ATMEGA16-16PU Atmel, ATMEGA16-16PU Datasheet - Page 138

• Manufacturer Part Number: ATMEGA16-16PU
• Description: IC AVR MCU 16K 16MHZ 5V 40DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA16-16PU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Package: 40PDIP
• Device Core: AVR
• Family Name: ATmega
• Maximum Speed: 16 MHz
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 32
• Interface Type: TWI/SPI/USART
• On-chip Adc: 8-chx10-bit
• Number Of Timers: 3
• Processor Series: ATMEGA16x
• Core: AVR8
• Data Ram Size: 1 KB
• Maximum Clock Frequency: 16 MHz
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• A/d Inputs: 8-Channel, 10-Bit
• Cpu Speed: 16 MIPS
• Eeprom Memory: 512 Bytes
• Input Output: 32
• Interface: JTAG/SPI/UART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 44-pin PDIP
• Programmable Memory: 16K Bytes
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 4.5-5.5 V
• Controller Family/series: AVR MEGA
• No. Of I/o's: 32
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 1KB
• Rohs Compliant: Yes
• For Use With: ATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFPATSTK600-DIP40 - STK600 SOCKET/ADAPTER 40-PDIP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRISP2 - PROGRAMMER AVR IN SYSTEMATJTAGICE2 - AVR ON-CHIP D-BUG SYSTEMATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

SS Pin Functionality
Slave Mode
Master Mode
SPI Control Register – SPCR
138
ATmega16(L)
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 syn-
chronous 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 following actions:
1. The MSTR bit in SPCR is cleared and the SPI system becomes a Slave. As a
2. The SPIF Flag in SPSR is set, and if the SPI interrupt is enabled, and the I-bit in
Thus, when interrupt-driven SPI transmission is used in Master mode, and there exists a
possibility 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 the 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
result 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
CPOL
R/W
3
0
CPHA
R/W
2
0
SPR1
R/W
1
0
SPR0
R/W
0
0
2466J–AVR–10/04
SPCR