7000DLE MkII PSU Voltage calibration

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neoklis
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7000DLE MkII PSU Voltage calibration

Postby neoklis » Fri Jan 17, 2020 5:44 pm

Hi,

I am writing some code to convert the PSU Voltage ADC readout (Protocol II, Hardware to PC, High Priority Status Packet, bytes 49-50) to actual PSU volts. I used the formula for the 200D in the Protocol II v3.8 PDF manual: Calibration constant for Supply V: V = ADC value /4095 * constant, constant = 5.0. (Could not find a formula for the 7000DLE MkII).

The results I get is about 2.05, which is wrong I am sure. More likely the formula for the 200D is way out for the 7000DLE. Can anyone please supply the right calibration constants for the PSU volts? I could use a DVM to measure it and adjust the numbers in the code but this is not likely to be right.

My thanks in advance.
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w-u-2-o
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Re: 7000DLE MkII PSU Voltage calibration

Postby w-u-2-o » Fri Jan 17, 2020 7:40 pm

Are you writing software or firmware?
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neoklis
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Re: 7000DLE MkII PSU Voltage calibration

Postby neoklis » Sat Jan 18, 2020 4:29 am

w-u-2-o wrote:Are you writing software or firmware?

I am writing software, my own P2-based client for the 7000DLE. Its already functional in receive and I am trying to add a widget to display PSU volts. The decode of bytes 49 and 50 evaluates to about 1660 so 1660 / 4095 * 5 = 2.02
Bryan W4WMT
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Re: 7000DLE MkII PSU Voltage calibration

Postby Bryan W4WMT » Sat Jan 18, 2020 10:12 am

Hi Neoklis,

You may have better luck with that question over in the OpenHPSDR reflector.
Have you joined that yet?

73
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neoklis
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Re: 7000DLE MkII PSU Voltage calibration

Postby neoklis » Sat Jan 18, 2020 10:31 am

Bryan W4WMT wrote:Hi Neoklis,

You may have better luck with that question over in the OpenHPSDR reflector.
Have you joined that yet?

Hi Bryan,

No, I will look it up and join.

Having looked into the Thetis source code, it seems that there is one more factor to take into account, the voltage divider ratio used to reduce the supply voltage to a suitable value for the ADC. For the Hermes board in Thetis its 5.7:1. I don't know what it really is in the Orion II but I estimate around 6.9:1, by measuring the PSU with a DVM (~13.9v) and dividing with ~2.02, the result from the High Priority packet.

73's
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w-u-2-o
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Re: 7000DLE MkII PSU Voltage calibration

Postby w-u-2-o » Sat Jan 18, 2020 12:24 pm

neoklis wrote:
w-u-2-o wrote:Are you writing software or firmware?

I am writing software, my own P2-based client for the 7000DLE. Its already functional in receive and I am trying to add a widget to display PSU volts. The decode of bytes 49 and 50 evaluates to about 1660 so 1660 / 4095 * 5 = 2.02

Since this topic doesn't therefore belong in a firmware sub-forum I am moving it to the All Other Clients sub-forum.

And, as you've already found out, the answer is to be found in the Thetis source code.

73,

Scott

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