Initialization

As with every other peripheral, we’ll have to initialize this timer before we can use it. And justas in the previous section, initialization is going to involve two steps: powering up the timer andthen configuring it.

Powering up the timer is easy: We just have to set TIM6EN bit to 1. This bit is in the APB1ENRregister of the RCC register block.

    // Power on the TIM6 timer
    rcc.apb1enr.modify(|_, w| w.tim6en().set_bit());

The configuration part is slightly more elaborate.

First, we’ll have to configure the timer to operate in one pulse mode.

    // OPM Select one pulse mode
    // CEN Keep the counter disabled for now
    tim6.cr1.write(|w| w.opm().set_bit().cen().clear_bit());

Then, we’ll like to have the CNT counter operate at a frequency of 1 KHz because our delayfunction takes a number of milliseconds as arguments and 1 KHz produces a 1 millisecond period. Forthat we’ll have to configure the prescaler.

    // Configure the prescaler to have the counter operate at 1 KHz
    tim6.psc.write(|w| w.psc().bits(psc));

I’m going to let you figure out the value of the prescaler, psc. Remember that the frequency ofthe counter is apb1 / (psc + 1) and that apb1 is 8 MHz.