uint32_t getTrueRandomNumber(void) {

  ADC_InitTypeDef ADC_InitStructure;

  //enable ADC1 clock
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);

  // Initialize ADC 14MHz RC
  RCC_ADCCLKConfig(RCC_ADCCLK_HSI14);
  RCC_HSI14Cmd(ENABLE);
  while (!RCC_GetFlagStatus(RCC_FLAG_HSI14RDY))
    ;

  ADC_DeInit(ADC1);
  ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
  ADC_InitStructure.ADC_ScanDirection = ADC_ScanDirection_Backward;
  ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
  ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_TRGO; //default
  ADC_Init(ADC1, &ADC_InitStructure);

  //enable internal channel
  ADC_TempSensorCmd(ENABLE);

  // Enable ADCperipheral
  ADC_Cmd(ADC1, ENABLE);
  while (ADC_GetFlagStatus(ADC1, ADC_FLAG_ADEN) == RESET)
    ;

  ADC1->CHSELR = 0; //no channel selected
  //Convert the ADC1 temperature sensor, user shortest sample time to generate most noise
  ADC_ChannelConfig(ADC1, ADC_Channel_TempSensor, ADC_SampleTime_1_5Cycles);

  // Enable CRC clock
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_CRC, ENABLE);

  uint8_t i;
  for (i = 0; i < 8; i++) {
    //Start ADC1 Software Conversion
    ADC_StartOfConversion(ADC1);
    //wait for conversion complete
    while (!ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC)) {
    }

    CRC_CalcCRC(ADC_GetConversionValue(ADC1));
    //clear EOC flag
    ADC_ClearFlag(ADC1, ADC_FLAG_EOC);
  }

  //disable ADC1 to save power
  ADC_Cmd(ADC1, DISABLE);
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, DISABLE);

  return CRC_CalcCRC(0xBADA55E5);
}

#define RANDOM_MIN (1)
#define RANDOM_MAX (7)

volatile uint32_t random_num;

random_num = RANDOM_MIN + getTrueRandomNumber()%RANDOM_MAX;

static unsigned long int next = 1;

int rand(void) // RAND_MAX assumed to be 32767
{
    next = next * 1103515245 + 12345;
    return (unsigned int)(next/65536) % 32768;
}

void srand(unsigned int seed)
{
    next = seed;
}

/* Initialize SSP for slave device */
void ssp_sensor_init(void);

/* Send debug message over SSP.
 * Attention: this function should not be used when more than one device connected to master! */
void ssp_send_debug_msg(char *ptr, int len);

/* Should be called as frequently as possible from main loop or OS thread */
void ssp_sensor_task_tick(void);

/* Returns current state of leds and vibro according to animation tasks received from master */
void ssp_get_leds_vibro_state(uint8_t* r, uint8_t* g, uint8_t* b, uint8_t* vibro);

typedef struct {
   SSP_IR_Buffer buffer;
   SSP_Address sensor_address;
} SSP_IR_Message;

typedef struct {
   SSP_Address address[SSP_MAX_SENSORS_COUNT];
   uint16_t size;
} SSP_Registered_Addrs_List;

/* Initialize SSP for master device */
void ssp_master_init(void);

/* Should be called as frequently as possible from main loop or OS thread */
void ssp_master_task_tick(void);

/* Send IR buffer request to sensor with address specified. Result will be put into queue */
void ssp_push_ir_request(SSP_Address target_device);

/* Get IR buffer from queue and pop it. NULL if no data received */
SSP_IR_Message* ssp_get_next_ir_buffer();

/* Send animation task to sensor by address. Broadcast acceptable */
void ssp_push_animation_task(SSP_Address target, SSP_Sensor_Animation_Task* task);

/* Begin address discovering procedure */
void ssp_start_address_discovering();

/* Get addres discovering status. Non-zero if discovering in process */
uint8_t ssp_is_address_discovering_now();

/* Force stopping address discovering */
void ssp_stop_address_discovering();

/* Non-zero if ssp is busy now. This should be checked before any transmission over SSP */
uint8_t ssp_is_busy();

extern SSP_Registered_Addrs_List ssp_registered_addrs;

void ssp_send_data(uint8_t* data, uint16_t size);

void ssp_receive_byte(uint8_t byte);