ATTINY24A-SSU Atmel, ATTINY24A-SSU Datasheet - Page 121

• Manufacturer Part Number: ATTINY24A-SSU
• Description: MCU AVR 2K FLASH 20MHZ 14SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY24A-SSU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 12
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Processor Series: ATTINY2x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 128 B
• Interface Type: SPI, USI
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 12
• Number Of Timers: 2
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 20 Channel
• For Use With: ATSTK505 - ADAPTER KIT FOR 14PIN AVR MCU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8183C–AVR–03/11
Figure 14-4.
The data direction is not given by the physical layer. A protocol, like the one used by the TWI-
bus, must be implemented to control the data flow.
Figure 14-5.
Referring to the timing diagram
SDA
SCL
1. The start condition is generated by the master by forcing the SDA low line while keep-
2. In addition, the start detector will hold the SCL line low after the master has forced a
3. The master set the first bit to be transferred and releases the SCL line (C). The slave
ing the SCL line high (A). SDA can be forced low either by writing a zero to bit 7 of the
USI Data Register, or by setting the corresponding bit in the PORTA register to zero.
Note that the Data Direction Register bit must be set to one for the output to be
enabled. The start detector logic of the slave device (see
detects the start condition and sets the USISIF Flag. The flag can generate an interrupt
if necessary.
negative edge on this line (B). This allows the slave to wake up from sleep or complete
other tasks before setting up the USI Data Register to receive the address. This is done
by clearing the start condition flag and resetting the counter.
samples the data and shifts it into the USI Data Register at the positive edge of the SCL
clock.
SLAVE
MASTER
A B
S
Bit7
Bit7
Two-wire Mode Operation, Simplified Diagram
Two-wire Mode, Typical Timing Diagram
Bit6
Bit6
C
ADDRESS
1 - 7
Bit5
Bit5
Bit4
Bit4
Bit3
Bit3
R/W
(Figure
8
D
Bit2
Bit2
Bit1
Bit1
14-5), a bus transfer involves the following steps:
ACK
9
Bit0
Bit0
E
DATA
1 - 8
Two-wire Clock
Control Unit
ATtiny24A/44A/84A
ACK
9
PORTxn
Figure 14-6 on page
HOLD
SCL
DATA
1 - 8
SDA
SCL
SDA
SCL
ACK
9
VCC
122)
P
F
121