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15212Re: [tracker2] Re: OT USB Telemetry

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  • Scott Miller
    Feb 7, 2013
    • 0 Attachment
      Sounds like maybe there's something wrong with the voltage dividers.
      There's a green resistor pack on the left side of the board, and a row
      of resistors close to the CN4 pins. Do those look OK?

      As for the resolution, the ADC can do 12 bits, and the telemetry fields
      could represent 000-999, though that's not in the original spec. I
      might make that an option, to scale the 12-bit samples to fit that range.

      Scott

      On 2/7/2013 6:43 AM, n9tkf wrote:
      > I did some testing last night and found if I put 5 volts on any of the
      > analog pins on CN4 that all of them would give me a max count of 164.By
      > max count I mean the maximum number reported in the telemetry output
      > (TLM: 164). This would make sense since Vdd is ~4.2 volts as measured on
      > CN4-1. My battery voltage reported in the comment section is 16.4V and I
      > am running off a 12V battery. Not sure why the numbers don't match. By
      > having only 164 counts the resolution of my LM355 is 4.64 degF. Would it
      > be possible to program more resolution into the telemetry inputs?
      >
      > --- In tracker2@yahoogroups.com <mailto:tracker2%40yahoogroups.com>,
      > Scott Miller wrote:
      > >
      > > Yes, it should read 200. It might not get all the way to 200, depending
      > > on the exact supply voltage the MCU is getting. The limit is actually
      > > 4xVdd and on newer units with the isolation diode Vdd is slightly less
      > > than 5v. You should still have to put in 16.4v to get a reading of 164,
      > > though.
      > >
      > > Scott
      > >
      > > On 2/4/2013 3:48 PM, n9tkf wrote:
      > > > Thanks Scott for looking into this. I do have a question though, if I
      > > > put 20 volts on say CN-4 pin 3 (analog input 1), what value would be
      > > > output in the telemetry string for analog 1? Would it be 200? It seems
      > > > my OT USB is maxed out at 164 with only 5 volts.
      > > >
      > > > --- In tracker2@yahoogroups.com <mailto:tracker2%40yahoogroups.com> ,
      > > > Scott Miller wrote:
      > > > >
      > > > > There's not presently an adjustment, but I should be able to add
      > that in
      > > > > the next firmware version. Everything is referenced to an
      > internal band
      > > > > gap reference, so it should be independent of the supply voltage
      > (which
      > > > > runs lower than 5v because it's got a series diode) and I can simply
      > > > > adjust what the expected voltage of the band gap is.
      > > > >
      > > > > Scott
      > > > >
      > > > > On 2/4/2013 5:13 AM, Joe Della Barba wrote:
      > > > > > My OT-3M has been reporting 0.3 volts low for about a year now.
      > > > > >
      > > > > > I could change the telemetry by sending a message if I can
      > remember the
      > > > > > format, but that won't help the comment field.
      > > > > >
      > > > > > So – is there an adjustment for this?
      > > > > >
      > > > > > Joe Della Barba
      > > > > >
      > > > > > joe@
      > > > > >
      > > > > > N3HGB-5
      > > > > >
      > > > > > *From:*tracker2@yahoogroups.com
      > <mailto:%2Atracker2%40yahoogroups.com>
      > > > [mailto:tracker2@yahoogroups.com <mailto:tracker2%40yahoogroups.com>
      > > > ] *On
      > > > > > Behalf Of *n9tkf
      > > > > > *Sent:* Sunday, February 03, 2013 5:44 PM
      > > > > > *To:* tracker2@yahoogroups.com <mailto:tracker2%40yahoogroups.com>
      > > > > > *Subject:* [tracker2] OT USB Telemetry
      > > > > >
      > > > > > I have an OT USB that I am using for telemetry. It seems that the
      > > > > > telemetry inputs on CN-4 are a bit skewed. CN-4 pin 5 is connected
      > > > > > directly to my battery. Measured voltage is 13.1 but the telemetry
      > > > value
      > > > > > reported is 164. I expected the telemetry value to be 131. I also
      > > > > > noticed my reported battery voltage in the comment field is 16.4V.
      > > > > >
      > > > > > Firmware version 55871 installed.
      > > > > >
      > > > > > CN4 pin 1 should be directly connected to the +5 volt supply
      > according
      > > > > > to the schematic. The voltage on this pin measures 4.23V. I
      > > > measured the
      > > > > > output on the +5V regulator and it is 4.99V. The 1 wire
      > temperature pin
      > > > > > 2 seems to be ok. I have a light sensor and moisture sensors
      > connected
      > > > > > to the CN4 header also.
      > > > > >
      > > > > > I have EXTTEMP on, and voltage and temperature reporting in the
      > comment
      > > > > > section. Here is a link to my telemetry page :
      > > > > > http://aprs.fi/telemetry/a/N9TKF-4
      > > > > >
      > > > > > Has anyone encountered this problem and have a solution?
      > > > > >
      > > > > > John N9TKF
      > > > > >
      > > > > >
      > > > >
      > > >
      > > >
      > >
      >
      >
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