XC886/888CLM
Capture/Compare Unit 6
User’s Manual
14-21
V1.3, 2010-02
CCU6, V 1.0
14.1.6
Hall Sensor Mode
In
Brushless-DC
motors, the next multi-channel state values depend on the pattern of
the Hall inputs. There is a strong correlation between the
Hall pattern
(CURH) and the
modulation pattern
(MCMP). Because of different machine types, the modulation
pattern for driving the motor can vary. Therefore, it is beneficial to have wide flexibility in
defining the correlation between the Hall pattern and the corresponding modulation
pattern. The CCU6 offers this by having a register which contains the actual Hall pattern
(CURHS), the next expected Hall pattern (EXPHS), and its output pattern (MCMPS). At
every correct Hall event, a new Hall pattern with its corresponding output pattern can be
loaded (from a predefined table) by software into the register MCMOUTS. This shadow
register can also be loaded by a write action on MCMOUTS with bit STRHP = 1. In case
of a phase delay (generated by T12 channel 1), a new pattern can be loaded when the
multi-channel mode shadow transfer (indicated by bit STR) occurs.
14.1.6.1
Sampling of the Hall Pattern
The Hall pattern (on CCPOSx) is sampled with the module clock f
CCU6
. By using the
dead-time counter DTC0 (mode MSEL6x = 1000
B
), a hardware
noise filter
can be
implemented to suppress spikes on the Hall inputs. In case of a Hall event, the DTC0 is
reloaded, and it starts counting and generates a delay between the detected event and
the sampling point. After the counter value of 1 is reached, the CCPOSx inputs are
sampled (without noise and spikes) and are compared to the current Hall pattern
(CURH) and to the expected Hall pattern (EXPH). If the sampled pattern equals to the
current pattern, it means that the edge on CCPOSx was due to a noise spike and no
action will be triggered (implicit noise filter by delay). If the sampled pattern equals to the
next expected pattern, the edge on CCPOSx was a correct Hall event, and the bit CHE
is set which causes an interrupt.
If it is required that the multi-channel mode and the Hall pattern comparison work
independently of timer T12, the delay generation by DTC0 can be bypassed. In this case,
timer T12 can be used for other purposes.
Bit field HSYNC defines the source for the sampling of the Hall input pattern and the
comparison to the current and the expected Hall pattern bit fields. The hall compare
action can also be triggered by software by writing a 1 to bit SWHC. The triggering
sources for the sampling by hardware include:
•
Any edge at one of the inputs CCPOSx (x = 0 - 2)
•
A T13 compare-match
•
A T13 period-match
•
A T12 period-match (while counting up)
•
A T12 one-match (while counting down)
•
A T12 compare-match of channel 0 (while counting up)
•
A T12 compare-match of channel 0 (while counting down)
*