ATtiny28L Atmel Corporation, ATtiny28L Datasheet - Page 43

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ATtiny28L

Manufacturer Part Number
ATtiny28L
Description
Manufacturer
Atmel Corporation
Datasheets

Specifications of ATtiny28L

Flash (kbytes)
2 Kbytes
Pin Count
28
Max. Operating Frequency
4 MHz
Cpu
8-bit AVR
Hardware Qtouch Acquisition
No
Max I/o Pins
11
Ext Interrupts
10
Usb Speed
No
Usb Interface
No
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
No
Crypto Engine
No
Sram (kbytes)
0.03
Self Program Memory
NO
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
1
32khz Rtc
No
Calibrated Rc Oscillator
Yes
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Register Description
Modulation Control Register –
MODCR
Table 18. MCONF2..0 Effect on Duty-cycle and Modulation Period
Note:
1062F–AVR–07/06
MCONF2..0
000
001
010
011
100
101
110
111
In the high-frequency mode, the output is gated with the clock signal. Thus, the on- and off-times will be dependent on the clock
input to the MCU. Also note that when changing from this mode directly to another modulation mode, the output will have a
small glitch. Thus, PA2 should be set to stop the modulated output before changing from this mode.
On-time
X
ONTIM+1
ONTIM+1
ONTIM+1
2 x (ONTIM+1)
3 x (ONTIM+1)
X
Off-time
X
ONTIM+1
2 x (ONTIM+1)
3 x (ONTIM+1)
ONTIM+1
ONTIM+1
X
• Bits 7..3 – ONTIM4..0: Modulation On-time
This 5-bit value +1 determines the number of clock cycles the output pin PA2 is active
(low).
• Bits 2..0 – MCONF2..0: Modulation Configuration Bits 2, 1 and 0
These three bits determine the relationship between the on- and off-times of the modu-
lator, and thereby the duty-cycle. The various settings are shown in Table 18. The
minimum and maximum modulation period is also shown in the table. The minimum
modulation period is obtained by setting ONTIM to zero, while the maximum period is
obtained by setting ONTIM to 31. The configuration values for some common oscillator
and carrier frequencies are listed in Table 17. The relationship between oscillator fre-
quency and carrier frequency is:
If the MCONF register is set to 111, the carrier frequency will be equal to the oscillator
frequency.
Bit
$02
Read/Write
Initial Value
ONTIM4
R/W
7
0
Duty-cycle
100%
50%
33%
25%
67%
75%
Note 1
ONTIM3
R/W
6
0
fcarrier
ONTIM2
Reserved
R/W
5
0
Min Period
X
2 CK
3 CK
4 CK
3 CK
4 CK
1 CK
=
-----------------------------------------------------
(
On-time
ONTIM1
R/W
4
0
fosc
+
ONTIM0
R/W
Off-time
3
0
Max Period
X
64 CK
96 CK
128 CK
96 CK
128 CK
1 CK
MCONF2
R/W
)
2
0
MCONF1
ATtiny28L/V
R/W
1
0
Comment
Unmodulated output
High-frequency output
MCONF0
R/W
0
0
MODCR
43

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