C868 Datasheet, PDF (51/82 Pages) Infineon Technologies AG – 8-Bit Single-Chip Microcontroller

C868
For Brushless-DC motors there is a special mode (MSEL6x = ’1000b’) which is
triggered by a change of the Hall-inputs (CCPOSx). This mode shows the capabilities of
the CCU6. Here T12’s channel 0 acts in capture function, channel 1 and 2 in compare
function (without output modulation) and the multi-channel-block is used to trigger the
output switching together with a possible modulation of T13.
After the detection of a valid Hall edge the T12 count value is captured to channel 0
(representing the actual motor speed) and resets the T12. When the timer reaches the
compare value in channel 1, the next multi-channel state is switched by triggering the
shadow transfer of bit field MCMP (if enabled in bit field SWEN). This trigger event can
be combined with several conditions which are necessary to implement a noise filtering
(correct Hall event) and to synchronize the next multi-channel state to the modulation
sources (avoiding spikes on the output lines). This compare function of channel 1 can be
used as a phase delay for the position input to the output switching which is necessary
if a sensorless back-EMF technique is used instead of Hall sensors. The compare value
in channel 2 can be used as a time-out trigger (interrupt) indicating that the motors
destination speed is far below the desired value which can be caused by a abnormal load
change. In this mode the modulation of T12 has to be disabled (T12MODENx = ’0’).
CC60
act. speed
CC61 phase delay
ch0 gets
captured
value for
act. speed
CC62
timeout
capture
event resets
T12
CCPOS0
1
1
1
0
CCPOS1
0
0
1
1
CCPOS2
1
0
0
0
CC6x
COUT6y
ch2 compare
for timeout
ch1 compare
for phase delay
0
0
1
0
1
1
Figure 0-2 Timer T12 Brushless-DC Mode (MSEL6x = 1000)
Data Sheet
51
V 1.0, 2003-05