ATMEGA16A-PU Atmel, ATMEGA16A-PU Datasheet - Page 199

MCU AVR 16K FLASH 16MHZ 40-PDIP

ATMEGA16A-PU

Manufacturer Part Number
ATMEGA16A-PU
Description
MCU AVR 16K FLASH 16MHZ 40-PDIP
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheets

Specifications of ATMEGA16A-PU

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)
2.7 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)
Processor Series
ATMEGA16x
Core
AVR8
Data Bus Width
8 bit
Data Ram Size
1 KB
Interface Type
2-Wire/SPI/USART
Maximum Clock Frequency
16 MHz
Number Of Programmable I/os
32
Number Of Timers
3
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
On-chip Adc
8-ch x 10-bit
Package
40PDIP
Device Core
AVR
Family Name
ATmega
Maximum Speed
16 MHz
Operating Supply Voltage
3.3|5 V
Controller Family/series
AVR MEGA
No. Of I/o's
32
Eeprom Memory Size
512Byte
Ram Memory Size
1KB
Cpu Speed
16MHz
Rohs Compliant
Yes
For Use With
ATSTK600 - DEV KIT FOR AVR/AVR32ATSTK500 - PROGRAMMER AVR STARTER KIT
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
20.8
8154B–AVR–07/09
Multi-master Systems and Arbitration
Note that data is transmitted both from Master to Slave and vice versa. The Master must instruct
the Slave what location it wants to read, requiring the use of the MT mode. Subsequently, data
must be read from the Slave, implying the use of the MR mode. Thus, the transfer direction must
be changed. The Master must keep control of the bus during all these steps, and the steps
should be carried out as an atomical operation. If this principle is violated in a multi-master sys-
tem, another Master can alter the data pointer in the EEPROM between steps 2 and 3, and the
Master will read the wrong data location. Such a change in transfer direction is accomplished by
transmitting a REPEATED START between the transmission of the address byte and reception
of the data. After a REPEATED START, the Master keeps ownership of the bus. The following
figure shows the flow in this transfer.
Figure 20-19. Combining Several TWI Modes to Access a Serial EEPROM
If multiple Masters are connected to the same bus, transmissions may be initiated simultane-
ously by one or more of them. The TWI standard ensures that such situations are handled in
such a way that one of the Masters will be allowed to proceed with the transfer, and that no data
will be lost in the process. An example of an arbitration situation is depicted below, where two
Masters are trying to transmit data to a Slave Receiver.
Figure 20-20. An Arbitration Example
Several different scenarios may arise during arbitration, as described below:
4. The transfer must be finished
• Two or more Masters are performing identical communication with the same Slave. In this
• Two or more Masters are accessing the same Slave with different data or direction bit. In this
case, neither the Slave nor any of the Masters will know about the bus contention.
case, arbitration will occur, either in the READ/WRITE bit or in the data bits. The Masters
trying to output a one on SDA while another Master outputs a zero will lose the arbitration.
S
S = START
SDA
SCL
Transmitted from Master to Slave
SLA+W
TRANSMITTER
Device 1
MASTER
A
Master Transmitter
TRANSMITTER
ADDRESS
Device 2
MASTER
Device 3
RECEIVER
A
SLAVE
Rs = REPEATED START
Rs
Transmitted from Slave to Master
........
SLA+R
Device n
A
V
CC
Master Receiver
ATmega16A
DATA
R1
P = STOP
R2
A
P
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