ATtiny48 Atmel Corporation, ATtiny48 Datasheet - Page 40

• Manufacturer Part Number: ATtiny48
• Manufacturer: Atmel Corporation

Specifications of ATtiny48

• Flash (kbytes): 4 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 12 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 28
• Ext Interrupts: 28
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 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: Yes
• Crypto Engine: No
• Sram (kbytes): 0.25
• Eeprom (bytes): 64
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• 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: 2
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

7.4.2
7.4.3
40
ATtiny48/88
MCUCR – MCU Control Register
PRR – Power Reduction Register
• Bits 7, 3:0 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 6 – BODS: BOD Sleep
The BODS bit must be written to logic one in order to turn off BOD during sleep, see
on page
BODSE in MCUCR. To disable BOD in relevant sleep modes, both BODS and BODSE must first
be set to one. Then, to set the BODS bit, BODS must be set to one and BODSE must be set to
zero within four clock cycles.
The BODS bit is active three clock cycles after it is set. A sleep instruction must be executed
while BODS is active in order to turn off the BOD for the actual sleep mode. The BODS bit is
automatically cleared after three clock cycles.
• Bit 5 – BODSE: BOD Sleep Enable
BODSE enables setting of BODS control bit, as explained in BODS bit description. BOD disable
is controlled by a timed sequence.
The Power Reduction Register (PRR) provides a method to stop the clock to individual peripher-
als to reduce power consumption. The current state of the peripheral is frozen and the I/O
registers can not be read or written. Resources used by the peripheral when stopping the clock
will remain occupied, hence the peripheral should in most cases be disabled before stopping the
clock. Waking up a module, which is done by clearing the bit in PRR, puts the module in the
same state as before shutdown.
Module shutdown can be used in Idle mode and Active mode to significantly reduce the overall
power consumption. In all other sleep modes, the clock is already stopped.
• Bit 7 – PRTWI: Power Reduction TWI
Writing a logic one to this bit shuts down the TWI by stopping the clock to the module. When
waking up the TWI again, the TWI should be re initialized to ensure proper operation.
• Bits 6, 4, 1 – Res: Reserved
These bits are reserved and will always read zero.
• Bit 5 – PRTIM0: Power Reduction Timer/Counter0
Writing a logic one to this bit shuts down the Timer/Counter0 module. When the Timer/Counter0
is enabled, operation will continue like before the shutdown.
Bit
0x35 (0x55)
Read/Write
Initial Value
Bit
(0x64)
Read/Write
Initial Value
39. Writing to the BODS bit is controlled by a timed sequence and an enable bit,
PRTWI
R/W
7
0
R
7
–
0
BODS
R/W
R
6
–
0
6
0
PRTIM0
R/W
BODSE
5
0
R/W
5
0
R
4
–
0
PUD
R/W
4
0
PRTIM1
R/W
3
0
R
3
–
0
PRSPI
R/W
2
0
R
2
–
0
R
1
–
0
R
1
–
0
PRADC
R
0
–
0
R/W
8008H–AVR–04/11
0
0
Table 7-2
MCUCR
PRR