diff --git a/source/test/pwm/main.c b/source/test/pwm/main.c
index 343676f..6e381a3 100644
--- a/source/test/pwm/main.c
+++ b/source/test/pwm/main.c
@@ -16,17 +16,163 @@
 #include "list.h"
 #include "shell.h"
 
+#include "stm32f4xx.h"
+
+struct stm32f4_pwm {
+	TIM_TypeDef *timer;
+	const TIM_TimeBaseInitTypeDef *timer_cfg;
+	const TIM_OCInitTypeDef *output_compare_cfg;
+	const TIM_BDTRInitTypeDef *bdtr_cfg;
+	GPIO_TypeDef *port;
+	uint8_t pin_src;
+	const GPIO_InitTypeDef *port_cfg;
+};
+
+static const TIM_TimeBaseInitTypeDef timer_4_cfg = {
+		.TIM_RepetitionCounter = 0x0000,
+		.TIM_Prescaler = ((168000000 / 2 ) / 1000000) - 1,
+		.TIM_ClockDivision = TIM_CKD_DIV1,
+		.TIM_CounterMode = TIM_CounterMode_Up,
+		.TIM_Period = 20000
+};
+
+static const TIM_OCInitTypeDef t4_output_compare_cfg = {
+		.TIM_OutputNState = TIM_OutputNState_Disable,
+		.TIM_OCNPolarity = TIM_OCPolarity_High,
+		.TIM_OCIdleState = TIM_OCIdleState_Reset,
+		.TIM_OCNIdleState = TIM_OCNIdleState_Set,
+		.TIM_OCMode = TIM_OCMode_PWM1,
+		.TIM_OCPolarity = TIM_OCPolarity_High,
+		.TIM_OutputState = TIM_OutputState_Enable,
+		.TIM_Pulse = 1500 // Initiale Pulsweite in Millisekunden
+};
+
+static const TIM_BDTRInitTypeDef t4_bdtr_cfg = {
+		.TIM_OSSRState = TIM_OSSRState_Disable,
+		.TIM_OSSIState = TIM_OSSIState_Disable,
+		.TIM_LOCKLevel = TIM_LOCKLevel_OFF,
+		.TIM_DeadTime = 0x00,
+		.TIM_Break = TIM_Break_Disable,
+		.TIM_BreakPolarity = TIM_BreakPolarity_Low,
+		.TIM_AutomaticOutput = TIM_AutomaticOutput_Disable,
+
+
+		.TIM_AutomaticOutput = TIM_AutomaticOutput_Enable,
+};
+
+static const GPIO_InitTypeDef port_cfg = {
+		.GPIO_Pin = GPIO_Pin_12,
+		.GPIO_Mode = GPIO_Mode_AF,
+		.GPIO_OType = GPIO_OType_PP,
+		.GPIO_PuPd = GPIO_PuPd_UP,
+		.GPIO_Speed = GPIO_Speed_50MHz,
+};
+
+static struct stm32f4_pwm str32f4_pwm = {
+		.timer = TIM4,
+		.timer_cfg = &timer_4_cfg,
+		.output_compare_cfg = &t4_output_compare_cfg,
+		.bdtr_cfg = &t4_bdtr_cfg,
+		.port = GPIOD,
+		.pin_src = GPIO_PinSource12,
+		.port_cfg = &port_cfg,
+};
+
+extern uint32_t SystemCoreClock;
+void pwm_open(struct stm32f4_pwm *pwm)
+{
+	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
+	TIM_OCInitTypeDef  TIM_OCInitStructure;
+
+	/* TIM config */
+	GPIO_InitTypeDef GPIO_InitStructure;
+
+	/* TIM4 clock enable */
+	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);
+
+	/* LEDs are on GPIOD */
+	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
+	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
+	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
+	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
+	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
+	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
+	GPIO_Init(GPIOD, &GPIO_InitStructure);
+	GPIO_PinAFConfig(GPIOD, GPIO_PinSource12, GPIO_AF_TIM4);
+	GPIO_PinAFConfig(GPIOD, GPIO_PinSource13, GPIO_AF_TIM4);
+	GPIO_PinAFConfig(GPIOD, GPIO_PinSource14, GPIO_AF_TIM4);
+	GPIO_PinAFConfig(GPIOD, GPIO_PinSource15, GPIO_AF_TIM4);
+
+	/* pwm set up */
+	/* Compute the prescaler value */
+	uint16_t PrescalerValue = (uint16_t) ((SystemCoreClock /2) / 21000000) - 1;
+
+	/* apb1 clock = 84MHz */
+	/* period_reg = src_clk / presc   / cnt_clk     */
+	/*       4199 = 84MHZ   / (0 + 1) / 20kHz   - 1 */
+
+	/* Time base configuration */
+	TIM_TimeBaseStructure.TIM_Period = 4199;//665;
+	TIM_TimeBaseStructure.TIM_Prescaler = 0;//PrescalerValue;
+	TIM_TimeBaseStructure.TIM_ClockDivision = 1;
+	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
+	TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);
+
+	/* PWM1 Mode configuration: Channel1 */
+	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
+	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
+	TIM_OCInitStructure.TIM_Pulse = 0;
+	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
+	TIM_OC1Init(TIM4, &TIM_OCInitStructure);
+	TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable);
+
+	/* PWM1 Mode configuration: Channel2 */
+	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
+	TIM_OCInitStructure.TIM_Pulse = 0;
+	TIM_OC2Init(TIM4, &TIM_OCInitStructure);
+	TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);
+
+	/* PWM1 Mode configuration: Channel3 */
+	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
+	TIM_OCInitStructure.TIM_Pulse = 0;
+	TIM_OC3Init(TIM4, &TIM_OCInitStructure);
+	TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Enable);
+
+	/* PWM1 Mode configuration: Channel4 */
+	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
+	TIM_OCInitStructure.TIM_Pulse = 0;
+	TIM_OC4Init(TIM4, &TIM_OCInitStructure);
+	TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Enable);
+	TIM_ARRPreloadConfig(TIM4, ENABLE);
+
+	/* TIM4 enable counter */
+	TIM_Cmd(TIM4, ENABLE);
+}
+
 #define TH_STACK_SIZE  256
 stack_t th_stack[TH_STACK_SIZE];
 struct thread_context th_ctx;
 static void th_func(void *arg)
 {
+	uint32_t brightness = 4200 / 2;
+	TIM4->CCR4 = brightness;
 	while(1) {
+		brightness++;
+		if(brightness == UINT32_MAX)
+			brightness = 0;
+#if 0
+		TIM4->CCR3 = 333 - (brightness + 0) % 333; // set brightness
+		TIM4->CCR4 = 333 - (brightness + 166/2) % 333; // set brightness
+		TIM4->CCR1 = 333 - (brightness + 333/2) % 333; // set brightness
+		TIM4->CCR2 = 333 - (brightness + 499/2) % 333; // set brightness
+#endif
+		sleep_ms(1);
 	}
 }
 
 int main(void)
 {
+	pwm_open(&str32f4_pwm);
 	thread_create(&th_ctx, th_stack, TH_STACK_SIZE, th_func, NULL, THREAD_PRIO_LOW);
 
 	schedule_start();