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Aaron KC2NDA Arduino Enhanced Display & Control Thread



  • edited May 2017

    Here is the Volume Potentiometer that is being replaced by the Digital Potentiometer.


    Looking at this circuit, you can see the path that the potentiometer takes before it goes to the chip next to it. There are VIAs (Or hole throughs) that go to the other side of the board. This picture will show where they are and how I scratched the lacquer off of the board:

  • edited April 2017

    Wires are now soldered and connected to the breakout board.

    Here is the final wiring for the first digital potentiometer and the RSSI:

    Yellow wires are for 10K potentiometer from Ritron to the AD5220 Digital Potentiometer. The AD5220 uses a clock signal, up/down, and chip enable pins. The green wire is the RSSI and is going directly into one of the analog pins on the Arduino currently through a 10K Ohm resistor. That might change but will test it first. The clock signal is being shared for the digital pot and the reading of the EEPROM from the ritron. So it is important to note that this is why there are "chip enable" pins on most SPI devices or "Slave Select".. You could have more then one "Slave" hooked up to a "Master" at one time. So how do you tell which device you want to talk to? This is how.. ;)

    You can see the AD5220 (Digital Potentiometer) on it's own breakout board from the SOIC package to the DIP. This is located just under the 2 ceramic bypass capacitors.

    Radio booted up without any problems. So that is a good sign!

  • edited April 2017

    Here is the pinout for the AD5220 Digital Potentiometer:

    You send a clock signal along with whether you want to go up or down using the U/D pin and you have to make sure you toggle the CS (Chip Select) pin.

    The B1 or A1 pin are both really the same except one will be going down in value while the other is going up. So you might have to flip the up/down depending on which one you hook to. I just so happened to hook mine up to B1, so we will see how that works out. The other side is the W1 or "Wiper" pin. This is the leg and A1 or B1 that has the resistance you want to hook to the Ritron.

    Once I am done, I will post the code to access and change the AD5220.

  • so yeah... "LIKE!"
    nice work!

  • edited April 2017

    Here are some closeups of the AD5220 digital potentiometers populated on the SOIC to DIP package boards:

    These little boards make soldering to breadboards a whole lot easier.

  • edited April 2017

    Here is the RSSI S meter for the OLED. Seems to work great.. But still needs to be tested for accuracy. The was using a dummy load and it shows the noise floor close to what my Icom 746 Pro is set at. So this part looks to be working. There seems to be a bug in the Ritron though, first test showed RSSI voltage settings to be 2.2V being the highest. At some point it lowers itself to .80V. Not sure why yet, but will have to investigate further. Maybe K2GOG has some similar findings.

  • Nice work on the integration of the RSSI into the Arduino with visual readout. We need to use a voltage divider to drop down the raw voltage output of the RSSI pin to normalize what would be output at full scale.

    Have a look again at this thread for some of the raw reading I have taken.

    I have since confirmed this on two different MPET boards where the raw readings are "within close enough" range.

    The V divider would need a variable resistor to accommodate any adjustment.

    Suggest we normalize on max RSSI reading to work out to S9+60 which would be 5mV (74dBuV) which is standard for VHF and above up to 3GHz. HF uses a different set of figures.

    I need to spend some time to make the divider. Will report back in unless you make progress before me.

  • oh, question: what supply voltage are you running the MPET at Aaron? That has an effect on the RSSI output I noticed.

  • 12V. I am not sure why we would need the voltage divider. I don't think the RSSI would go over 5V because it is directly being fed into the Microcontroller. I would imagine they are dealing with this already. Since it is 5V regulated, I wouldn't think that the input voltage would affect the RSSI. But of course we should test some more. At least the RSSI engine is done! It will be easy to tweak.

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