ATMEGA8HVD-4MX Atmel, ATMEGA8HVD-4MX Datasheet - Page 63

• Manufacturer Part Number: ATMEGA8HVD-4MX
• Description: MCU AVR 8K FLASH 2.1-8V 4MHZ QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8HVD-4MX

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: POR, WDT
• Number Of I /o: 5
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 2.4 V
• Data Converters: A/D 1x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 85°C
• Package / Case: 18-MLF® Exposed Pad (Staggered Leads), DFN
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Connectivity: -

14.2.2
14.2.3
14.2.4
8052B–AVR–09/08
Toggling the Pin
Switching Between Input and Output
Reading the Pin Value
If PORTxn is written logic one when the pin is configured as an output pin, the port pin is
driven high (one). If PORTxn is written logic zero when the pin is configured as an output pin,
the port pin is driven low (zero).
Writing a logic one to PINxn toggles the value of PORTxn, independent on the value of
DDRxn. Note that the SBI instruction can be used to toggle one single bit in a port.
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
acceptable, 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 14-1
Table 14-1.
Independent of the setting of Data Direction bit DDxn, the port pin can be read through the
PINxn Register bit. As shown in
ceding latch constitute 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.
on page 64
pin value. The maximum and minimum propagation delays are denoted t
respectively.
DDxn
0
0
0
1
1
PORTxn
summarizes the control signals for the pin value.
shows a timing diagram of the synchronization when reading an externally applied
0
1
1
0
1
Port Pin Configurations
(in MCUCR)
PUD
X
0
1
X
X
Figure 14-2 on page
Output
Output
Input
Input
Input
I/O
Pull-up
Yes
No
No
No
No
62, the PINxn Register bit and the pre-
ATmega4HVD/8HVD
Comment
Tri-state (Hi-Z)
Pxn will source current if ext. pulled low.
Tri-state (Hi-Z)
Output Low (Sink)
Output High (Source)
pd,max
Figure 14-3
and t
pd,min
63