ATmega32 Atmel Corporation, ATmega32 Datasheet - Page 183

• Manufacturer Part Number: ATmega32
• Manufacturer: Atmel Corporation

Specifications of ATmega32

• Flash (kbytes): 32 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

Transmission
Modes
Master Transmitter
Mode
2503Q–AVR–02/11
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: START condition
Rs: REPEATED START condition
R: Read bit (high level at SDA)
W: Write bit (low level at SDA)
A: Acknowledge bit (low level at SDA)
A: Not acknowledge bit (high level at SDA)
Data: 8-bit data byte
P: STOP condition
SLA: Slave Address
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 continue 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
these tables.
In the Master Transmitter mode, a number of data bytes are transmitted to a slave receiver (see
Figure
of the following address packet determines whether Master Transmitter or Master Receiver
mode is to be entered. If SLA+W is transmitted, MT mode is entered, if SLA+R is transmitted,
MR mode is entered. All the status codes mentioned in this section assume that the prescaler
bits are zero or are masked to zero.
Figure 86. Data Transfer in Master Transmitter Mode
Figure 87
SDA
SCL
86). In order to enter a Master mode, a START condition must be transmitted. The format
to
Figure
TRANSMITTER
Device 1
MASTER
Table 74
93, circles are used to indicate that the TWINT Flag is set. The numbers in
Device 2
RECEIVER
to
SLAVE
Table
77. Note that the prescaler bits are masked to zero in
Device 3
........
Device n
V
CC
ATmega32(L)
R1
R2
183