16f88 - pin RA4 as analog input

[savnik]

ADCIN 4, adval 'Read channel 4 to adval
adval1 = adval*2/100
adval2 = adval*4//10
Lcdout "POWER: ", DEC2 adval1, ".", DEC1 adval2," WATT "

I have use this code and show ok

[sayzer]

I was going to ask how would you see say 2.30V, but Darrel already touched that point.

Now I wonder where did this "Watt" come from?

Lcdout "POWER: ", DEC2 adval1, ".", DEC1 adval2," WATT "

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[savnik]

Now I wonder where did this "Watt" come from?

I measure the RF of a FM linear with a wattmeter.The output is in volt.
This volt i want to measure , and show on LCD.

[sayzer]

Ok, that makes sense now.

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[Darrel Taylor]

ADCIN 4, adval 'Read channel 4 to adval
adval1 = adval*2/100
adval2 = adval*4//10
Lcdout "POWER: ", DEC2 adval1, ".", DEC1 adval2," WATT "

I don't think that's what you want.

Let's say that you have 4.8 V on the input. You'll get an A/D reading of 249.

249 * 2 / 100 = 4   This part is ok
249 * 4 = 996, and //10 gives 6
So that would display as 4.6 instead of 4.8

Or if you had 4.2 V, (214 A/D)

214 * 2 / 10 = 4   Still OK
214 * 4 = 856, and //10 gives 6
Still displays as 4.6 instead of 4.2

Here are some more results

Volts	A/D	Whole#	4*A/D	//10	Result
5.00	255	5	1020	0	5.0
4.90	249	4	996	6	4.6
4.85	247	4	988	8	4.8
4.80	244	4	976	6	4.6
4.75	242	4	968	8	4.8
4.70	239	4	956	6	4.6
4.65	237	4	948	8	4.8
4.60	234	4	936	6	4.6
4.55	232	4	928	8	4.8
4.50	229	4	916	6	4.6
4.40	224	4	896	6	4.6
4.30	219	4	876	6	4.6
4.20	214	4	856	6	4.6

I think you should take another look at the formulas in post #9

[savnik]

I don't think that's what you want.

Let's say that you have 4.8 V on the input. You'll get an A/D reading of 249.

249 * 2 / 100 = 4   This part is ok
249 * 4 = 996, and //10 gives 6
So that would display as 4.6 instead of 4.8

Or if you had 4.2 V, (214 A/D)

214 * 2 / 10 = 4   Still OK
214 * 4 = 856, and //10 gives 6
Still displays as 4.6 instead of 4.2

Here are some more results

Volts	A/D	Whole#	4*A/D	//10	Result
5.00	255	5	1020	0	5.0
4.90	249	4	996	6	4.6
4.85	247	4	988	8	4.8
4.80	244	4	976	6	4.6
4.75	242	4	968	8	4.8
4.70	239	4	956	6	4.6
4.65	237	4	948	8	4.8
4.60	234	4	936	6	4.6
4.55	232	4	928	8	4.8
4.50	229	4	916	6	4.6
4.40	224	4	896	6	4.6
4.30	219	4	876	6	4.6
4.20	214	4	856	6	4.6

I think you should take another look at the formulas in post #9

You are right , but I don't understand how to write the code for the remainder to show right the decimal

[Darrel Taylor]

[savnik]

Thank you