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HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
Several registers are used to control the noise filter. The HNF_EN bit in the HNF_MSEL register
is used as the overall enable/disable bit for the noise filter. It is necessary to enable CMP1, CMP2
and CMP3 hysteries function before the camparators
are
used during motor control sensorless
applications.
HNF_EN bit
Status
0
Noise filter off – HA/HB/HC bypass the noise filter
1
Noise filter on
Hall Sensor Noise Filter Enable
The sampling frequency of the Hall noise filter is setup using the HFR_SEL [2:0] bits.
The HCK_N [4:0] bits in the HCHK_NUM register are used to setup the Hall Sensor input compare times.
HCK_N [4:0] × Sampling space=Anti-noise ability=Hall Delay Time.
It should be noted that longer Hall delay time will result in higher rotor speed feedback signal
distortion.
Hall Sensor Delay Function
The Hall sensor function in the device includes a Hall delay function which can implement a signal
phase forward or phase backward operation. The following steps, which should be executed before
the Hall Decoder is enabled, show how this function is activated.
• Step 1
Set the Hall Decode table to select either the phase forward or phase backward function.
• Step 2
Select which TM is used to generate the Delay Time by programming the CTM_SEL1~CTM_
SEL0 bits and set the selected TM to run in the Compare Match Output Mode.
• Step 3
Use the HDLY_MSEL bit to select the Hall Delay circuit operating mode. The default value of
HDLY_MSEL is zero which will disable the Hall Delay circuit. If the HDLY_MSEL bit is set
high, then the Hall Delay circuit will be enabled.
• Step 4
Enable the Hall Decoder using the HDCEN bit.
The following points should be noted regarding the HDLY_MSEL bit.
• When this bit is low, BUF1[2:0] and BUF2[2:0] will be cleared to zero.
• When this bit is low, PTM0, PTM1 and PTM2 remain their original TM functions.
• When the bit is high, the TM which is selected by the Delay function will be dedicated for use by
the Hall Delay circuit. In this case, the original TM functions will still remain active except for
the PTnON bit which will be controlled automatically by the hardware. And the selected PTM
should be properly configured according to the requirement.
With regard to the selected PTM functions the following notes should be taken before the Delay
function is enabled.
• Keep
P
TnON=0 and
P
TnPAU=0.
• The
P
TM should be set in the Compare Match Output Mode.
• Set PTnCCLR=1, therefore the
PTM
counter is cleared with a comparator A match condition.
• Setup the Delay time by properly setting PTMn CCRA and TCKn.
After the Delay function is enabled by setting the HDLY_MSEL bit from low to high, the Delay time
must not be more than one step time of the Hall input, otherwise the output can not be anticipated
and will drop out of step. One Hall cycle includes six steps.