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Two sensors, two buses, six tasks, one watchdog.

This tutorial makes a firmware production-ready: strict periodic scheduling, stack size validation, and hardware-level crash recovery.

Ready? Let's go.

Mutexes protect, semaphores signal.

But in some situations you need a bit more: A callback that fires on its own schedule, a direct line between an ISR and a task, and a way to say "do not start until everything is ready."

Tasks are great, queues as well.

But as soon as several tasks want to use the same resource at the same time, things get messy fast.

When it comes to dividing the time to share tasks, a simple microcontroller sometimes needs a friend.

This friend is called FreeRTOS and will help our dear STM32 to dispatch tasks as if each one was written for the CPU entirely.

Let's see this.

Every smartphone is nowadays provided with an accelerometer.

In this tutorial we are going to see how to retrieve X, Y and Z values from the LSM303DLHC accelerometer on the STM32F3Discovery board.

And to achieve this goal we'll use I2C bus communication.

So far we have blinked LEDs, rotated them with a timer, caught a button interrupt, and sent text over UART.

Time to talk to an external chip.

At some point, blinking LEDs are not enough to understand what your code is actually doing.

You need to print things.

This tutorial shows how to redirect printf() to a serial port on the STM32F3Discovery with a FTDI TTL adapter.

Santa is impressed by the rotating LEDs but now he wants to control them.

Let's add a push button with the EXTI (External Interrupt).

Our Christmas tree is almost ready.

In our previous tutorial we saw how to blink all LEDs at the same time.

The lights are blinking but Santa thinks it's too static.

Let's make them rotate.

Christmas is near (only 6 months), so we have to prepare our xmas tree.

What a better option than using our dear STM32F3Discovery board as a Christmas lights?

Let's see this in this tutorial.

(And yes, Santa Claus is watching you, so be kind.)