ATtiny2313 Atmel Corporation, ATtiny2313 Datasheet - Page 48

• Manufacturer Part Number: ATtiny2313
• Manufacturer: Atmel Corporation

Specifications of ATtiny2313

• Flash (kbytes): 2 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 4
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 18
• Ext Interrupts: 18
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.12
• Eeprom (bytes): 128
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

Switching Between
Input and Output
Reading the Pin Value
48
ATtiny2313
When switching between tri-state ({DDxn, PORTxn} = 0b00) and output high ({DDxn, PORTxn}
= 0b11), an intermediate state with either pull-up enabled {DDxn, PORTxn} = 0b01) or output
low ({DDxn, PORTxn} = 0b10) must occur. Normally, the pull-up enabled state is fully accept-
able, as a high-impedant environment will not notice the difference between a strong high driver
and a pull-up. If this is not the case, the PUD bit in the MCUCR Register can be set to disable all
pull-ups in all ports.
Switching between input with pull-up and output low generates the same problem. The user
must use either the tri-state ({DDxn, PORTxn} = 0b00) or the output high state ({DDxn, PORTxn}
= 0b11) as an intermediate step.
Table 22
Table 22. Port Pin Configurations
Independent of the setting of Data Direction bit DDxn, the port pin can be read through the
PINxn Register bit. As shown in
tute a synchronizer. This is needed to avoid metastability if the physical pin changes value near
the edge of the internal clock, but it also introduces a delay.
the synchronization when reading an externally applied pin value. The maximum and minimum
propagation delays are denoted t
Figure 23. Synchronization when Reading an Externally Applied Pin value
DDxn
0
0
0
1
1
INSTRUCTIONS
SYSTEM CLK
SYNC LATCH
summarizes the control signals for the pin value.
PORTxn
0
1
1
0
1
PINxn
r17
(in MCUCR)
PUD
X
X
X
0
1
Figure
pd,max
Output
Output
XXX
Input
Input
Input
I/O
and t
22, the PINxn Register bit and the preceding latch consti-
Pull-up
pd,min
Yes
No
No
No
No
t
pd, max
0x00
respectively.
XXX
Comment
Tri-state (Hi-Z)
Pxn will source current if ext. pulled
low.
Tri-state (Hi-Z)
Output Low (Sink)
Output High (Source)
t
pd, min
Figure 23
in r17, PINx
shows a timing diagram of
0xFF
2543L–AVR–08/10