Firmware and docs for new reflow oven.
Project codename: Oven One :-)
In recent Ubuntu versions you'll need the following packages:
- python3
- python3-serial
- arduino
We're using a WZP PT100. There is a table for it but you can summarize them with a quadratic equation.
| Temperature | Resistance |
|---|---|
| 0 | 100 |
| 100 | 138.51 |
| 200 | 175.86 |
| 300 | 212.05 |
Temperature = 0.001113 * r * r + 2.329774 * r - 244.0946281
A line wasn't enough to summarize the table.
This StackOverflow answer was useful.
Using the following equation you can get one that gives you a voltage for different thermocouple resistance values.
This is a voltage divider.
Vout = (Vin * R2) / (R1 + R2)
R2 = (Vout * R1) / (Vin - Vout)
We'll use Vin = 5v and we know R1's value, so the only variable is the thermocouple (R2).
For now we're using R1 = 221 ohms (what we measured).
- A0 : ADC input from the Vout formula above (Measuring Vout).
- Pin 3 : Output port 0 (resistance)
- Pin 4 : Output port 1 (resistance)
- Pin 13 (built-in led): Fast blink for error condition (invalid command, for instance).
Messages that are sent to the Arduino. Each command describes what is sent and what is sent back. All communications are in bytes.
- 0 : Select first port. Returns '0' (byte).
- 1 : Select second port. Returns '1' (byte).
-
- : Turns on selected port. Returns '+'.
-
- : Turns off selected port. Returns '-'.
- A : Asks for ADV value of selected port. Returns 'A', and then the ADC value in two bytes (first one is the highest one).
You can select 0 and 1 to do pings to the device. Recommended after startup.
[easy eda project] (https://easyeda.com/cmsvalenzuela/Power_circuit_reflow_oven-b03160d6e52648cb9ea1c21ea43c88d2).
