Guppy PRO Technical Manual
V4.1.2
80
PWM: Examples in practice
In this chapter we give you two examples, how to write values in the PWM
registers. All values have to be written in microseconds (µs) in the PWM
registers; therefore, remember always the factor 10
-6
s.
Example 1:
Set PWM with 1kHz at 30% pulse width.
Example 2:
Set PWM with 250 Hz at 12% pulse width.
Pixel data
Pixel data are transmitted as isochronous data packets in accordance with the
1394 interface described in IIDC V1.31. The first packet of a frame is identified
by the 1 in the sync bit (sy) of the packet header.
Formula 2: PWM example 1
Formula 3: PWM example 2
RegPeriod
1
frequency
6
–
10
s
------------------------------------------
1
1kHz
6
–
10
s
------------------------------
1000
=
=
=
RegPulseWidth
RegPeriod
30%
1000
30%
300
=
=
=
RegPeriod
1
frequency
6
–
10
s
------------------------------------------
1
250Hz
6
–
10
s
----------------------------------
4000
=
=
=
RegPulseWidth
RegPeriod
12%
4000
12%
480
=
=
=
0 to 7
8 to 15
16 to 23
24 to 31
data_length
tg
channel
tCode
sy
header_CRC
Video data payload
data_CRC
Table 32: Isochronous data block packet format. Source: IIDC V1.31
sync bit
