Philips Semiconductors
P89LPC930/931
8-bit microcontrollers with two-clock 80C51 core
Product data Rev. 05 — 15 December 2004 32 of 55
9397 750 14472
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
The SPI interface has four pins: SPICLK, MOSI, MISO, and SS:
• SPICLK, MOSI and MISO are typically tied together between two or more SPI
devices. Data flows from master to slave on MOSI (Master Out Slave In) pin and
flows from slave to master on MISO (Master In Slave Out) pin. The SPICLK signal
is output in the master mode and is input in the slave mode. If the SPI system is
disabled, i.e. SPEN (SPCTL.6) = 0 (reset value), these pins are configured for port
functions.
• SS is the optional slave select pin. In a typical configuration, an SPI master asserts
one of its port pins to select one SPI device as the current slave. An SPI slave
device uses its SS pin to determine whether it is selected.
Typical connections are shown in Figures 10, 11, and 12.
Fig 9. SPI block diagram.
002aaa434
CPU clock
DIVIDER
BY 4, 16, 64, 128
SELECT
CLOCK LOGIC
SPI CONTROL REGISTER
READ DATA BUFFER
8-BIT SHIFT REGISTER
SPI CONTROL
SPI STATUS REGISTER
SPR1
SPIF
WCOL
SPR0
SPI clock (master)
PIN CONTROL LOGIC
S
M
S
M
M
S
MISO
P2.3
MOSI
P2.2
SPICLK
P2.5
SS
P2.4
SPI
interrupt
request
internal
data
bus
SSIG
SPEN
SPEN
MSTR
DORD
MSTR
CPHA
CPOL
SPR1
SPR0
MSTR
SPEN
clock
