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Motorola M68HC08 User Manual

Page 92

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Software Design

Designer Reference Manual

DRM028 — Rev 0

92

Software Design

MOTOROLA

Current measurement and current calibration when PWM is OFF

Before testing of the start switch, dc-bus current is measured when
PWM is OFF. This way the dc-bus current measurement path is
calibrated. The calibrated value Offset0_Curr is used for the final
current calculation.

This offset on the ADC input should ideally be 1.65 V at 0 dc-bus current.

If the sensed value exceeds the limit (Offset_Max_Curr) when PWM
is OFF, this indicates some hardware error, and the control flow
enters into the fault state:

Start condition test

The start condition is tested. If in manual mode (PCMode = 0), the
start condition is a movement in the switch from stop to start. In PC
master software mode (PCMode = 1), the start condition in switch
start position and StartCtrl = 1. If start condition valid then Strt_F is
set, Stop_F is cleared, and the next state entered.

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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