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AN4539

Getting the kitchen ready

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1

Getting the kitchen ready

In this section, we’ll make sure to have all the necessary ingredients ready before starting,

so that we can concentrate on the HRTIM programming only.

The following documents are to be considered as reference:

•

STM32F334x4/x6/x8 Datasheet

•

STM32F334x4/x6/x8 Errata sheet

•

•

UM1733: Getting Started with STM32F334 Discovery Kit

•

UM1735: Discovery kit for STM32F3 series - with STM32F334C8 MCU

•

UM1736: Getting started with STM32F334 Discovery software development tools

•

AN4885: High brightness LED dimming using the STM32F3348 Discovery

A preliminary reading of the HRTIM chapter in the RM0364 will be useful.

1.1

Prerequisites

Before enjoying the flavors of the HRTIM, let’s list the prerequisites. It is expected from the

reader basic C programming skills and minimal experience on MCUs and development

environments, as well as a theoretical background on switched mode power supplies.

Control strategies and components dimensioning details are exceeding the scope of this

application note, they are available in a vast literature.

For the sake of simplicity, this cookbook only considers logic signals or analog voltages

conditioned to be directly handled by the MCU, so as to be voltage level agnostic. However

some references are made to external components interfacing and side effects from power

switchings, whenever the timer or MCU has some features to handle them.

Last, it is reminded that it is required to have power applications operated by skilled

technical personnel to avoid risks of electrical shocks, burns or even death, should the

STM32F334 and the HRTIM may be used in applications with hazardous voltage levels.

1.2

Hardware set-up

The STM32F334 Discovery board is a very affordable tool and is the best option to start

(and go on) experimenting with the HRTIM (order code: STM32F3348-DISCO). It includes

the programming interface and a USB cable is the only necessary additional material to

have the chip programmed and debugged. All I/Os are made available on 2.54 mm spaced

pins so that it can also be connected to a perfboard / stripboard / breadboard. The kit also

features two power converters: an inverted buck for LED drive and a low-voltage buck/boost

converter with independent inputs and outputs.

An oscilloscope is mandatory, eventually coupled with a logic analyzer for the configurations

where more than 4 channels must be monitored. To visualize the subtle high-resolution

steps, the oscilloscope has to have a sampling rate above 1GS/s at least with an option to

have interleaved acquisition so as to increase the timing accuracy above the 217ps timer

resolution.