AT89LP6440 datasheet(102/194 Pages) ATMEL

102 / 194 page

102

3706A–MICRO–9/09

AT89LP6440 - Preliminary

Notes:1. Set up the clock mode before enabling the SPI: set all bits needed in SPCR except the SPE bit, then set SPE.

2. Enable the master SPI prior to the slave device.

3. Slave echoes master on the next Tx if not loaded with new data.

SPR0

SPR1

SPI clock rate select. These two bits control the SCK rate of the device configured as master. SPR1 and SPR0 have no

effect on the slave. The relationship between SCK and the oscillator frequency, F

OSC., is as follows:

SPR1

SPR0

SCK (TSCK = 0)

SCK (TSCK = 1)

OSC/4

T1OVF/4

OSC/8

fT1OVF/8

OSC/32

fT1OVF/32

OSC/64

T1OVF/64

Symbol

Function

Table 17-3.

SPDR – SPI Data Register

SPDR Address = EAH

Reset Value= 00H (after cold reset)

unchanged (after warm reset)

Not Bit Addressable

SPD7

SPD6

SPD5

SPD4

SPD3

SPD2

SPD1

SPD0

Bit

76543210

Table 17-4.

SPSR – SPI Status Register

SPSR Address = E8H

Reset Value = 0000 X000B

Not Bit Addressable

SPIF

WCOL

MODF

TXE

–

SSIG

DISSOENH

Bit

76543

210

Symbol

Function

SPIF

SPI Transfer Complete Interrupt Flag. When a serial transfer is complete, the SPIF bit is set by hardware and an interrupt

is generated if ESP = 1. The SPIF bit may be cleared by software or by reading the SPI status register followed by

reading/writing the SPI data register.

WCOL

Write Collision Flag. The WCOL bit is set by hardware if SPDR is written while the transmit buffer is full. The ongoing

transfer is not affected. WCOL may be cleared by software or by reading the SPI status register followed by

reading/writing the SPI data register.

MODF

Mode Fault Flag. MODF is set by hardware when a master mode collision is detected (MSTR = 1, SSIG = 0 and SS = 0)

and an interrupt is generated if ESP= 1. MODF must be cleared by software.

TXE

Transmit Buffer Empty Flag. Set by hardware when the transmit buffer is loaded into the shift register, allowing a new byte

to be loaded. TXE must be cleared by software. When ENH = 1 and ESP = 1, TXE will generate an interrupt.

AT89LP6440 Datasheet(PDF) 102 Page - ATMEL Corporation

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