AT90PWM2 datasheet(190/365 Pages) ATMEL

190 / 365 page

190

AT90PWM2/3

4317B–AVR–02/05

SPI Status Register – SPSR

• Bit 7 – SPIF: SPI Interrupt Flag

When a serial transfer is complete, the SPIF flag is set. An interrupt is generated if SPIE

in SPCR is set and global interrupts are enabled. If SS is an input and is driven low

when the SPI is in Master mode, this will also set the SPIF flag. SPIF is cleared by hard-

ware when executing the corresponding interrupt handling vector. Alternatively, the

SPIF bit is cleared by first reading the SPI Status Register with SPIF set, then accessing

the SPI Data Register (SPDR).

• Bit 6 – WCOL: Write COLlision Flag

The WCOL bit is set if the SPI Data Register (SPDR) is written during a data transfer.

The WCOL bit (and the SPIF bit) are cleared by first reading the SPI Status Register

with WCOL set, and then accessing the SPI Data Register.

• Bit 5..1 – Res: Reserved Bits

These bits are reserved bits in the AT90PWM2/3 and will always read as zero.

• Bit 0 – SPI2X: Double SPI Speed Bit

When this bit is written logic one the SPI speed (SCK Frequency) will be doubled when

the SPI is in Master mode (see Table 73). This means that the minimum SCK period will

be two CPU clock periods. When the SPI is configured as Slave, the SPI is only guaran-

teed to work at f

clkio/4 or lower.

The SPI interface on the AT90PWM2/3 is also used for program memory and EEPROM

downloading or uploading. See Serial Programming Algorithm305 for serial program-

ming and verification.

SPI Data Register – SPDR

• Bits 7:0 - SPD7:0: SPI Data

The SPI Data Register is a read/write register used for data transfer between the Regis-

ter File and the SPI Shift Register. Writing to the register initiates data transmission.

Reading the register causes the Shift Register Receive buffer to be read.

Bit

765

432

SPIF

WCOL

–

SPI2X

SPSR

Read/Write

RRR

R/W

Initial Value

000

Bit

765

432

SPD7

SPD6

SPD5

SPD4

SPD3

SPD2

SPD1

SPD0

SPDR

Read/Write

R/W

Initial Value

Undefined

AT90PWM2 Datasheet(PDF) 190 Page - ATMEL Corporation

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