on the rising
edge of SK after CS has gone LOW. Masters that drive a free-running SK must ensure
that the CS signal has sufficient setup and hold margins with respect to the rising edge of
SK.
illustrates these setup and hold time requirements. With respect to the SK
rising edge on which the first bit of receive data is to be sampled by the SSP slave, CS
must have a setup of at least two times the period of SK on which the SSP operates. With
respect to the SK rising edge previous to this edge, CS must have a hold of at least one
SK period.
6.
Register description
The register addresses of the SSP controllers addresses are shown in
Fig 80. Microwire frame format (continuos transfers)
SK
CS
SO
SI
MSB
LSB
4 to 16 bits
output data
8-bit control
4 to 16 bits
output data
MSB
LSB
0
MSB
LSB
LSB
Fig 81. Microwire frame format setup and hold details
SK
CS
SI
t
HOLD
= t
SK
t
SETUP
=2*t
SK
Table 349. SSP Register Map
Generic Name
Description
Access
Reset
Value
SSPn Register
Name & Address
CR0
Control Register 0. Selects the serial clock rate, bus
type, and data size.
R/W
0
SSP0CR0 - 0x4008 8000
SSP1CR0 - 0x4003 0000
CR1
Control Register 1. Selects master/slave and other
modes.
R/W
0
SSP0CR1 - 0x4008 8004
SSP1CR1 - 0x4003 0004
DR
Data Register. Writes fill the transmit FIFO, and
reads empty the receive FIFO.
R/W
0
SSP0DR - 0x4008 8008
SSP1DR - 0x4003 0008