Starting code

led.c

void setup_led() {
    // Configure GPIO
    RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
    // Configure PA8 (TIM1_CH1) for LED data output
    GPIOA->MODER |= (2 << (2 * 8));
    GPIOA->OSPEEDR |= (3 << (2 * 8));
    GPIOA->AFR[1] |= 0x02; // Configure channel mode for PWM mode 1 (Table 14, TIM1_CH1)

    // Configure TIM1
    RCC->APB2ENR |= RCC_APB2ENR_TIM1EN;
    TIM1->CR1 &= ~TIM_CR1_CEN;
    // Enable capture compare PWM mode
    TIM1->CCMR1 |= TIM_CCMR1_OC1M_1 | TIM_CCMR1_OC1M_2 | TIM_CCMR1_OC1PE;
    TIM1->CCER |= TIM_CCER_CC1E; // use capture compare 1 as output
    TIM1->CR1 &= ~TIM_CR1_CMS;
    TIM1->CR1 &= ~TIM_CR1_DIR;
    TIM1->PSC = 8 - 1;
    TIM1->ARR = 7 - 1;
    // Configure the timer so that an update event triggers a DMA transfer.
    TIM1->DIER |= TIM_DIER_CC1DE;
//    TIM1->DIER |= TIM_DIER_UDE;
    // Don't use timer interrupt
//    TIM1->DIER |= TIM_DIER_UIE;
//    NVIC->ISER[0] |= 1<<TIM1_BRK_UP_TRG_COM_IRQn;

    // Configure DMA
    // Use DMA channel 2 because Table 30 (TIM1_Ch1 => DMA1_Ch2)
    RCC->AHBENR |= RCC_AHBENR_DMA1EN;
    DMA1_Channel2->CCR &= ~DMA_CCR_EN;

    DMA1_Channel2->CMAR = (uint32_t) playercolor; // Copy from the led table
    DMA1_Channel2->CPAR = (uint32_t)(&(TIM1->CCR1)); // Copy to the CCR for the PWM
    DMA1_Channel2->CNDTR = sizeof playercolor; // 24 LEDs in ring, same size as ledtable
    DMA1_Channel2->CCR &= ~(DMA_CCR_MEM2MEM | DMA_CCR_MSIZE_1 | DMA_CCR_PSIZE_1);
    DMA1_Channel2->CCR |= DMA_CCR_MSIZE_0; // MSIZE 16-bit
    DMA1_Channel2->CCR |= DMA_CCR_PSIZE_0; // PSIZE 16-bit
    DMA1_Channel2->CCR |= DMA_CCR_DIR | DMA_CCR_MINC | DMA_CCR_CIRC; // DMA_CCR_CIRC

    // Enable these two to view IRQHandler
//    DMA1_Channel2->CCR |= DMA_CCR_TCIE | DMA_CCR_TEIE;
//    NVIC->ISER[0] |= 1<<DMA1_Channel2_3_IRQn;

    // Enable everything
    DMA1_Channel2->CCR |= DMA_CCR_EN;
    TIM1->CR1 |= TIM_CR1_CEN;
}