req:8051 based volet and ampage meter

Why u asked for uc based voltagmeter and ammpermeter ?

there is a readymade ic available, ICL7107

it is easy to use for pcb and not have duael +/- supplies.

it wants 30v and 10 amps ranges. if u Have any ideia i will pls upload.
i want you to use it in my lab power supply.

The words are "voltmeter" and "ammeter"

You will get better search results by using the correct terms!

thanks ur reply MAX139 max139 is not avialable in my contory.and the price of ICL7107 is higher then AT89C51.

any one pls help me

plz

how much ammperage can i put to the port pin . and how much volterge can i pot to to port pin???? how can i use the resister and is 1mf good?????? how can i read ammperege and voltergd in float???? or do i use more pins????

plz answer now

From your questions it is obvious that you should park your project, and spend some time on genereral electronics.

You can not build a multimeter unless you either find a complete schematics + software + PCB or you aquire the knowledge about how they work.

You can't send any current into a processor pin. You use shunt resistors for that. Standard electronics knowledge tells how to compute resistances and required power specification - and how much the shunt resistor will heat up when measuring.

The data sheet for the processor specifies the voltage range for an ADC input, and if the processor has programmable gain and if it supports alternative voltage references.

I don't know what 1mf is. m = milli = 0,001. f = femto = 1E-15. Did you mean mF as in milli-farad? That is a capacitor and is only needed if filtering AC. Once more, computing low-pass filters requires electronics skills.

No normal ADC (any at all?) return any current or voltage as a float. They are linear or logarithmic and returns the measurement in a number of bits. You have to use basic programming skills to convert from the ADC value to the display value, taking into account the voltage reference, the full-range measurement value, any programmed gain, etc.

You use multiple processor pins if you want to measure multiple channels. But you don't use more pins to get a larger measurement range.

In short: Pick up a basic electronics handbook. Start studying. Only you can do the work needed for you to learn what to do, and why and how.

"how much ammperage can i put to the port pin."

The word is "current", and it will be specified in the Datasheet

"and how much volterge can i pot to to port pin?"

The word is "voltage", and it will also be specified in the Datasheet

"how can i use the resister"

The word is "resistor", and this is a basic application of Ohm's law.

"and is 1mf good"

It has no meaning in relation to a resistor!

If you mean 1mF or 1uF, that is 1 millifarad or one microfarad - which are measures of capacitance, not resistance

"how can i read ammperege and voltergd in float?"

You cannot do it directly - especially as you don't even seem to have understood the basic measurement principles yet!

You will need to use an Analogue-to-Digital Converter (or A/D Converter or ADC), with suitable input conditioning, and suitable code to handle its digital output.

"do i use more pins?"

You mean like using more question marks??????????

"the price of ICL7107 is higher then AT89C51."

But an AT89C51 cannot directly do what you require - only after you have put in a significant amount of work to make it do so!

If you can't and/or won't do the work yourself, then you have to pay for someone else to do it for you - eg, by buying a more expensive part that is ready-made for the application!

That's life.

i dinot want the lunch!!!!!!

his atertude is very bad and their is no manners!!!!

i read this and saw you,,,,

"you can take the camel to water but you can not stop the stink!"

"the price of ICL7107 is higher then AT89C51."

and what does that matter?

the issue of price is: the price of an ICL7107 vs the proce of an AT89C51 PLUS an A/D PLUS other external circuitry

Erik