I'm hoping someone can help me with my problem
The on-board +5vdc voltage regulator will rarely be exactly 5.000 volts as it too has a standard tolerance.
Hi retrolefty,Actually I noticed this as well.QuoteThe on-board +5vdc voltage regulator will rarely be exactly 5.000 volts as it too has a standard tolerance.I do have some questions over this, during idle time, the voltage is around 5.01 V but when I start to drive the h-bridge circuit, the voltage goes to 5.3 V. Is the arduino driving in more voltage from my usb connection?Another weird thing with multimeter vs arduino readings is during idle time the difference in the readings is around 20 mV but when I drive the h-bridge, the reading is quite a bit different of about 300-500 mV instead of the usual 0.26 V (multimeter) it turns into 0.50+ V (multimeter) which I'm thinking is maybe tied with the voltage in the supply. While this seems a bit logical, the arduino goes from 0.22 V to 0.15 V which I think is really weird. I'm sorry I'm a bit of a noob with arduino and I can't really tell why this happens.
A first guess is that you haven't taken any steps to prevent interference from your high power PWM circuitry being picked upby the temperature sensing analog circuitry. Switching large currents is usually the recipe for interference. Is the H-bridge decoupled?Is the high current circuitry kept away from the temperature sensor?
Just a thought occured to me... the sampling of the arduino ADC usually takes how long? I actually find it interesting that whenever I sample the 6 channels altogether, there will be some discrepancy on one to three pins... maybe when I turn-on the pwm it consumes a bit more processing power and thus would need to take longer / more cycles to get the analog voltage?
I'm thinking to use op-amps to amplify the LM35 output to a more decent range of voltages instead of using the mV range. Do you think this can help?