DC METER USING MSP430F427

SUMAN BHARTI

Intellectual 555 points

Other Parts Discussed in Thread: MSP430F427, MSP430F427A, CD74HC4051

I want to make a DC meter, which can read DC Voltage and current, with MSP430F427.

Please tell me if it is possible, and if possible please provide details.

Thanks in advance.

over 9 years ago

0 Dennis Eichmann over 9 years ago

Guru 74080 points

Hi Suman!

Yes, in general you can do that with this device. But since it already has NRND-status, I would think about switching to the MSP430F427A device. Anyway - the processor has a built-in 16 bit ADC which can be used for your measurements. Depending on your plans regardning input range and resolution you will need to do some signal conditioning, so first you should think about your desired specifications.

Dennis

0 Dennis Eichmann over 9 years ago in reply to Dennis Eichmann

Guru 74080 points

You may want to look at this post:

Auto ranging - MSP low-power microcontroller forum - MSP low-power microcontrollers - TI E2E support...

e2e.ti.com

Other Parts Discussed in Thread: CD74HC4051 Consider a case if i want to measure the voltage at good resolution. But the ranges are different 2volts, 15volts,30volts

It describes a possible input resistor ladder for measuring different voltage levels.

Dennis

0 SUMAN BHARTI over 9 years ago in reply to Dennis Eichmann

Intellectual 555 points

Thanks for help Dennis,
My input range is between 0 to 100V and resolution needed is of 10mV.
Previously I have designed volt meter for AC current, but that do not read DC voltage accurately.
So, I need help in reading DC voltage.
Please help.

0 Ilmars over 9 years ago in reply to Dennis Eichmann

Guru 46710 points

Dennis, your divider have inherent flaw :) It basically have just 1:10 range unless relays are used.

Input of ADC or multiplexer CD74HC4051 will act as clamp for 1:10 tap, rendering higher ranges of your circuit useless at voltages exceeding 10*(VCC+V_clamp_diode_drop) volts.

0 Dennis Eichmann over 9 years ago in reply to Ilmars

Guru 74080 points

Ilmars, after a second thought about the analog multiplexer connected to the different taps I fully agree to your statement! You're right, the higher voltage taps will be clamped - thanks for pointing this out! I will have to correct that in the other post.

Dennis

0 SUMAN BHARTI over 9 years ago in reply to Dennis Eichmann

Intellectual 555 points

0 Dennis Eichmann over 9 years ago in reply to SUMAN BHARTI

Guru 74080 points

That is interesting since reading DC voltage is normally easier than AC. What are your thoughts on how to do it so far?

0 SUMAN BHARTI over 9 years ago in reply to Dennis Eichmann

Intellectual 555 points

Actually I want to read both AC & DC Voltage & Current Simultaneously, in same meter.
Please tell me if it is possible.

My meter reads 6-10 Volt less than actual, when used to measure from UPS. But on Mains it reads correct.
Please suggest solution.