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> ... the capacitor (I have been connecting my voltmeter though)... Though or through? You don't really mean through, do you? If you've had the capacitor in series with the DVM, you'll show an average zero volts - and lots of noise and varations on the DVM - no matter what you try with the resistor or with your code. You must connect the resistor between the D/A pin and one end of the capacitor (which must be the positive terminal if it's an electrolytic or tantalum) with the other capacitor terminal to ground. Read the voltage across the capacitor, i.e. connect the DVM to the junction of the resistor and the capacitor, and ground. Tom Becker --... ...-- www.RighTime.com The RighTime Clock Company, Inc., Cape Coral, Florida USA +1239 540 5700 |
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Re: PutDAC - strange voltages
Started by ●October 14, 2003
Reply by ●October 21, 20032003-10-21
Reply by ●October 21, 20032003-10-21
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Yes, I checked my grounding! Best regards Sebastian Probst Eide Web: <http://dagensstart.com/> Dagensstart.com Email: <mailto:> Phone: +47 9797 0000 -----Original Message----- From: Bob Dyer [mailto:] Sent: 17. oktober 2003 23:42 To: Subject: RE: [BasicX] PutDAC - strange voltages :( Sebastian, Did you ever do as Neil suggested and check your Grounding? Bob -----Original Message----- From: Sebastian P. E. Any thing that could solve the problem and give me the correct voltages at up to 5V would be great! -----Original Message----- From: Neil Jepsen Make sure the ground on BOTH boards are joined together. <http://rd.yahoo.com/M%1812.4052765.5265175.1261774/D=egroupweb/S06 554205:HM/A54451/R=0/SIGtfoi6qi/*http:/www.netflix.com/Default?mqs o`178323&partid@52765> click here <http://us.adserver.yahoo.com/l?M%1812.4052765.5265175.1261774/D=egrou pmail/S=:HM/A54451/randq6833660> ">http://docs.yahoo.com/info/terms/> Service. |
Reply by ●October 21, 20032003-10-21
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I’ll try calling it more often... But the results I got where with a
modified program calling the PutDAC every 10 milliseconds… but I still
didn’t get voltages above 1V… Best regards Sebastian Probst Eide Web: <http://dagensstart.com/> Dagensstart.com Email: <mailto:> Phone: +47 9797 0000 -----Original Message----- From: Chris [mailto:] Sent: 17. oktober 2003 20:23 To: Subject: Re: [BasicX] PutDAC - strange voltages :( Sebastian, You need to call PutDac every 5-20 milliseconds to maintain the voltage. In your old program it looked like you only called it every 2 seconds. Chris ----- Original Message ----- From: "Sebastian P. E." <> To: <> Sent: Saturday, October 18, 2003 11:07 AM Subject: RE: [BasicX] PutDAC - strange voltages :( I finally got my hands on a couple of .1uF caps, but the results are still not as good as they should be! With a .1uF I get voltages between 0.2 and 0.8V while I with a 0.01uF get voltages at around 0.1-0.5V. With a 10uF I get voltages at about 0.20-0.35V… Any thing that could solve the problem and give me the correct voltages at up to 5V would be great! Best regards Sebastian Probst Eide -----Original Message----- From: Neil Jepsen [mailto:] Sent: 16. oktober 2003 04:28 To: Subject: Re: [BasicX] PutDAC - strange voltages :( Make sure the ground on BOTH boards are joined together. Sebastian P. E. wrote: > I am sorry that I am bothering you with this boring problem, but I > really have to get this to work... Please keep on being patient with me > and the mistakes I might make, I a newbie... > > I just tested a couple of things on my two development boards and got > some strange results which kind of made it no wonder that I got strange > voltage results on my earlier tests. I can't see why I get the results > though... > > I have got two separately powered development boards, a dev board for > the basicX chip, and a normal solderless breadboard. > > When I measure the voltage between the: > -5+ and the gnd on the dev board I get: 4.98V > -Positive pole on the solderless board and the negative gnd on the > s.board I get: 6.06V (That is correct!) > -Positive pole on the s.board and gnd on the dev board while the chip is > in the dev board, I get: 0V (Should have been 6.06V as with the gnd on > the s.board!) > -5+ on the dev board and the gnd on the solderless board I get: 0.28V > (should have been 4.98V!) > -gnd on the dev board and the gnd on the s.board I get: -0.38V! (should > have been 0.0V!!) > -PIN 13 while on dev board and gnd on dev board I get: 0.38V > -Capacitor connected to the low pass circuit connected to PIN 13 and gnd > on dev board I get: 0.38V > -Capacitor connected to the low pass circuit connected to PIN 13 and gnd > on s.board I get: 0.00V > I am including the program just in case you want to see it, I can't see > why the error should be in the coding though, but just in case. > The circuit I am using is still exactly the one shown me earlier by > Chris: > > 1K > BX-Pin o-----/\/\/\/\/\---o----o DAC Out > | > | > ____ > ____ .1uF cap > | > | > ------ > --- > - Ground > > > Here is the code on the chip: > What it does is sending a voltage for 8 seconds before it is starting to > send another voltage. > The red LED is blinking at different speeds for the different voltages > to indicate the state of the program. > First it is sending a nondimvolt of 0.2, then 0.4, then 0.6, then 0.8 > and at last 1.0 before it is starting at 0.2 again. > > I am sorry that I wrote the comments in Norwegian, but I originally had > no intentions posting the code to this forum. > Option Explicit > 'Dette er først og fremst et lite program som jeg skal bruke for > 'å se hvor mye strøm denne saken pøser ut... > > '************************************************ > 'Variabler jeg kommer til å trenge gjennom programmet > dim bLys as boolean > const nLys as byte = 25 > const voltagePin as byte = 13 > dim voltage13counter as byte > Dim Teller as byte > Dim NonDimVolt as byte > Dim LysTaskStack(1 to 32) as byte > Const MaksRunder as byte = 4 > > '************************************************ > 'Hoveddelen > Public Sub Main() > > 'Kaller startfunksjonen > Call Init() > > Debug.Print "Programmet kjører" > bLysse > > '*********************** > CallTask "lysTask", lysTaskStack > > '*********************** > Do > If teller=MaksRunder then > Teller=0 > > If NonDimVolt <> 5 then > NonDimVolt=NonDimVolt+1 > Else > NonDimVolt=1 > End if > > End if > > Debug.Print "Setter voltage. "; > Debug.Print "NonDimVolt er "; cstr(NonDimVolt); > Debug.Print ". Sove: "; cstr((csng(NonDimVolt))*0.1); > 'Stygg løsning, men det andre fungerte jo ikke... > Select Case NonDimVolt > Case 1 > Debug.Print " ---- Case 1" > Call PutDAC(voltagePin, 0.2, voltage13counter) > Case 2 > Debug.Print " ---- Case 2" > Call PutDAC(voltagePin, 0.4, voltage13counter) > Case 3 > Debug.Print " ---- Case 3" > Call PutDAC(voltagePin, 0.6, voltage13counter) > Case 4 > Debug.Print " ---- Case 4" > Call PutDAC(voltagePin, 0.8, voltage13counter) > Case 5 > Debug.Print " ---- Case 5" > Call PutDAC(voltagePin, 1.0, voltage13counter) > End select > > Call Sleep (2.0) > Teller=Teller+1 > Loop > > End Sub > > '************************************************ > Sub Init() > 'Dette er en sak som setter variablene slik jeg vil ha dem > Teller = 0 > NonDimVolt=1 > > 'Bekrefter at funksjonen har vært kjørt... > Debug.Print "Init kjørt." > End Sub > > '************************************************ > Sub lysTask() > > Do > > If bLys then > Call PutPin(nLys,0) > Else > Call PutPin(nLys,1) > End if > > bLys = Not bLys > > Call Sleep((csng(NonDimVolt))*0.1) > Loop > > end sub > Best regards > Sebastian Probst Eide > > -----Original Message----- > From: Sebastian P. E. [mailto:] > Sent: 16. oktober 2003 20:06 > To: > Subject: RE: [BasicX] PutDAC - strange voltages :( > > Well... this is really weird... > I put the BX-24 chip on my solder less breadboard and made the red LED > blink every time the PutDAC command was called so I would know if the > chip really was turned on. The program was the same I used when testing > on the dev board shipped with the chip. The LED started blinking as it > was supposed to, but there was no output at pin 13 although there had > been one while the chip was on the dev board. I even tried connecting a > wire directly to the pin to make sure there was a connection. I didn't > even get the strange voltages I previously complained about; I just got > a blank 0. > > If any of you guys has any idea what I might be doing wrong, please let > me know. I'll prototype a bit more in the meantime. > > I went over all the different connections on the board multiple times to > ensure I hadn't done anything wrong. > When the voltage was tested against the positive connection spot on the > board it showed the input voltage of the board, and when connected to > the negative spot it just showed 0. > > Best regards > Sebastian Probst Eide > > -----Original Message----- > From: Sebastian P. E. [mailto:] > Sent: 16. oktober 2003 19:24 > To: > Subject: RE: [BasicX] PutDAC - strange voltages :( > > Hi again Chris and everybody else reading this post. > I built a low pass filter as you described below but I still get strange > voltages. > I used a 1K resistor and connected it to a cap. which was connected to > ground. I measured the voltage at the resistor capacitor junction as > you told me to. > I tried with two different nondimVolt values: 0.2 and 1.0, but they both > returned a voltage of 0.48V. :-( > > The capacitors I tried, the only ones I could get here in Norway today, > had the following values: 47u and 220u > > Any ideas what could be wrong? > > Best regards > Sebastian Probst Eide > -----Original Message----- > From: Chris [mailto:] > Sent: 14. oktober 2003 19:33 > To: > Subject: Re: [BasicX] PutDAC - strange voltages > > Did you use an RC filter on the Dac pin? > > Try this circuit: > > 1K > BX-Pin o-----/\/\/\/\/\---o----o DAC Out > | > | > ____ > ____ .1uF cap > | > | > ------ > --- > - Ground > > Hopefully if my tabs aren't cut off you will see the circuit. > You connect a 1K resistor to your BX i/o pin, the other > end of the resistor is connected to a .1uF cap to ground. > The smoothed analog voltage is present at the resistor > capacitor junction. > > Chris > > > ----- Original Message ----- > From: "Sebastian P. E." <> > To: <> > Sent: Saturday, October 18, 2003 10:11 AM > Subject: [BasicX] PutDAC - strange voltages > > Hi > > I just tried the PutDAC command for the first time. > > I set up 6 pins to deliver different voltages from 1 to 5V but didn't > > really get the results I had expected. > > The actual voltages are listed below: > > > > PIN Number, NondimVolt, Actual voltage Should have been > > 13 0.2 0.23V 1.0V > > 14 0.4 0.24V 2.0V > > 15 0.5 0.19V 2.5V > > 16 0.6 0.35V 3.0V > > 17 0.8 0.15V 4.0V > > 18 1.0 0.17V 5.0V > > > > This shouldn't be the case though according to the documentation which > > states that a nondimvoltage of 1.0 should give the pin an output of > 5V! > > I continuously refreshed the states of the 6 different pins just to > make > > sure the voltage stayed the same. > > > > Another weird thing is that my multimeter wouldn't measure the voltage > > if I didn't use the ground on the developer board. I tried with a > > different ground supplied by another power source as well, but it > didn't > > give me any results at all! Any reason why this shouldn't work? > > > > Best regards > > Sebastian Probst Eide > > > > > > > > > > > > > > > > > > > > ">http://docs.yahoo.com/info/terms/ > > > > > > > > > > <http://rd.yahoo.com/M%1812.4024216.5238180.1261774/D=egroupweb/S06 > 554205:HM/A54451/R=0/SIGtmlldst/*http:/www.netflix.com/Default?mqs > o`178323&partid@24216> click here > <http://us.adserver.yahoo.com/l?M%1812.4024216.5238180.1261774/D=egrou > pmail/S=:HM/A54451/rand72211947> > > ">http://docs.yahoo.com/info/terms/> Service. > > > <http://rd.yahoo.com/M$4522.3707890.4968055.1261774/D=egroupweb/S06 > 554205:HM/A95056/R=0/SIG4p07ne0/*http:/ashnin.com/clk/muryutaitake > nattogyo?YH707890&yhad95056> Click Here! > <http://us.adserver.yahoo.com/l?M$4522.3707890.4968055.1261774/D=egrou > pmail/S=:HM/A95056/rand5126111> > > ">http://docs.yahoo.com/info/terms/> Service. > > > <http://rd.yahoo.com/M$4522.3707890.4968055.1261774/D=egroupweb/S06 > 554205:HM/A95055/R=0/SIG4j83ehr/*http:/ashnin.com/clk/muryutaitake > nattogyo?YH707890&yhad95055> Click Here! > <http://us.adserver.yahoo.com/l?M$4522.3707890.4968055.1261774/D=egrou > pmail/S=:HM/A95055/randS9757973> > > ">http://docs.yahoo.com/info/terms/> Service. > <http://rd.yahoo.com/M$4522.3707890.4968055.1261774/D=egroupweb/S065542 05:HM/A95055/R=0/SIG4j83ehr/*http:/ashnin.com/clk/muryutaitakenattogyo ?YH707890&yhad95055> Click Here! <http://us.adserver.yahoo.com/l?M$4522.3707890.4968055.1261774/D=egroupmai l/S=:HM/A95055/rande3702444> ">http://docs.yahoo.com/info/terms/> Service. ">http://docs.yahoo.com/info/terms/ <http://rd.yahoo.com/M$4522.3707890.4968055.1261774/D=egroupweb/S06554205:HM/A95053/R=0/SIG4gf29oe/*http:/ashnin.com/clk/muryutaitakenattogyo?YH707890&yhad95053> Click Here! <http://us.adserver.yahoo.com/l?M$4522.3707890.4968055.1261774/D=egroupmail/S=:HM/A95053/rand3026183> ">http://docs.yahoo.com/info/terms/> Service. |
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Reply by ●October 21, 20032003-10-21
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I meant "though" not "through"... My low pass filter is as you described. Best regards Sebastian Probst Eide --- In , "Tom Becker" <gtbecker@r...> wrote: > > ... the capacitor (I have been connecting my voltmeter though)... > > Though or through? > > You don't really mean through, do you? If you've had the capacitor in > series with the DVM, you'll show an average zero volts - and lots of noise > and varations on the DVM - no matter what you try with the resistor or with > your code. > > You must connect the resistor between the D/A pin and one end of the > capacitor (which must be the positive terminal if it's an electrolytic or > tantalum) with the other capacitor terminal to ground. Read the voltage > across the capacitor, i.e. connect the DVM to the junction of the resistor > and the capacitor, and ground. > Tom Becker > --... ...-- > GTBecker@R... GTBecker@S... www.RighTime.com > The RighTime Clock Company, Inc., Cape Coral, Florida USA > +1239 540 5700 |
Reply by ●October 21, 20032003-10-21
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Sebastian Whenever you are using more than one power supply, in most cases ( nost not all) you must connect the grounds together. I can't think of an instance except perhaps where you are using opto isolators, where this would not be the case. Your WIMA 0.1 is OK, but I'm surprised that the 10k didn't work,. this points to your DVM being low impedance. I just hooked up a BX24 as follows: Pin 12 had a 10k in series with a 0.1 to ground. I used a Fluke DVM Program was : '****************************** public sub main() dim daccounter as byte do call putdac(12,0.5,daccounter) loop end sub '******************************* The values I got were:- nondimvolt: measured value: 0.25 1.3 volts 0.5 2.4v 0.75 3.5v 1.0 4.6v Sebastian P. E. wrote: Neil, I tried connecting the two grounds a week ago as I received your post, and the results posted earlier this day where from that test, but the voltages where still wrong so I didn't see any reason posting them till Tom asked me if I actually had tried your advice. 1. I have never been connecting anything else to the pin except the resistor (I have both tried a 1k (998ohm) and a 10k (9880ohm). I got shitty results with the 10k resistor) and the capacitor (I have been connecting my voltmeter though). I haven't even been using any of the other pins at the same time. 2. The capacitors I have been using at my latest test have all been in the range between 0.01 and 0.1uF. I have tried connecting them back to front as well but they always deliver the same result. Is there a way to determine whether a cap is electrolytic or not? I just grabbed some parts from a box at my school and there is no documentation at all and the inscriptions do not tell me much except the capacity. (On one: 0.1 | 63- A | S 2 | WIMA, on the other type: 0.01 | 100-A | WIMA | T21). I haven't been able to find capacitors in any electronics store here in Norway so far, believe me, I have tried several. and if the ones I have got aren't electrolytic should work fine, shouldn't they? That is if they're not really old which I hope they're not. 3. I have got a brand new digital multimeter. It is called CM2701 and was made by Caltek instruments. I have been using it set to measure DC volts. 4. I tried refreshing the pin every 1 milliseconds and every 0.1 milliseconds but the results stayed the same. 5. I tried pin 13, 14 and 15, all with the same results. Now I get a voltage at up to 2.73V though! Hip hurray! Not quite 5V though. Best regards Sebastian Probst Eide -----Original Message----- From: Neil Jepsen [mailto:] Sent: 21. oktober 2003 08:24 To: Subject: Re: [BasicX] PutDAC - strange voltages :( Sebastian...I told you about connecting the grounds together a week ago!! I would do the following: 1. Disconnect EVERYTHING from the pin you are testing, EXCEPT the resistor and the capacitor. 2. The capacitor must be a non electrolytic and between 0.01 and 0.47 uF. The reason I say this is an electrolytic can be connected back to front, or or might be leaky. If you use a mylar or similar, it can't be connected wrongly. 3. You must use a digital voltmeter. Grand-dad's old analogue VOM probably has a low input impedance. What meter are you using? Make sure the meter is set to DC volts. 4. Refresh the pin as fast as you can 5. If this doesn't work, try one of the other output pins. You may have damaged a pin. 5. Tell us what you get when you've done ALL of this. neil Sebastian P. E. wrote: > Do not misunderstand me. My readings are NOT good, just that the > hardware problem isn't much of a problem any more! That single problem > is gone. The strange voltages from the chip are still the same! > > Best regards > Sebastian Probst Eide > Web: <http://dagensstart.com/> Dagensstart.com > Email: <mailto:> > Phone: +47 9797 0000 > > -----Original Message----- > From: Sebastian P. E. [mailto:] > Sent: 22. oktober 2003 07:20 > To: > Subject: RE: [BasicX] PutDAC - strange voltages :( > > Hi Tom. > After I connected ground on the two boards the problem disappeared. > My readings are now good: > > GRN - GRN : 0V > 5V strip on dev board and: > -GND on dev board: 4.98V > -GND on s.board: 4.98V (obviously) > Positive strip on the s.board and > -GND on dev board: 6.06V > -GND on s.board: 6.06V (obviously) > -5V strip on dev board: 1.08V > Directly connected to PIN13 and GRN: 0.00-0.10V > Directly connected to PIN13 and GRN through a low pass filter: 0.20-1.0V > (depending on the different nondimVolt values (The PutDAC is called once > every 5 milliseconds)) > > Best regards > Sebastian Probst Eide > -----Original Message----- > From: Tom Becker [mailto:] > Sent: 21. oktober 2003 04:51 > To: > Subject: RE: [BasicX] PutDAC - strange voltages :( > > Before you worry about code and low-pass filters, you need to solve the > hardware problems that you listed in a previous message: > > > Positive pole on the s.board and gnd on the dev board while the chip > is in the dev board, I get: 0V (Should have been 6.06V as with the gnd > on the s.board!) > > +5 on the dev board and the gnd on the solderless board I get: 0.28V > (should have been 4.98V!) > > gnd on the dev board and the gnd on the s.board I get: -0.38V! (should > have been 0.0V!!) > > Until these are what they should and must be, you should defer more > complex notions. > Tom Becker > --... ...-- > www.RighTime.com > The RighTime Clock Company, Inc., Cape Coral, Florida USA > +1239 540 5700 <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 > 554205:HM/A32163/R=0/SIGn0nglqg/*http:/www.ediets.com/start.cfm?co > de0510&media=zone> click here > <http://us.adserver.yahoo.com/l?M4081.4074964.5287182.1261774/D=egrou > pmail/S=:HM/A32163/rand75382935> > > ">http://docs.yahoo.com/info/terms/> Yahoo! Terms of Service. <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 > 554205:HM/A06996/R=0/SIGp5b9ris/*http:/www.ediets.com/start.cfm?co > de0509&media=atkins> click here > <http://us.adserver.yahoo.com/l?M4081.4074964.5287182.1261774/D=egrou > pmail/S=:HM/A06996/randb8306793> > > ">http://docs.yahoo.com/info/terms/> Service. > > <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 554205:HM/A06996/R=0/SIGp5b9ris/*http://www.ediets.com/start.cfm?c ode0509 <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 554205:HM/A06996/R=0/SIGp5b9ris/*http:/www.ediets.com/start.cfm?co de0509&media=atkins> &media=atkins> > ">http://docs.yahoo.com/info/terms/>. <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 554205:HM/A32163/R=0/SIGn0nglqg/*http:/www.ediets.com/start.cfm?co de0510&media=zone> click here <http://us.adserver.yahoo.com/l?M4081.4074964.5287182.1261774/D=egrou pmail/S=:HM/A32163/rand67302747> ">http://docs.yahoo.com/info/terms/> Service. <http://www.ediets.com/start.cfm?code0509&media=atkins" target="_blank" rel="nofollow">http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06554205:HM/A32161/R=0/SIGp5b9ris/*http://www.ediets.com/start.cfm?code0509&media=atkins Your use Sebastian P. E. wrote: > Neil, I tried connecting the two grounds a week ago as I received your > post, and the results posted earlier this day where from that test, but > the voltages where still wrong so I didn't see any reason posting them > till Tom asked me if I actually had tried your advice. > > 1. I have never been connecting anything else to the pin except the > resistor (I have both tried a 1k (998ohm) and a 10k (9880ohm). I got > shitty results with the 10k resistor) and the capacitor (I have been > connecting my voltmeter though). I haven't even been using any of the > other pins at the same time. > 2. The capacitors I have been using at my latest test have all been > in the range between 0.01 and 0.1uF. I have tried connecting them back > to front as well but they always deliver the same result. Is there a > way to determine whether a cap is electrolytic or not? I just grabbed > some parts from a box at my school and there is no documentation at all > and the inscriptions do not tell me much except the capacity. (On one: > 0.1 | 63- A | S 2 | WIMA, on the other type: 0.01 | 100-A | WIMA | T21). > I haven't been able to find capacitors in any electronics store here in > Norway so far, believe me, I have tried several. and if the ones I have > got aren't electrolytic should work fine, shouldn't they? That is if > they're not really old which I hope they're not. > 3. I have got a brand new digital multimeter. It is called CM2701 > and was made by Caltek instruments. I have been using it set to measure > DC volts. > 4. I tried refreshing the pin every 1 milliseconds and every 0.1 > milliseconds but the results stayed the same. > 5. I tried pin 13, 14 and 15, all with the same results. Now I get > a voltage at up to 2.73V though! Hip hurray! Not quite 5V though. > > Best regards > Sebastian Probst Eide > -----Original Message----- > From: Neil Jepsen [mailto:] > Sent: 21. oktober 2003 08:24 > To: > Subject: Re: [BasicX] PutDAC - strange voltages :( > > Sebastian...I told you about connecting the grounds together a week > ago!! > > I would do the following: > 1. Disconnect EVERYTHING from the pin you are testing, EXCEPT the > resistor and the capacitor. > 2. The capacitor must be a non electrolytic and between 0.01 and 0.47 > uF. The reason I say this is an electrolytic can be connected back to > front, or or might be leaky. If you use a mylar or similar, it can't be > connected wrongly. > 3. You must use a digital voltmeter. Grand-dad's old analogue VOM > probably has a low input impedance. What meter are you using? Make > sure the meter is set to DC volts. > 4. Refresh the pin as fast as you can > 5. If this doesn't work, try one of the other output pins. You may have > > damaged a pin. > 5. Tell us what you get when you've done ALL of this. > neil > > > Sebastian P. E. wrote: > > > Do not misunderstand me. My readings are NOT good, just that the > > hardware problem isn't much of a problem any more! That single > problem > > is gone. The strange voltages from the chip are still the same! > > > > Best regards > > Sebastian Probst Eide > > Web: <http://dagensstart.com/> Dagensstart.com > > Email: <mailto:> > > Phone: +47 9797 0000 > > > > -----Original Message----- > > From: Sebastian P. E. [mailto:] > > Sent: 22. oktober 2003 07:20 > > To: > > Subject: RE: [BasicX] PutDAC - strange voltages :( > > > > Hi Tom. > > After I connected ground on the two boards the problem disappeared. > > My readings are now good: > > > > GRN - GRN : 0V > > 5V strip on dev board and: > > -GND on dev board: 4.98V > > -GND on s.board: 4.98V (obviously) > > Positive strip on the s.board and > > -GND on dev board: 6.06V > > -GND on s.board: 6.06V (obviously) > > -5V strip on dev board: 1.08V > > Directly connected to PIN13 and GRN: 0.00-0.10V > > Directly connected to PIN13 and GRN through a low pass filter: > 0.20-1.0V > > (depending on the different nondimVolt values (The PutDAC is called > once > > every 5 milliseconds)) > > > > > > > > Best regards > > Sebastian Probst Eide > > > > > > -----Original Message----- > > From: Tom Becker [mailto:] > > Sent: 21. oktober 2003 04:51 > > To: > > Subject: RE: [BasicX] PutDAC - strange voltages :( > > > > Before you worry about code and low-pass filters, you need to solve > the > > hardware problems that you listed in a previous message: > > > > > Positive pole on the s.board and gnd on the dev board while the chip > > is in the dev board, I get: 0V (Should have been 6.06V as with the gnd > > on the s.board!) > > > +5 on the dev board and the gnd on the solderless board I get: 0.28V > > (should have been 4.98V!) > > > gnd on the dev board and the gnd on the s.board I get: -0.38V! > (should > > have been 0.0V!!) > > > > Until these are what they should and must be, you should defer more > > complex notions. > > > > > > Tom Becker > > --... ...-- > > www.RighTime.com > > The RighTime Clock Company, Inc., Cape Coral, Florida USA > > +1239 540 5700 > > > > > > > > > > > > > > > > > <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 > > > 554205:HM/A32163/R=0/SIGn0nglqg/*http:/www.ediets.com/start.cfm?co > > de0510&media=zone> click here > > > > > > > <http://us.adserver.yahoo.com/l?M4081.4074964.5287182.1261774/D=egrou > > pmail/S=:HM/A32163/rand75382935> > > > > ">http://docs.yahoo.com/info/terms/> Yahoo! Terms of Service. > > > > > > > > > > > > > > > > > > > > > > > <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 > > > 554205:HM/A06996/R=0/SIGp5b9ris/*http:/www.ediets.com/start.cfm?co > > de0509&media=atkins> click here > > > > > > > <http://us.adserver.yahoo.com/l?M4081.4074964.5287182.1261774/D=egrou > > pmail/S=:HM/A06996/randb8306793> > > > > ">http://docs.yahoo.com/info/terms/> Service. > > > > > > > > > > > > > > > <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 > 554205:HM/A06996/R=0/SIGp5b9ris/*http://www.ediets.com/start.cfm?c > ode0509 > <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 > 554205:HM/A06996/R=0/SIGp5b9ris/*http:/www.ediets.com/start.cfm?co > de0509&media=atkins> &media=atkins> > > > > > > > > ">http://docs.yahoo.com/info/terms/>. > <http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06 > 554205:HM/A32163/R=0/SIGn0nglqg/*http:/www.ediets.com/start.cfm?co > de0510&media=zone> click here > <http://us.adserver.yahoo.com/l?M4081.4074964.5287182.1261774/D=egrou > pmail/S=:HM/A32163/rand67302747> > > ">http://docs.yahoo.com/info/terms/> Service. > > <http://www.ediets.com/start.cfm?code0509&media=atkins" target="_blank" rel="nofollow">http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06554205:HM/A32161/R=0/SIGp5b9ris/*http://www.ediets.com/start.cfm?code0509&media=atkins > > ">http://docs.yahoo.com/info/terms/>. |
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Reply by ●October 21, 20032003-10-21
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Well, the pin was set to tri-state mode... but I changed to an output mode but still got the same results till I realised the chip documentation said the following: utDAC turns the selected pin into an output pin independent of any other setting.br /> So it shouldn really matter what state it is in at default does it? Most probably I am wrong, but at least that was what I understood from the documentationcorrect me if I am wrong! Best regards Sebastian Probst Eide -----Original Message----- From: Tom Becker [mailto:] Sent: 20. oktober 2003 19:47 To: Subject: RE: [BasicX] PutDAC - strange voltages :( > ... I still didn get voltages above 1V... Is the pin in tri-state? Tom Becker --... ...-- www.RighTime.com The RighTime Clock Company, Inc., Cape Coral, Florida USA +1239 540 5700 Yahoo! Groups Sponsor <http://rd.yahoo.com/M%9395.3614674.4902533.1261774/D=egroupweb/S06 554205:HM/A24963/R=0/SIGo885gmo/*http:/hits.411web.com/cgi-bin/aut oredir?campU6&lineid614674egroupweb&pos=HM <http://us.adserver.yahoo.com/l?M%9395.3614674.4902533.1261774/D=egrou pmail/S=:HM/A24963/randr0554955> ">http://docs.yahoo.com/info/terms/> Service. |
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Reply by ●October 21, 20032003-10-21
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> nondimvolt: measured value: > 0.25 1.3 volts > 0.5 2.4v > 0.75 3.5v > 1.0 4.6v This non-linearity is interesting if not disturbing. Assuming that your Fluke has a typical input impedance of about 10Megohms (like an inexpensive RadioShack/Tandy multimeter that I just tried [1.585volt directly across a battery, 0.786volt when measured through 10Megohms]), the TC of that RC (cap=.1uF) is (10e6*0.1e-6)= 1.0sec, i.e the voltage droops about 30% in one second after the charge current is disconnected (Hi-Z'd from the BX-24). The charging TC is (10e3*0.1e-6)= ~0.001sec. That's a charge to discharge ratio of 1000:1 which should, I'd think, be sufficient to yield pretty accurate meter results. Why is there 8% error when nondimvolt 0.25 doubles to 0.5 ((2*1.3-2.4)/(2*1.3)), and 4% error when 0.5 doubles to 1.0 (2*2.4-4.6)/(2*2.4))? Seems very high to me. Tom Becker --... ...-- www.RighTime.com The RighTime Clock Company, Inc., Cape Coral, Florida USA +1239 540 5700 |
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Reply by ●October 21, 20032003-10-21
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Hi Tom Its a fluke 8050A which according to the handbook is 10megs/100pF on all ranges, and when checked with a 1% 3.3m resistor, calculates at 11.1meg ( 1.338 volts and 1.032 volts with and without the series R). I just did the numbers again with closer intervals as follows: Readings were allowed to stabilize for 1 min at each interval, and were repeated 10 min later. Only the LSD varied in the second reading. Non Dim Volts output(0.1 mylar) 0.47 Mylar: (R = 10k in both cases) 0.0 0.207 0.209 0.01 0.258 0.260 0.1 0.659 0.656 0.2 1.088 1.088 0.3 1.536 1.536 0.4 1.966 1.966 0.5 2.406 2.403 0.6 2.849 2.846 0.7 3.296 3.293 0.8 3.739 3.719 0.9 4.174 4.170 1.0 4.608 4.603 Tom Becker wrote: > > nondimvolt: measured value: > > 0.25 1.3 volts > > 0.5 2.4v > > 0.75 3.5v > > 1.0 4.6v > > This non-linearity is interesting if not disturbing. > > Assuming that your Fluke has a typical input impedance of about 10Megohms > (like an inexpensive RadioShack/Tandy multimeter that I just tried > [1.585volt directly across a battery, 0.786volt when measured through > 10Megohms]), the TC of that RC (cap=.1uF) is (10e6*0.1e-6)= 1.0sec, > i.e the > voltage droops about 30% in one second after the charge current is > disconnected (Hi-Z'd from the BX-24). The charging TC is (10e3*0.1e-6)= > ~0.001sec. That's a charge to discharge ratio of 1000:1 which should, I'd > think, be sufficient to yield pretty accurate meter results. > > Why is there 8% error when nondimvolt 0.25 doubles to 0.5 > ((2*1.3-2.4)/(2*1.3)), and 4% error when 0.5 doubles to 1.0 > (2*2.4-4.6)/(2*2.4))? Seems very high to me. > Tom Becker > --... ...-- > www.RighTime.com > The RighTime Clock Company, Inc., Cape Coral, Florida USA > +1239 540 5700 > > <http://www.ediets.com/start.cfm?code0509&media=atkins" target="_blank" rel="nofollow">http://rd.yahoo.com/M4081.4074964.5287182.1261774/D=egroupweb/S06554205:HM/A06996/R=0/SIGp5b9ris/*http://www.ediets.com/start.cfm?code0509&media=atkins > > ">http://docs.yahoo.com/info/terms/>. |
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Reply by ●October 21, 20032003-10-21
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Sorry. Brainfade. Should be: ... i.e. the voltage droops about 70% in one second... and later, ... The charging TC is (10e3*0.1e-6)= ~0.001sec, i.e. the voltage rises to 70% of the final voltage in one millisecond... Tom Becker --... ...-- www.RighTime.com The RighTime Clock Company, Inc., Cape Coral, Florida USA +1239 540 5700 |
Reply by ●October 21, 20032003-10-21
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It's the offset at nondimvolts=0; silly me, expecting 0 to yield 0.
Taking that offset into account, the results are much better. Non Dim Volts output(0.1 mylar) 0.0 0.207 -0.207= 0.000/4.401= 0.0 0.01 0.258 -0.207= 0.051/4.401= 0.0115 0.1 0.659 -0.207= 0.452/4.401= 0.103 0.2 1.088 -0.207= 0.881/4.401= 0.200 0.3 1.536 -0.207= 1.329/4.401= 0.302 0.4 1.966 -0.207= 1.759/4.401= 0.400 0.5 2.406 -0.207= 2.199/4.401= 0.500 0.6 2.849 -0.207= 2.642/4.401= 0.600 0.7 3.296 -0.207= 3.089/4.401= 0.702 0.8 3.739 -0.207= 3.532/4.401= 0.803 0.9 4.174 -0.207= 3.967/4.401= 0.901 1.0 4.608 -0.207= 4.401/4.401= 1.000 Superb. Thanks for the effort, Neil. Tom Becker --... ...-- www.RighTime.com The RighTime Clock Company, Inc., Cape Coral, Florida USA +1239 540 5700 |
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