MCUXpresso tutorial: I2C using the Pins/Clocks/Peripherals Config tools and lpcxpresso55s69 SDK

I selected the Bosch BME280 environmental sensor as the heart of my OKdo E1-based weather station. It is convenient to use, and I can prototype with the Mikroe Weather Click board MIKROE-1978. But the sensor is accessed over I2C, and that is my least favourite of the communication interfaces. In this short tutorial, I show you how the MCUXpresso Config tools (Pins, Clocks, Peripherals) are used to set up the I2C driver from the MCUXpresso lpcxpresso55S69 SDK. And very quickly, I am able to communicate with the BME280 sensor.

Reading BME280 “ID” register via I2C
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Investigating ARM Cortex® M33 core with TrustZone® – Using the Clocks Config Tool

Clocks. I’ve always found the clock setting of a microcontroller one of the hardest things to get right during my embedded career. If I re-use the clocks setup from the development board it is easy. But if the development board runs from a crystal and I want to use the free-running internal clock, or if I change to a different frequency crystal (and keep the same PLL output frequency) it always gets difficult. To be honest I’ve developed some projects early in my career and never been 100% certain at what frequency the core, flash and peripherals are running.

That’s not good.

The Config Tools within the MCUXpresso brand have greatly simplified setting up the pins, clocks, peripherals (and next week – Trusted Execution Environment 🙂 ) on NXP microcontrollers. So I’m going to quickly show you how to set up 3 different clock arrangements, and output the main clock to an output pin named CLK_OUT.

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NXP MCUXpresso Software and Tools with Clocks Tool

About a year ago, on December 7th 2015, Freescale and NXP have announced the completion of their merger.  Now it is Qualcomm which wants to acquire NXP? It looks like these mergers are happening faster and faster. The reality is that merging products take more time than anticipated, and nearly one year later I can see the outcome of what comes out of the marriage between Freescale and NXP or between Kinetis and LPC: NXP has announced the MCUXpresso software and tools for Kinetis and LPC microcontroller:

Introducing MCUXpresso

Introducing MCUXpresso (Source: NXP video)

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