LED Bar Graph Voltage Level Indicator With PIC18F4550

In the previous post, we show how to use ADC library function in CCS PICC. Here, the ADC is still in the discussion. In this example, I use almost the same source code, but one's difference is the output LED displays a bar graph pattern indicating the level of input voltage reading from the AN0.

x2

x1.5

x1

x0.5

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ADC result is still 8-bit. This 8-bit result is scaled into an 9 number values correspond to 8 output LEDs on PORTD.

LED bar graph running

Source code from GitHub gist.

	#include<18f4550.h>
	//Use High speed Crystal
	#fuses HS
	//Set the frequency for delay function
	#use delay(clock=20M)
	void main(void){
	unsigned int16 adcRead;
	char ledBar[9]={0x00,0x01,0x03,0x07,0x0F,0x1F,0x3F,0x7F,0xFF};
	//RA0 As Input
	set_tris_a(0x01);
	//PORTD as output
	set_tris_d(0x00);
	//Set RA0 To Analog
	setup_adc_ports(AN0);
	//Select ADC internal RC Clock
	setup_adc(ADC_CLOCK_INTERNAL);
	//Select channel 0 for conversion
	set_adc_channel(0);
	while(1){
	adcRead=read_adc();
	//Wait for completion
	while(!adc_done());
	adcRead=(adcRead*9)/256;
	//Output the result to PORTD
	output_D(ledBar[adcRead]);
	delay_ms(50);
	}
	}

view raw adc_barGraph.c hosted with ❤ by GitHub

Click here to download this example in zip file.

Schematic Diagram