Z8F1601 Datasheet, PDF (122/246 Pages) Zilog, Inc. – Z8 Encore Microcontrollers with Flash Memory and 10-Bit A/D Converter

Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
Z8 Encore!^®
104
SCK
(CLKPOL = 0)
SCK
(CLKPOL = 1)
MOSI
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
MISO
Input Sample Time
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SS
Figure 78. SPI Timing When PHASE is 1
Multi-Master Operation
In a multi-master SPI system, all SCK pins are tied together, all MOSI pins are tied
together and all MISO pins are tied together. All SPI pins must then be configured in
open-drain mode to prevent bus contention. At any one time, only one SPI device is con-
figured as the Master and all other SPI devices on the bus are configured as Slaves. The
Master enables a single Slave by asserting the SS pin on that Slave only. Then, the single
Master drives data out its SCK and MOSI pins to the SCK and MOSI pins on the Slaves
(including those which are not enabled). The enabled Slave drives data out its MISO pin to
the MISO Master pin.
For a Master device operating in a multi-master system, if the SS pin is configured as an
input and is driven Low by another Master, the COL bit is set to 1 in the SPI Status Regis-
ter. The COL bit indicates the occurrence of a multi-master collision (mode fault error con-
dition).
PS017610-0404
Serial Peripheral Interface