Version vom 4. März 2020, 23:35 Uhr

Feindesign

Im folgenden ist der derzeitig Programmablauf dargestellt. Da dieser Programmablauf zu Interrupt Überlagerungen kommen kann wird das Programm noch so abgeändert, dass der StartOfIntegration Pin über polling abgefragt wird.

ADC Feindesign

Da keine hohe Auflösung des Analog/Digital-Konverters notwendig ist, werden alle Parameter so eingestellt, dass der ADC möglichst schnell seine Werte liefern kann.

 /* ADC struct (definitions can be found in adc.h) */
 static const struct adc_channel_cfg m_2nd_channel_cfg = {
  .gain = ADC_GAIN,  //5 is gain of 1x
  .reference = ADC_REFERENCE,  // default ref. is GND
  .acquisition_time = ADC_ACQUISITION_TIME,  //1 = 5µs, ADC_ACQUISITION_TIME
  .channel_id = ADC_2ND_CHANNEL_INPUT,
  .input_positive = ADC_2ND_CHANNEL_INPUT,
 };

 struct device *get_adc_device(void){
  return device_get_binding(ADC_DEVICE_NAME);
 }

 const struct adc_sequence sequence = {
	.channels = BIT(ADC_2ND_CHANNEL_INPUT),
	.buffer = adc_buffer,
	.buffer_size = sizeof(adc_buffer),
	.resolution = 8,  //8,10,12 ADC_RESOLUTION
	.oversampling = 0, //0, 4
 };

MIDI Feindesign

Da MIDI 31250 Baud statt 115200 Baud (bei UART) verwendet wird diese Baudrate bei Programmbeginn eingestellt.

 initUART0();
 uart_cfg.baudrate = 31250;              //115200 default, 31250 MIDI
 uart_cfg.parity = UART_CFG_PARITY_NONE;
 uart_cfg.stop_bits = UART_CFG_STOP_BITS_1;
 uart_cfg.flow_ctrl = UART_CFG_FLOW_CTRL_NONE;
 uart_cfg.data_bits = UART_CFG_DATA_BITS_8;
 uart_configure(UART0_dev, &uart_cfg);   // Take new settings

Counter Feindesign

Um nebenläufig die Clock des Evaluationsboards mitlesen zu können wurde ein Counter über ein PPI (Programmable Peripheral Interconnect) mit einem GPIO Pin verbunden.

 // Initialize a PPI channel
 void ppi_init(void){
	nrfx_err_t errvalue;
	/*get a ppi channel for CCD CLK to count the pixel*/
	memset(&count_channel_pixel, 0, sizeof(nrf_ppi_channel_t));
	errvalue = nrfx_ppi_channel_alloc(&count_channel_pixel);
	if(errvalue == NRFX_SUCCESS){
		printk("nrfx_ppi_channel_alloc returned Success!\n");
	}
	if(errvalue == NRFX_ERROR_NO_MEM){
		printk("nrfx_ppi_channel_alloc returned Error No Mem!\n");
	}

	/*
	 	Event End Points are used as a trigger.
	*/
	/*Get CCD_CLK = EXT_A0_GPIO_PIN (EET - Event End Point) adress*/
	uint32_t gpiote_event_pixel  = nrfx_gpiote_in_event_addr_get(CCD_CLK);
	
       /*
		Task End Points are getting triggered by Event End Points
	  Get Counter (TEP - Task End Point) adress
	*/
	/*nrfx_timer_task_address_get - Function for returning the address of a specific timer task.
		Parameters
			[in]	p_instance	Pointer to the driver instance structure.
			[in]	timer_task	Timer task.
			Returns - Task address.
		(NRF_TIMER_TASK_COUNT = Task for incrementing the timer (in counter mode))
	*/
	uint32_t counter_addr_pixel = nrfx_timer_task_address_get(&counter_pixel, NRF_TIMER_TASK_COUNT);