http://www.8051projects.net/ Learn to make simple microcontroller projects, pic, 8051, avr and arm projects. download 8051 projects, tutorials, libraries, sample codes. join the microcontroller discussion forum and ask doubts regarding electronics. the best source for 8051 over internet. en-gb 2009-01-07T17:30:56-08:00 contact@nospam.com hourly 1 2000-01-01T12:00+00:00 http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 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. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Ajay 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.. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Help 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. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Ajay well that is single-ended mux table... the datasheet i saw, have differential mux table too.. i send u the link... here.. Datasheet ADC08034hope 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..?? http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Help 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 http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Ajay 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 ADC08034where every bit of information is given. I hope that will help you http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Help 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 = 1SGL//DIF = 0ODD/SIGN = 0SELECT = 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. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Ajay 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 http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Help 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. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Ajay 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 http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Help Ya, thank you very much. You let me understand alot of thing. I also no plan to use ADC08034. Because i can't get this IC in my country and i think ADC0834 also mostly the same.I already order LT1787HV and LTC1286 will coming soon.Ya, may i know ADC can measure Negetive voltage and if negetive supply then how can i measure the current?Thank You. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Ajay well.. according the rule of electronics.. if the voltage is -ve then.. the current must be flowing in opposite direction.. so current measurement must be the same way.. just we get -ve value.. coz of opposite direction. maybe not sure.. i think there must be some provision to support -ve voltage in the IC.off-topic: where are you from by the way? http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 christie hi...I also doing the project about measure the current by using 8051 microcontroller but I have no ideas for design the circuit. Can u attach your circuit diagram for reference, please?Thanks http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Arun Kumar V Hello Christie,welcome to our forum !measuring Current using 8051 is simple, it is done same way as measuring voltage.first we need to convert the current flowing in the circuit to voltage, for that we use either : a sense (shunt) resistor,a non contact torridal transformer or a Current transformer (often called CT).for simple current measurements we can use Sense resistor of any value from 0.1 ohm to 1 ohm. now the sense resi has to be placed in the target circuit to read the current flowing, this resi can be placed in the negative path ( i,e between the load and ground) this is called as "low side sensing" and when we place the sense resi in positive path ( i,e between positive supply and load) this is called as "high side sensing"usually, low side sensing is easy and requires low components, so we'll stick to this type of current sensing for time being, the following figure shows this setup :now lets recollect our famous Ohm's law, V= RI , for eg : in the above circuit the sense resistor 's value is 1 ohm and when 1 ampere of current is flowing thru the circuit , then 1 Volt will be developed across the sense resistor. V = R x II = V / Rhere I = 1(volt) / 1(ohm) i,e = 1 (ampere)so we read this voltage developed across the sense resistor using a ADC and micro, this voltage signal can be fed to a Op-amp and then fed to a ADC to remove noise. the power dissipated in the Sense resistor needs to be calculated; its given by I2R ( here it is 1 watt, so to be on safe side we can use 5 watt wire wound 1 ohm resistor)for larger currents the sense resistor method does'nt work( becoz of large amounts of heat generated in resistor) , thats where we use CT or Torroid CT.Arun http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 pdi33 In industries, for high AC current measurement,C.T.s are used whereas for the high DC currents a DC shunt resistor is used. the shunt resistance is designed such that the output voltage from the shunt is always 75mV/150mV for full scale operating current.e.g. if u buy a 50A DC shunt, then the potential difference across the shunt when 50A is passed through it is 75/150mV . this DC voltage can then be given to a suitable op-amp amplifier to amplify the signal to the required level and given to the ADC as explained by arun. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 christie i have try to draw low side current sensing circuit but i cannot get the output in AC form.and i not sure that my output is correct or not. thanks http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Arun Kumar V Where is the load ? and what is the value of Sense resistor ?Arun http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 christie the load is R5 then the sense resistor is R4 n value is 1 ohm http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Arun Kumar V what do you call this connection ? ( i have marked ) high side or low side sensing ?pl.refer to the diagram i posted earlier and connect accordingly.Arun http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 nischay kumar @christie maybe you haven't noticed the "thanks" button in the posts, its there for some purpose, so use it for the people who are spending time to help you, our Moderators especially Mr.Arun has explained the concept in great detail and also Pdi33, so you owe them Big time.( i have seen in this forum, folks from Malaysia are seldom Thankful and very active in posting their problems) http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 ExperimenterUK Arun Kumar V wrote ...what do you call this connection ? ( i have marked ) high side or low side sensing ?I think it's "Other side sensing" To be fair it looks like a valid method,although the voltages marked are wrong.Your sense voltage should be more like 0.5 volts and the opposite polarity( I think ).>but i cannot get the output in AC form.Why do you want AC ?, it's a DC circuit, expect DC output Why are you using 50 Volts ?such a high voltage is likely to cause problems. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 pdi33 hi christie,ur ciruit looks perfectly o.k. except for the voltage levels ( just like experimenterUK said) and the output voltage u get would be of -ve polarity. Now this is not recommended as the op-amp is operating on a single +ve supply so u may possibly not get a valid -ve output on pin 6 of the op-amp. So i strongly suggest u interchange the Vin+ and Vin- inputs of the op-amp and generate a +ve DC signal at the output. http://www.8051projects.net/forum-t1037.html 2009-01-07T17:30:56-08:00 Arun Kumar V I think it's "Other side sensing" i used High side sensing and Low side sensing but "other side sensing" is new to me, LOLArun