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How to measure current? (ADC08034 interface to the AT89C52)

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Help

Fri Jun 15 2007, 09:40PM

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Hi,

Anyone use ADC08034 before?

How can i measure current? I found one application from ADC08034 datasheet which i think can measure the current? But then I'm confusing the Digitizing a Current Flow Application show in datasheet page-17. ADC08034 don't had Vin(-) and Vout(+) pin. I wondered why this application using 08034. If we try to use ADC08031 for this application but this IC miss one pin function which is VrefOut.

What can i do? or got other option for me to measure current? Please anyone can help me?

Thank You.

ADC08034 Digitizing a Current Flow Application of ADC08034 measure current using ADC08034 ADC08034 interface to the AT89C52 analog to digital converter

Ajay

Sat Jun 16 2007, 01:27AM

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i think you did not see the datasheet carefull

see page 12, Differential Mux Mode of ADC08034. There its explained how the four channels can be used for V(+) and V(-).
please correct me if i am worng..

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Sat Jun 16 2007, 03:03AM

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emm...I'm not sure, the Table-4 MUX Addressing:ADC08034 no show the "-" in table. It just have "+".

Ya, I would like to share with you that I found a great ADC which we can scale up to 100A, we can use very least pin interface with uC and EASILY to control. Try to search LT1787HV and LTC1286 chip.

Please give some comment...

Thank You.

[ Edited Sat Jun 16 2007, 03:06AM ]

ADC LT1787HV ADC LTC1286 analog to digital converter

Ajay

Sat Jun 16 2007, 03:46AM

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well that is single-ended mux table... the datasheet i saw, have differential mux table too.. i send u the link... here.. Datasheet ADC08034
hope this will help you.
i mean.. just below the single-ended MUX table there is differential mux table too.. check it..
and i will look for these ICs u told. well just thinkin are they able to hold this much of current..??

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Sat Jun 16 2007, 08:07AM

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Hi,

Thank for you datasheet. Ya, youres one is different with my.

I already write the code to control ADC08034 but it's not work.. I use Proteus 6.9sp5 to simulate it. Please can you help me to check?

I'm not sure it will work so high Amp not...normaly IC can handle high current will need heat sink. Somemore the input can reach 60V!!
I plan to buy the tht IC for testing. Don't know this IC hard to buy not. Hope i can buy it. I will let you know the result.

1182006464_880_FT1037_adc08034.zip

[ Edited Sat Jun 16 2007, 08:08AM ]

Ajay

Sat Jun 16 2007, 08:44AM

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Well i am sorry to say but your program is totally wrong. The thing is you simply wrote the program without understanding how the ADC is working.
In your data_in routine you are not storing the data anywhere...
and in your data_out routine you are not setting up the ADC to tell how suppose to work. i mean, first you need to configure the ADC, setting up the MUX etc.
For programming help i suggest you to read Page 8 timing diagram for ADC08034
where every bit of information is given. I hope that will help you

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Sat Jun 16 2007, 09:15PM

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Sorry, i think my function name comfused you.

The function ADC_Data_In is for configure the ADC. I got configurate the ADC which i define DATAIN 0x01 and transmit to ADC because i'm follow the Differential-MUX-Mode:
START = 1
SGL//DIF = 0
ODD/SIGN = 0
SELECT = 0
This setting is to configurated the Chn0 = V+ and Chn1 = V-

The ADC_Data_Out is for storing the data into the DATA[] array when the ADC transmited the bit.

May i know the SARS data is generated by ADC?
I try to play around the SARS on simulation, wait the SARS goes Hi after 4-bit DI but this bit wounldn't rising up. Why?

I'm using the Proteus to simulate the result. The result quite similar with the Timing-diagram.

Ajay

Sun Jun 17 2007, 11:39AM

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hi buddy, sorry for late reply.. coz sunday.. was out..

anyways.. so regarding this.. mm.. i think.. you are not doing the things correctly..
so.. is this way..
first four bits are sent on the rising edge.. and the falling edge at the time of fourth bit, the SARS will go high, what you have to do after that is, keep sending the clock and the first MSB is received at that time, and after 8 clocks, SARS will become low, so the next byte will be your LSB and LSBit is sent first second time.
and... you have to take care of chip select signal, as soon as you make it high, the data becomes invalid and.. start of conversion is made with the help of this chip select signal i.e. as soon as you make it low the conversion starts.
so you have to read the data before making next conversion, and to make the next conversion, you have to make CS HI->LOW

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Wed Jun 20 2007, 03:52AM

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Hi fren..
Don't worry is ok.

we should enjoy our weekend. 1st i have to say thank for helping me. Thank You.

This few days i already tested and found out one thing. I just realize if Pick-Devices preview show "No Simulator Model" in Pretues mean we can't simulate that device(ADC08034).
So, I try to use ADC0834 to simulate and follow your instruction. I think it working fine already.

May i know Vin(+) Trimport and the 1k FS Trimport is for what perpose? There is no different if i adjust them.
Another question is the SARS pin is just for us to view and know the ADC status (like setting MUX, MSB, LSB), we can't connect to our uC one rite? because when i connected to uC will "Simulation Log" message.
Last question, why my Proteus will comeout "Simulation Log" the message say that "Simulation is not running in real time due to exessive CPU load." do you know why?

Thank You.

Ajay

Wed Jun 20 2007, 05:59AM

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yes one thing is sure that you cannot simulate ADC08034. also in your schematic the option "exclude from simulation" is checked. i think it is done automatically. if the IC doesn't have a simulator model.

Now regarding SARS, i think.. its for those IC where the receiving is done on interrupt basis.. i think.. so that CPU comes to know that next byte is going to come.
Vin(+) is one of the i/p of the differential operation of the ADC. and the use of 1K trimmer is... maybe to set the zero op if the i/p are same.. its used for the voltage adjustment i think. nothing much.
i donno the answer i gave is exactly what u wanted... or your doubt was.. but.. i tried my best.. to satisfy you.. coz before this i never used ADC08034

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