Feature: Automotive
of telemetry information to be retrieved such as: • Diagnostics; • Motor speed; • Average supply current; • Supply voltage; • Chip temperature; • Demand input; • Applied bridge peak duty cycle; • Applied phase advance. Beyond these special registers, the
remaining ones allow the specifi c motor application to be tuned and faults to be enabled or disabled, such as current limit and gate drive faults.
Dedicated motor drivers are
interesting because they sum up everything that needs to be configured to run the motor into a few dozen configuration registers. This dramatically reduces the software overhead otherwise existing on a microcontroller and, perhaps more importantly, dramatically reduces software development and maintenance costs. Driving the BLDC is then nothing more than sending a PWM that needs no overhead in a microcontroller, or enabling the motor bit and providing an SPI-based demand input to spin the BLDC.
Using the A4964KJPTR-T T e A4964KJPTR-T is fairly straight- forward to interface to, but there are several ways to simplify and speed up its development: • T e status register is returned on the SPI interface during every write to the chip and is not available as a dedicated, addressable register. T is means that driver code needs to monitor the SPI bus SDO line whilst writing to the chip, to get status information.
• Fault information is included in the status register, but an overview of chip status is available in every SPI
Figure 3: The Texas Instruments C2000 microcontrollers are designed for motor-control applications. This image shows an example application with the microcontroller at the centre, with the required and optional circuitry to drive a BLDC motor
20 April 2022
www.electronicsworld.co.uk
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