ATMEGA32A-MNR Atmel, ATMEGA32A-MNR Datasheet - Page 204

• Manufacturer Part Number: ATMEGA32A-MNR
• Description: IC MCU AVR 32K 16MHZ 44VQFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA32A-MNR

• 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: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K 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: 44-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

20.9.3
20.9.4
8155C–AVR–02/11
TWSR – TWI Status Register
TWDR – TWI Data Register
• Bit 2 – TWEN: TWI Enable Bit
The TWEN bit enables TWI operation and activates the TWI interface. When TWEN is written to
one, the TWI takes control over the I/O pins connected to the SCL and SDA pins, enabling the
slew-rate limiters and spike filters. If this bit is written to zero, the TWI is switched off and all TWI
transmissions are terminated, regardless of any ongoing operation.
• Bit 1 – Reserved Bit
This bit is a reserved bit and will always read as zero.
• Bit 0 – TWIE: TWI Interrupt Enable
When this bit is written to one, and the I-bit in SREG is set, the TWI interrupt request will be acti-
vated for as long as the TWINT Flag is high.
• Bits 7:3 – TWS: TWI Status
These five bits reflect the status of the TWI logic and the Two-wire Serial Bus. The different sta-
tus codes are described later in this section. Note that the value read from TWSR contains both
the 5-bit status value and the 2-bit prescaler value. The application designer should mask the
prescaler bits to zero when checking the Status bits. This makes status checking independent of
prescaler setting. This approach is used in this datasheet, unless otherwise noted.
• Bit 2 – Reserved Bit
This bit is reserved and will always read as zero.
• Bits 1:0 – TWPS: TWI Prescaler Bits
These bits can be read and written, and control the bit rate prescaler.
Table 20-7.
To calculate bit rates, see
in the equation.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
TWPS1
0
0
1
1
TWI Bit Rate Prescaler
TWD7
TWS7
R/W
R
7
1
7
1
TWD6
TWS6
R/W
“Bit Rate Generator Unit” on page
R
6
1
6
1
TWD5
TWS5
TWPS0
R/W
R
5
1
5
1
0
1
0
1
TWD4
TWS4
R/W
R
4
1
4
1
Prescaler Value
1
4
16
64
TWD3
TWS3
R/W
R
3
1
3
1
182. The value of TWPS1:0 is used
TWD2
R/W
R
2
0
2
1
–
TWPS1
TWD1
R/W
R/W
1
1
1
0
ATmega32A
TWPS0
TWD0
R/W
R/W
0
1
0
0
TWDR
TWSR
204