Would like to customize a different ohmic heater

[Dudic0]

Hi,
I Love the work done so far, thanks!
I would like to customize the system to a specific heater, is there any easy way to change heater values like resistance and TCR values? I have a heater with 12ohm in 0c and a TCR of 3850ppm/k.

Thanks and sorry if this is the wrong place for this type of request.

David

[Ralim]

Hello,

Changing tip resistance is easy, changing thermal response isn't as simple as you need to recreate the lookup table

IronOS/source/Core/BSP/Pine64/ThermoModel.cpp

Line 12 in f13b7be

const uint16_t uVtoDegC[] = {

To use the new uV<-> temperature curve

[Dudic0]

Thanks! so i need to recreate this table using a voltmeter and a reliable heating source..

Could you please point me to where do i enter the heater resistance value in the code? Does the parameter represent a certain temperature reference like 25c or 0c and is there also a way to change the thermocouple type and enter its coefficient? I would like to experiment with different TC than in the stock.

Thanks again!
David.

[Ralim]

Hia,
So it depends on what device you are modifying as to what you will need to change.
You need to change TIP_RESISTANCE. You can find this in source/Core/BSP/<brand>/configuration.h. Generally near the bottom.
This is the ohmic resistance of the tip around normal operating temp (its approx, doesnt need to be exact. Not critical).
its stored in 100milliohm increments, so 12 ohms would be 120.

For the Thermocouple, there isnt really a "type" but instead a lookup table for uV -> Temp.
If you look in source/Core/BCP/<brand>/ThermoModel.cpp there is the table for these lookups that you would need to modify (the one suiting your device). To estimate a linear function for testing you could probably get away with just putting in end values and it will linearly interpolate those for you.

[Dudic0]

Thank you. I found all references.
Could you share, what would like be the approach to modify "TIP_THERMAL_MASS 65 // TODO, needs refinement"
As my element has a smaller heating mass..

Thanks again, you are vey helpfull.

[Ralim]

Try without setting it first, then if your are overshooting on temp reduce it. If you are underdamped (not hitting 100% power steering great up) increase it.

You can be quite wrong and it will still work just be a little unstable