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Altera_Forum
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12 years ago

Reading external data using On-chip FIFO and NIOS II

Hi all, I'm trying to read a 8-bit ADC with parallel output using NIOS II. I need to read the ADC at 24MHz to capture correct samples. I have been trying a 1K On-Chip FIFO to capture this data....
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Altera_Forum
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12 years ago

I have configured the FIFO this way: 

int init_input_fifo()
{
	int code = ALTERA_AVALON_FIFO_OK;
	code = altera_avalon_fifo_init(0x2001800, // Address
								   0x3F, 		   // Enable interrupts
								   1, 	   // Almost empty
								   1000); 	   // Almost full
	if (code == ALTERA_AVALON_FIFO_EVENT_CLEAR_ERROR)
		printf("A\n");
	else if (code == ALTERA_AVALON_FIFO_IENABLE_WRITE_ERROR)
		printf("B\n");
	else if (code == ALTERA_AVALON_FIFO_THRESHOLD_WRITE_ERROR)
		printf("C\n");
	//printf("CODE: %d\n", code);
	printf("ALMOSTEMPTY = %d\n", altera_avalon_fifo_read_almostempty(0x2001800));
	printf("ALMOSTFULL = %d\n", altera_avalon_fifo_read_almostfull(0x2001800));
	void* input_fifo_wrclk_irq_event_ptr = (void*) &input_fifo_wrclk_irq_event;
	alt_irq_register(16, input_fifo_wrclk_irq_event_ptr, handle_input_fifo_wrclk_interrupts);
	return code;
}

The ALMOSTEMPTY and ALMOSTFULL printed in the console are correct. My interrupt: 

static void handle_input_fifo_wrclk_interrupts(void* context, alt_u32 id)
{
	volatile int* input_fifo_wrclk_irq_event_ptr = (volatile int*) context;
	*input_fifo_wrclk_irq_event_ptr = altera_avalon_fifo_read_event(0x2001800, ALTERA_AVALON_FIFO_EVENT_ALL);
	altera_avalon_fifo_clear_event(0x2001800, ALTERA_AVALON_FIFO_EVENT_ALL);
	printf("INTERRUPT!!!");
}

Thanks