AN2841 Freescale Semiconductor / Motorola, AN2841 Datasheet - Page 2

• Manufacturer Part Number: AN2841
• Description: Using the Hall Decoder (HD) eTPU Function
• Manufacturer: Freescale Semiconductor / Motorola

Function Description
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The HD function uses one to four eTPU channels configured as inputs. The primary purpose of this
function is to decode the signals derived from Hall effect sensors used with a brushless motor, and perform
commutations of PWM phases. HD function calculates the following parameters for the CPU:
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Revolution_counter
Revolution_period
Sector - This parameter determines the position of the motion system in one of the sectors. Sector
parameter value is encoded based on the input signal states; see
Direction - This parameter determines the direction of the motion system. A Direction value of 0
indicates a positive (incremental) direction, other values a negative (decremental) direction. The
Direction is calculated only in configurations with 3 or 4 input channels (phases).
Revolution Counter - This parameter determines the number of motion system revolutions. The
Revolution counter is incremented or decremented on each revolution, based on the current
direction. The Revolution Counter is calculated only in configurations with 3 or 4 input channels
(phases).
Sector_period
Function Description
Direction
Sector
Bit:
Using the Hall Decoder (HD) eTPU Function, Rev. 0
PWMC
PWMC
PWMC
HD
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Commutation of PWM Phases
Figure 2. Encoding Sector Parameter
Phase D Pin State
Figure 1. Functionality of HD
Not Used
Phase C Pin State
Phase B Pin State
4
Phase A Pin State
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Sector_period
2
1
Figure
0
Sector_period Sector_period
2.
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