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The main window of PinByPin (the program for the main port is shown in this case) can be seen below:

For the Main port, pins 1 to 4 are the active ones. The temperature readings for each sensor are displayed first (the delta between them can be clearly seen at the bottom of the window). Then, for each pin, we can see:

An explanation on partial power output is due: if a pin is simply ON, it will deliver all possible power to the device connected to it. This is ok for instance for fans, as they draw very little power. However, heater bands can draw several amperes if supplied with 12V (typicall Armadillo power supply), and this can be harmful:

  1. the heater band will heat too much (they are seldom used at 100%, but rather at minimum power just to avoid condensation), inducing hot air currents
  2. the internal Armadillo electronics can burn if the band is long enough (a band with internal resistance of 12 ohm will draw 1A at 12V)

... thus we adopted the PWM, or better said, sPWM (for slow PWM), as the switching is quite slow. So a 10% output means there will be full supply 10% of the time, no supply at all the remaining 90%, and so on. The goal is to adjust the heating of the power bands and keep total power drawn (per port) at 1A maximum .

 


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