ATA6617-P3QW Atmel, ATA6617-P3QW Datasheet - Page 169

• Manufacturer Part Number: ATA6617-P3QW
• Description: MCU W/LIN TX/5V REG/WTCDG 38VQFN
• Manufacturer: Atmel
• Series: AVR® ATA66 LIN-SBCr

Specifications of ATA6617-P3QW

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, LIN, SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 16
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 11x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 38-VQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.14.2
4.14.2.1
4.14.2.2
4.14.2.3
9132D–AUTO–12/10
SS Pin Functionality
Slave Mode
Master Mode
SPI Control Register – SPCR
When the SPI is configured as a Slave, the Slave Select (SS) pin is always input. When SS is
held low, the SPI is activated, and MISO becomes an output if configured so by the user. All
other pins are inputs. When SS is driven high, all pins are inputs, and the SPI is passive, which
means that it will not receive incoming data. Note that the SPI logic will be reset once the SS
pin is driven high.
The SS pin is useful for packet/byte synchronization to keep the slave bit counter synchronous
with the master clock generator. When the SS pin is driven high, the SPI slave will immediately
reset the send and receive logic, and drop any partially received data in the Shift Register.
When the SPI is configured as a Master (MSTR in SPCR is set), the user can determine the
direction of the SS pin.
If SS is configured as an output, the pin is a general output pin which does not affect the SPI
system. Typically, the pin will be driving the SS pin of the SPI Slave.
If SS is configured as an input, it must be held high to ensure Master SPI operation. If the SS
pin is driven low by peripheral circuitry when the SPI is configured as a Master with the SS pin
defined as an input, the SPI system interprets this as another master selecting the SPI as a
slave and starting to send data to it. To avoid bus contention, the SPI system takes the follow-
ing actions:
Thus, when interrupt-driven SPI transmission is used in Master mode, and there exists a pos-
sibility that SS is driven low, the interrupt should always check that the MSTR bit is still set. If
the MSTR bit has been cleared by a slave select, it must be set by the user to re-enable SPI
Master mode.
• Bit 7 – SPIE: SPI Interrupt Enable
This bit causes the SPI interrupt to be executed if SPIF bit in the SPSR Register is set and if
the Global Interrupt Enable bit in SREG is set.
• Bit 6 – SPE: SPI Enable
When the SPE bit is written to one, the SPI is enabled. This bit must be set to enable any SPI
operations.
• Bit 5 – DORD: Data Order
When the DORD bit is written to one, the LSB of the data word is transmitted first.
When the DORD bit is written to zero, the MSB of the data word is transmitted first.
Bit
Read/Write
Initial Value
1. The MSTR bit in SPCR is cleared and the SPI system becomes a Slave. As a result
2. The SPIF flag in SPSR is set, and if the SPI interrupt is enabled, and the I-bit in
of the SPI becoming a Slave, the MOSI and SCK pins become inputs.
SREG is set, the interrupt routine will be executed.
SPIE
R/W
7
0
SPE
R/W
6
0
DORD
R/W
5
0
MSTR
R/W
4
0
Atmel ATA6616/ATA6617
CPOL
R/W
3
0
CPHA
R/W
2
0
SPR1
R/W
1
0
SPR0
R/W
0
0
SPCR
169