ATmega48 Automotive Atmel Corporation, ATmega48 Automotive Datasheet - Page 58
ATmega48 Automotive
Manufacturer Part Number
ATmega48 Automotive
Description
Manufacturer
Atmel Corporation
Specifications of ATmega48 Automotive
Flash (kbytes)
4 Kbytes
Pin Count
32
Max. Operating Frequency
16 MHz
Cpu
8-bit AVR
# Of Touch Channels
12
Hardware Qtouch Acquisition
No
Max I/o Pins
23
Ext Interrupts
24
Usb Speed
No
Usb Interface
No
Spi
2
Twi (i2c)
1
Uart
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
No
Crypto Engine
No
Sram (kbytes)
0.5
Eeprom (bytes)
256
Self Program Memory
NO
Dram Memory
No
Nand Interface
No
Picopower
No
Temp. Range (deg C)
-40 to 125
I/o Supply Class
2.7 to 5.5
Operating Voltage (vcc)
2.7 to 5.5
Fpu
No
Mpu / Mmu
no / no
Timers
3
Output Compare Channels
6
Input Capture Channels
1
Pwm Channels
6
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
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12.2.2
12.2.3
12.2.4
58
Atmel ATtiny24/44/84 [Preliminary]
Toggling the Pin
Switching Between Input and Output
Reading the Pin Value
If PORTxn is written logical one when the pin is configured as an output pin, the port pin is
driven high (one). If PORTxn is written logical zero when the pin is configured as an output pin,
the port pin is driven low (zero).
Writing a logical 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-impedance 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} = 0b10) as an intermediate step.
Table 12-1 on page 58
Table 12-1.
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 59
pin value. The maximum and minimum propagation delays are denoted t
respectively.
DDxn
0
0
0
1
1
PORTxn
shows a timing diagram of the synchronization when reading an externally applied
0
1
1
0
1
Port Pin Configurations
(in MCUCR)
summarizes the control signals for the pin value.
PUD
X
0
1
X
X
Figure 12-2 on page
Output
Output
Input
Input
Input
I/O
Pull-up
Yes
No
No
No
No
57, the PINxn Register bit and the pre-
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
7701E–AVR–02/11
Figure 12-3
and t
pd,min
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