ATMEGA128 and DS2438 ?

[bianchi77]

Hello Guys,

Does anyone of you have experience with battery monitoring ?
Which one is good for monitoring 12V battery ?
I saw DS248....what do you reckon ?

I want to monitor my battery with it and display the voltage status on LCD..

Any clues will be very appreciated,

Thank you

 

[tpetar]

No need for special IC, just use uC ADC with voltage divider.

If you plan to monitor remote battery over 1-wire then use 1-wire IC.



Best regards,
Peter

 

[bianchi77]

No need for special IC, just use uC ADC with voltage divider.

If you plan to monitor remote battery over 1-wire then use 1-wire IC.



Best regards,
Peter

That's good idea any circuit and code example ?

 

[tpetar]

That's good idea any circuit and code example ?

Nothing special, you can find tons of examples on EDABoard for this. See examples in my blog (ADC:0-5V Input:0-20V). Just use voltage divider with adequate resistors, put one capacitor for averaging and zener 5,1V for ADC protection. You can even log that value periodically in EEPROM.


Best regards,
Peter

 

[bianchi77]

I can't see op amp circuit on it ? can you show me ? is it comparator ?
thanks

 

[tpetar]

I can't see op amp circuit on it ? can you show me ? is it comparator ?
thanks

There is no need for OpAmp. Just use voltage divider for lets say up to 20V.



Best regards,
Peter

 

[bianchi77]

**broken link removed**
Like above ? what's the resistor value for it ?

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http://www.calculatoredge.com/electronics/voltage%20divide.htm ??

 

[tpetar]

Voltage divider calculator :
https://www.electronics2000.co.uk/calc/potential-divider-calculator.php


Use calculator to have max 5V on output.

Use higher value for R1 such as 47KΩ.

After voltage divider, add 1uF capacitor and zener 5,1V.




Best regards,
Peter

 

[bianchi77]

is it enough with 1/4 W resistor for it ?

 

[tpetar]

Yes its ok. I use 1206 or 0805 resistors.

R2 can be small trimmer.



Best regards,
Peter

 

[bianchi77]

Ok, thank you my friend, I'll make experiment for it and get back to you....

 

[tpetar]

Ok, thank you my friend, I'll make experiment for it and get back to you....

Ok I'm here.

Use 12V-20V-30V input voltage and measure voltage on output with voltmeter.

Try R1 47K and R2 10K trimmer.



Best regards,
Peter

 

[bianchi77]

On Vout I connect ZD and caps as a filter and limiter ?

 

[tpetar]

Yes capacitor is for averaging and zener 5,1V is to protect uC ADC.


Best regards,
Peter

 

[bianchi77]

Hi Peter is the circuit like this ?

thanks

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I make 1:4.7 divider...

 

[jayanth.devarayanadurga]

In your Blog you have posted images of Blue LCD. In which simulator you got the Blue LCD?

 

[tpetar]

Yes, try to play with resistor calculation or try with small trimmer.

This ensures input voltages in 0-5V range, and in my blog you can find various codes for this in MikroC.

Use OpAmp if you have small voltage on input, such as voltage drop on current shunt resistor, and appropriate circuit to make 0-5V voltage for ADC.

Zener diode is safety for ADC pin.

For 20V try for R1 3,9K and for R2 1,3K.

You can play with voltage divider and OpAmp without ADC and uC, just use voltmeter, when you define configuration use on uC ADC.

In your Blog you have posted images of Blue LCD. In which simulator you got the Blue LCD?

Its LCD Screenshot Generator, you can download from here:

https://avtanski.net/projects/lcd/

Its fast and usefull for documenting code or project.




Best regards,
Peter

 

[bianchi77]

do you have example code for avr ? I want to use ADC1 on ATMEGA128

 

[jayanth.devarayanadurga]

Which Compiler do you use? Atmel Studio or mikroC AVR PRO? I can give you code which is for mikroC PRO AVR Compiler.

 

[bianchi77]

I created like this :

uint16_t read_adc1(void)
{
	ADMUX=(1<<REFS0) | (1<<ADLAR) | ADC_1;    // Conversion on channel 1, AVCC reference, 10 bit mode
	ADCSRA |= (1<<ADSC);                     // Start conversion
	loop_until_bit_is_clear (ADCSRA, ADSC);         // Wait for conversion complete
	return(ADCH);
}

I want to measure the voltage from channel 1 of ADC on ATMEGA128

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Which Compiler do you use? Atmel Studio or mikroC AVR PRO? I can give you code which is for mikroC PRO AVR Compiler.

I use Atmel Studio

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I've done :

void adc_init()
{
	// enable ADC, select ADC clock = F_CPU / 128 (i.e. 125 kHz)

	ADCSRA = (1<<ADEN | 1<<ADPS2 | 1<<ADPS1 | 1<<ADPS0 );

	//Do a conversion to get rid of rubbish

	ADMUX=(1<<REFS0 | ADC_0);                  //Conversion on channel 0, thermistor input
	//Internal VCC Voltage Reference
	ADMUX=(1<<REFS0 | ADC_1);                  //Conversion on channel 0, thermistor input
	//Internal VCC Voltage Reference

	ADCSRA |= (1<<ADSC);                      //Start conversion
	loop_until_bit_is_clear(ADCSRA, ADSC);    //Wait for conversion complete
}


uint16_t read_adc1(void)
{
	ADMUX=(1<<REFS0) | (1<<ADLAR) | ADC_1;    // Conversion on channel 1, AVCC reference, 10 bit mode
	ADCSRA |= (1<<ADSC);                     // Start conversion
	loop_until_bit_is_clear (ADCSRA, ADSC);         // Wait for conversion complete
	return(ADCH);
}

double resistor_get_voltage(long adcresistence)
{
	
	double t;
	t = log( adcresistence );
	return t;
}

	adc_result=read_adc1(); //read the voltage from ADC1
		adcA = ((int)(adc_result*5.0)/1024.0)*1000; 
		d = resistor_get_voltage(adcA);

		
		if (adcA != 0)
		{
			adcresistance = (long)(10230000/adc_result-10000);	
			sprintf(voltage,"%.2f",d);
			lcd_string(voltage);
		}

Please correct me if I missed something here,
thanks