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| Search found 18 matches |
| Author | Message |
|---|---|
 Topic: How big is internal resistance of AD convertor in 18F4520? |
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| djole_nisam_ja Replies: 2 Views: 3322 |
 Forum: General CCS C Discussion Posted: Tue May 04, 2010 6:46 am Subject: How big is internal resistance of AD convertor in 18F4520? |
| Can anyone tell me how high is internal resistance of AD convertor in 18F4520?
Thanks |
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| Topic: How to use comparator on PIC18F4520 |
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| djole_nisam_ja Replies: 1 Views: 3400 |
Forum: General CCS C Discussion Posted: Wed Apr 21, 2010 2:32 am Subject: How to use comparator on PIC18F4520 |
| Hi,
I would like to, if it is possible, to use comparator on PIC18F4520 to compare Voltage on some input port with Value I defined in source code. Any help would be grateful. Thanks Djole |
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| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Thu Mar 25, 2010 4:25 pm Subject: problem with A/D |
| What is real here ?
First you say 18F4520, then you say 18F4620. Also, your program has a #use delay of 2 MHz with an external crystal (XT fuse). Basically, nobody does this (use 2 MHz crys ... |
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| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Thu Mar 25, 2010 12:56 pm Subject: problem with A/D |
| Always post your PIC. Each PIC has different options for the ADC.
Ok, I forgot. PIC18F4520 |
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| Topic: HowTo define a pin to be digital input pin? |
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| djole_nisam_ja Replies: 7 Views: 44182 |
Forum: General CCS C Discussion Posted: Fri Mar 19, 2010 3:54 am Subject: HowTo define a pin to be digital input pin? |
| I need help with defining pin as digital input pin.
I know how to define it as digital output: set_tris_a(0); // PORTA defined as output */ output_a(0); // PORTA = 0; set t ... |
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| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Fri Dec 25, 2009 4:23 pm Subject: problem with A/D |
| Hi everyone,
just to post my results. I made my circuit with total impedance <2,5KOhm and it work ok. Haven´t yet tried with Vref=4,096V, but even Vref=5V work all right. Thanks for he ... |
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| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 5:15 pm Subject: problem with A/D |
| Oh, Ttelmah, one more thing.
Regarding Vref=4.096V, my board has jumper for changing this (either you would like 5V or 4.096V) but it is just for external ADC(onboard chip MCP3204). So I assume ... |
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| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 4:40 pm Subject: problem with A/D |
| Yeah, I will try oversampling. Speed is what I don't need but accuracy I do need. | |
| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 4:04 pm Subject: problem with A/D |
| I'd suggest that the problem is elsewhere. The accuracy of your Vref, or the source impedance of the circuit itself, or possibly noise on the circuit (because the PIC ADC, is capacitive, it tends to i ... | |
| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 4:00 pm Subject: problem with A/D |
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my impedance is around 15KOhms, so it wouldn´t be that much trouble for the voltmeter, but it could be for the PIC (from what you said about range of 5-10KOhms). I looked for maximum input im ... |
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| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 3:00 pm Subject: problem with A/D |
| See:
In addition, the Thevenin equivalent impedance as seen by the PIC A/D pin should be less than 10k (or is it 5K, you have to check the datasheet) or you may get the accuracy you are looking for ... |
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| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 1:46 pm Subject: problem with A/D |
| Do you say that if I measure voltage on ADC pin (with voltmeter), I am actually not measuring the whole voltage (which measures the PIC) because of the ADC pin´s resistance?Right. You would need an o ... | |
| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 12:24 pm Subject: problem with A/D |
| See:
In addition, the Thevenin equivalent impedance as seen by the PIC A/D pin should be less than 10k (or is it 5K, you have to check the datasheet) or you may get the accuracy you are looking for ... |
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| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 12:15 pm Subject: problem with A/D |
| I'd suggest that the problem is elsewhere. The accuracy of your Vref, or the source impedance of the circuit itself, or possibly noise on the circuit (because the PIC ADC, is capacitive, it tends to i ... | |
| Topic: problem with A/D |
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| djole_nisam_ja Replies: 48 Views: 87702 |
Forum: General CCS C Discussion Posted: Wed Dec 23, 2009 9:26 am Subject: problem with A/D |
| See:
So '3.2' means *at least* 3 digits before the decimal point (adding spaces if reqd) and *at least* 2 digits after the decimal point. Replying here to this old post first, but it is important ... |
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