ATMEGA64M1-15MZ Atmel, ATMEGA64M1-15MZ Datasheet - Page 163

• Manufacturer Part Number: ATMEGA64M1-15MZ
• Description: MCU AVR 64KB FLASH 3PSC 32-VQFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA64M1-15MZ

• Package / Case: 32-VQFN
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Eeprom Size: 2K x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Program Memory Size: 64KB (64K x 8)
• Data Converters: A/D 11x10b; D/A 1x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Connectivity: CAN, LIN, SPI, UART/USART
• Core Size: 8-Bit
• Processor Series: ATMEGA64x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, ATADAPCAN01
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Lead Free Status / Rohs Status: Details

15.2
15.2.1
15.2.2
15.2.3
7647G–AVR–09/11
SS Pin Functionality
Slave Mode
Master Mode
MCU Control Register – MCUCR
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– SPIPS: SPI Pin Redirection
Thanks to SPIPS (SPI Pin Select) in MCUCR Sfr, SPI pins can be redirected.
Note that programming port are always located on alternate SPI port.
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
• When the SPIPS bit is written to zero, the SPI signals are directed on pins MISO,MOSI,
• When the SPIPS bit is written to one,the SPI signals are directed on alternate SPI pins,
SCK and SS.
MISO_A, MOSI_A, SCK_A and SS_A.
of the SPI becoming a Slave, the MOSI and SCK pins become inputs.
SREG is set, the interrupt routine will be executed.
SPIPS
R/W
7
0
6
–
R
0
R
5
–
0
Atmel ATmega16/32/64/M1/C1
PUD
R/W
4
0
R
3
–
0
R
2
–
0
IVSEL
R/W
1
0
IVCE
R/W
0
0
MCUCR
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