User Manual

164
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
8271E–AVR–07/2012
When the SPI is enabled, the data direction of the MOSI, MISO, SCK, and SS pins is overridden according to
Table 19-1 on page 164. For more details on automatic port overrides, refer to ”Alternate Port Functions” on page
81.
Note: See ”Alternate Functions of Port B” on page 83 for a detailed description of how to define the direction of the user
defined SPI pins.
The following code examples show how to initialize the SPI as a Master and how to perform a simple transmission.
DDR_SPI in the examples must be replaced by the actual Data Direction Register controlling the SPI pins.
DD_MOSI, DD_MISO and DD_SCK must be replaced by the actual data direction bits for these pins. E.g. if MOSI
is placed on pin PB5, replace DD_MOSI with DDB5 and DDR_SPI with DDRB.
Table 19-1. SPI Pin Overrides
(Note:)
Pin Direction, Master SPI Direction, Slave SPI
MOSI User Defined Input
MISO Input User Defined
SCK User Defined Input
SS
User Defined Input