ATTINY20-XU Atmel, ATTINY20-XU Datasheet - Page 136

• Manufacturer Part Number: ATTINY20-XU
• Description: MCU AVR 2KB FLASH 12MHZ 14TSSOP
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY20-XU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 12MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 12
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• 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: *
• Processor Series: ATtiny
• Core: AVR
• Data Bus Width: 8 bit
• Data Ram Size: 128 B
• Interface Type: SPI, TWI
• Maximum Clock Frequency: 12 MHz
• Number Of Programmable I/os: 12
• Number Of Timers: 2
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

136
ATtiny20
• Bit 5 – DORD: Data Order
When the DORD bit is written to one, the LSB of the data word is transmitted first.
When the DORD bit is written to zero, the MSB of the data word is transmitted first.
• Bit 4 – MSTR: Master/Slave Select
This bit selects Master SPI mode when written to one, and Slave SPI mode when written logic
zero. If SS is configured as an input and is driven low while MSTR is set, MSTR will be cleared,
and SPIF in SPSR will become set. The user will then have to set MSTR to re-enable SPI Mas-
ter mode.
• Bit 3 – CPOL: Clock Polarity
When this bit is written to one, SCK is high when idle. When CPOL is written to zero, SCK is low
when idle. Refer to
marized below:
Table 16-3.
• Bit 2 – CPHA: Clock Phase
The settings of the Clock Phase bit (CPHA) determine if data is sampled on the leading (first) or
trailing (last) edge of SCK. Refer to
functionality is summarized below:
Table 16-4.
• Bits 1:0 – SPR[1:0]: SPI Clock Rate Select 1 and 0
These two bits control the SCK rate of the device configured as a Master. SPR1 and SPR0 have
no effect on the Slave. The relationship between SCK and the I/O clock frequency f
shown in the following table:
Table 16-5.
SPI2X
0
0
0
0
1
1
1
1
CPHA
CPOL
CPOL Functionality
CPHA Functionality
Relationship Between SCK and the I/O Clock Frequency
0
1
0
1
Figure 16-3
SPR1
0
0
1
1
0
0
1
1
and
Figure 16-4
Figure 16-3
Leading Edge
Leading Edge
Sample
Falling
Rising
Setup
SPR0
0
1
0
1
0
1
0
1
for an example. The CPOL functionality is sum-
and
Figure 16-4
SCK Frequency
f
f
f
f
f
f
f
f
clk_I/O
clk_I/O
clk_I/O
clk_I/O
clk_I/O
clk_I/O
clk_I/O
clk_I/O
/
/
/
/
/
/
/
/
4
16
64
128
2
8
32
64
for an example. The CPOL
Trailing Edge
Trailing Edge
Sample
Falling
Rising
Setup
8235B–AVR–04/11
clk_I/O
is