ATmega1280 Atmel Corporation, ATmega1280 Datasheet - Page 252

• Manufacturer Part Number: ATmega1280
• Manufacturer: Atmel Corporation

Specifications of ATmega1280

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 86
• Ext Interrupts: 32
• Usb Speed: No
• Usb Interface: No
• Spi: 5
• Twi (i2c): 1
• Uart: 4
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 6
• Output Compare Channels: 16
• Input Capture Channels: 4
• Pwm Channels: 15
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

24.7
2549N–AVR–05/11
6
7
wait3:
in
sbrs r16,TWINT
rjmp wait3
in
andi r16, 0xF8
cpi
brne ERROR
ldi
out
Transmission Modes
Assembly Code Example
r16,TWCR
r16,TWSR
r16, MT_DATA_ACK
r16, (1<<TWINT)|(1<<TWEN)|
(1<<TWSTO)
TWCR, r16
The TWI can operate in one of four major modes. These are named Master Transmitter (MT),
Master Receiver (MR), Slave Transmitter (ST) and Slave Receiver (SR). Several of these
modes can be used in the same application. As an example, the TWI can use MT mode to write
data into a TWI EEPROM, MR mode to read the data back from the EEPROM. If other masters
are present in the system, some of these might transmit data to the TWI, and then SR mode
would be used. It is the application software that decides which modes are legal.
The following sections describe each of these modes. Possible status codes are described
along with figures detailing data transmission in each of the modes. These figures contain the
following abbreviations:
S:
Rs:
R:
W:
A:
A:
Data: 8-bit data byte
P:
SLA: Slave Address
In
TWINT Flag is set. The numbers in the circles show the status code held in TWSR, with the
prescaler bits masked to zero. At these points, actions must be taken by the application to con-
tinue or complete the TWI transfer. The TWI transfer is suspended until the TWINT Flag is
cleared by software.
When the TWINT Flag is set, the status code in TWSR is used to determine the appropriate soft-
ware action. For each status code, the required software action and details of the following serial
transfer are given in
bits are masked to zero in these tables.
Figure 24-12 on page 255
START condition
REPEATED START condition
Read bit (high level at SDA)
Write bit (low level at SDA)
Acknowledge bit (low level at SDA)
Not acknowledge bit (high level at SDA)
STOP condition
Table 24-2 on page 254
while (!(TWCR & (1<<TWINT)))
if ((TWSR & 0xF8) !=
MT_DATA_ACK)
TWCR = (1<<TWINT)|(1<<TWEN)|
(1<<TWSTO);
to
;
ERROR();
ATmega640/1280/1281/2560/2561
Figure 24-18 on page
C Example
to
Table 24-5 on page
264, circles are used to indicate that the
indicates that the DATA has been
transmitted, and ACK/NACK has
Register. Mask prescaler bits. If
MT_DATA_ACK go to ERROR
Wait for TWINT Flag set. This
Check value of TWI Status
263. Note that the prescaler
Transmit STOP condition
status different from
been received.
Comments
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