AT90PWM2B-16SE ATMEL [ATMEL Corporation], AT90PWM2B-16SE Datasheet - Page 141

• Manufacturer Part Number: AT90PWM2B-16SE
• Description: 8-bit Microcontroller with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

16.7.1
4317J–AVR–08/10
Frequency distribution
The frequency modulation is done by switching two frequencies in a 16 consecutive cycle frame.
These two frequencies are f
frequency and f
in the frame is (d-16) and the number of f
uted in the frame according to a predefined pattern. This pattern can be as given in the following
table or by any other implementation which give an equivallent evenly distribution.
Table 16-5.
While ‘X’ in the table, f
So for each row, a number of fb2 take place of fb1.
Figure 16-12. Resulting Frequency versus d.
Distribution of fb2 in the modulated frame
Fraction
al
Divider
(d)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
d:
f
b1
0
PWM - cycle
0
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1
Distribution of f
b2
2
1
X
X
X
X
X
X
X
is the nearest base frequency below the wanted frequency. The number of f
3
2
X
X
X
X
X
X
X
X
X
X
X
b2
4
prime to f
3
X
X
X
b1
b2
5
and f
in the modulated frame
4
X
X
X
X
X
X
X
X
X
X
X
X
X
6
b1
b2
in cycle corresponding cycle.
7
where f
5
X
X
X
X
X
8
b2
6
X
X
X
X
X
X
X
X
X
is d. The f
b1
9 10 11 12 13 14 15
is the nearest base frequency above the wanted
7
X
8
X
X
X
X
X
X
X
X
X
X
X
X
X
X
b1
and f
AT90PWM2/3/2B/3B
9
X
X
X
X
X
X
b2
frequencies are evenly distrib-
10
X
X
X
X
X
X
X
X
X
X
11
X
X
f
12
X
X
X
X
X
X
X
X
X
X
X
X
b2
13
X
X
X
X
f
OP
14
X
X
X
X
X
X
X
X
15
141
b1