Arduino used to provide analog inputs to FrSky SPort
This is made available to replace the X8R2Analog device that is no longer available.
The Arduino Pro Mini used MUST be a 8MHz, 3.3V version.
The analog inputs accept voltages from 0 to 3.3V only. To measure higher voltages, you must add a resistor divider on each analog input used.
The default operation is to use the first analog input, and this is sent as the A2 value. The second analog input may also be used. This is auto-detected as in use when it has a voltage less then 3.2V applied. An internal pull up resistor holds the voltage at 3.3V if left unconnected. By default, this second analog value is returned as Temperature 2, but if the input labelled "ID Select" is connected to ground, the values is returned as A1.
Analog inputs labelled A3 and A4 may also be used, they will only be sent over the SPort if the corresponding "Enable" signal is connected to ground.
The "Scaling" option link operates on the A2 value. If left unconnected, A2 operates normally. If the option is connected to ground, the analog value is scaled. The X8R2Analog device used a resistor divider of 15K and 3.3K. This is suitable for up to 4S Lipo. If you want to measure only a 3S Lipo, and use this same resistor divider, then grounding the link option causes the measured value to be scaled as though the divider was 10K and 3.3K.
The physical ID default value is 0x1B, as on the X8R2Analog, but with this version you may change it using the ChangeId app accessed from the ersky9x bootloader or the ChangeID option in "Maintenance Mode" of ersky9x.
Connections:
Voltage divider:
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