Add digital Flow sensor to existing code for Mini Arduino Pro (ATmega328P):
1) The flow sensor provides a pulse signal from a hall-effect sensor.
2) The sensor will read the water flow through the heater and the results will be an additional condition for turning the heater element on or off, similar to the pressure sensor.
3) The MCU will count the pulses per second (Hz) (or perhaps we break it into 250mS bits?) for the flow to determine if the flow is within operating conditions for the heater.
a. A flow sensor count below or above the range will cause heater element to turn off.
b. A count below the low threshold means there is not enough water flowing through the heater to be safe.
c. A count above the high threshold means there is likely air in the line causing the sensor to spin faster. Air in the line is not safe for the heater.
d. A count between the thresholds means the heater is safe to operate.
e. If the flow returns within the range, the heater can turn back on.
4) The low and high threshold counts should be adjustable and need to be accessible in the “user configurable section” of the “Heater_Control” source code.
5) Still need to determine the following:
a. Determine sensor PPS (Hz) within our flow range and at specific flows to determine our count range.
Minimum flow is 236ml/min (less than = turn off heater, not enough flow)
Optimal flow is 295ml/min (equal = heater ok)
Maximum flow 354ml/min (greater than = heater off, likely air is present)
6) Keep the pressure input code “as-is”.