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By Milan Brejl, Ph.D.

Functional Overview

The 3-phase Hall Sensor Decoder (3HD) TPU Function is useful for decoding information from a Hall sensor signal in a motion control system. The function uses three input channels to obtain this information for the CPU:•position in one of six sectors,

•direction,

•period of last revolution updated 6-times per revolution,•

revolution counter.Figure 1 illustrates the functionality.

Figure 1. Signals processed by 3HD TPU function and corresponding values

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Function Configuration

Unlike most of the functions in the MC TPU Library, the 3HD is single-function, and not a member of a function set. There are no restrictions on channel assigment – it can run on any three channels.

Table 1 shows the configuration options and restrictions.

openapiThe three Hall sensor signals are called Phase A, Phase B and Phase C. The

Host Sequence (HSQ) bit 0 is used to determine Phase C, which updates the revolution counter in addition to other processing activities common to all phases. The HSQ is also used for other configur

ation options – refer to the detailed function descriptions.

Table 2 shows an example of configuration. The Phase A signal is connected to channel 0, Phase B to channel 1 and Phase C to channel 2. The TCR1 clock is selected for all timing operations.

In this configuration, when no other functions run on the same TPU, the 3HD can receive and process input transitions at a rate of up to 690 kcounts per second at 40MHz IMB clock.

Table 1. 3HD TPU function configuration options and restrictions

TPU function How many

channels

Assignable channels

3HD

3any 3 channels

Table 2. Example of configuration

Channel

TPU function

HSQ Priority 03HD 00middle 13HD 00middle 2

3HD

middle

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Function Configuration

Table 3 shows the TPU function code sizes.

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Configuration Order The CPU configures the TPU as follows.

1.Disables the channels by clearing the two channel priority bits on each

channel used (not necessary after reset).

蝉式2.Selects the channel functions on all used channels by writing the

function numbers to the channel function select bits.3.Initializes function parameters. The parameters PinAdrPrev_A,

PinAdrNext_A, PinAdrPrev_B, PinAdrNext_B and RC initialization value must be set before initialization.4.Set the HSQ (Host Sequence) bits to identify Phase C channel and to

select TCR1 or TCR2 clock. The clock selection must be the same on all channels.

5.Issues an HSR (Host Service Request) type %10 all 3HD channels to

initialize decoding.

6.Enables servicing by assigning high, middle or low priority to the channel

priority bits. All Phase A, Phase B and Phase C channels should be assigned the same priority.

NOTE:

A CPU routine that configures the TPU can be generated automatically using the MPC500_Quick_Start Graphical Configuration Tool.

Table 3. TPU function code sizes

TPU function

Code size

3HD

63 µ instructions + 8 entries = 71 long words

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Detailed Function Description

3-phase Hall Sensor Decoder (3HD)

The 3HD operates on three channels and processes the incoming Hall sensor signals. As a result of this processing, the Sector parameter gets a value that reflects the position of a motion system in one of six sectors. The state of the Hall sensor signals and the corresponding Sector value is listed in Table 4.

Table 4. Hall sensor signal states and corresponding Sector value

A Sector value of 0 or 7 indicates an illegal state of the Hall sensor signals.The Sector value history determines the direction of the motion system. The Direction parameter can be assigned a value of 0 or 1. See Table 5.Table 5. Sector value sequence and corresponding Direction value

The Period value is calculated each time the sector is changed. The Period value is the TCR time of last revolution. It is measured from the last edge of similar type (low-high / high-low), on the same channel, to the current edge – see Figure 1 and Figure 2. This method eliminates inaccuracies in the Hall sensor signals. The Period parameter does not contain a valid value during the first revolution after initialization, or after a change of direction.

Phase A

Phase B

Phase C

Sector 10041106010201130011101500001117

Sector value sequence Direction

4, 6, 2, 3, 1, 5, 4,...04, 5, 1, 3, 2, 6, 4,...

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Detailed Function Description

Figure 2. Hall sensor signals in opposite direction to Figure 1 and corresponding values

Two function modes are provided:

•TCR1 clock selected •

TCR2 clock selected

The selected mode is determined by the HSQ bit 1. The user has to select the same mode on all channels.

The function provides interpolation support. The parameters LastEdgeT and ActualT are updated on a Host Service Request HSR = 11. LastEdgeT then has the value of the last incoming edge time in the TCR clocks and ActualT has the current value of the TCR clock.

李琦家庭背景The CPU program should use 32-bit reads to ensure coherency of the two parameters. This applies to coherent reads of LastEdgeT and ActualT as well as the Sector and TCR_VALUE, which is necessary for interpolation calculations.

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