Reflow-Controller

This page is a work in progress!

The Reflow-Controller was built to control different kinds of reflow ovens, hotplates and whatever is coming to my mind in the future. It is based on the ESP32-S2 (datasheet) and thus can be programmed to be used with a WiFi App or whatever. Nevertheless, it has an onboard OLED display and three buttons included to be used as a standalone solution either.

The Youtube video shows the assembly of a complete reflow oven system and the first tests.

Features of the PCB:

ESP32-S2 MCU
2x MAX6675 thermocouple sensor input
2x Fan output (inductive loads/flyback diodes included)
2x Solid state relay output
3x User button
1x APA102 user LED
1x Buzzer
1x Servo motor output
0,96" OLED display
Optional ACDC converter (HLK-PM05, HLK-PM12) which can be separated if not used
Optional I2C (QWIIC) connector

GPIOs

The ESP32-S2 is connected like this:

Function	GPIO	Mode
SSR1	GPIO1	Output
SSR2	GPIO2	Output
Servo	GPIO3	Output
Fan1	GPIO5	Output
Fan2	GPIO6	Output
CLK	GPIO7	SPI
MISO	GPIO9	SPI
MOSI	GPIO11	SPI
CS1	GPIO12	SPI
CS2	GPIO13	SPI
Buzzer	GPIO15	Output
USB D-	GPIO19	CDC
USB D+	GPIO20	CDC
SDA	GPIO33	I2C
SCL	GPIO35	I2C
Button1	GPIO36	Input
Button2	GPIO39	Input
Button3	GPIO40	Input
LED CLK	GPIO37	LED
LED DATA	GPIO38	LED
OLED RST	GPIO45	Output

ACDC power supply

The upper part of the PCB can be used as a power supply for the whole board as well as the higher voltage outputs (SSRs, Fans). If not used, it can be separated from the main board and may be used in another project where an ACDC adapter is needed.

The main board is equipped with an LM1117 3.3v voltage regulator which can be feed with 15v max. The output voltage of the ACDC power supply is the voltage for the SSR and the fan output channels. If you wanna use a servo motor in your project, make sure that the power supply has the correct voltage for the motor (probably 5v).

The HLK-PMXX module for the upper part of the PCB can be placed in two ways - on the bottom or on the top side. This gives the possibility to mount the whole PCB behind an acrylic glass (or whatever) so that the buttons as well as the OLED display are accessible. The two jumpers can then be used to select which signal is VCC and which one is GND. Keep in mind that there are high voltage pins on the top side of the PCB when mounting the power supply on the bottom side! I've designed a 3D-printable cover, so that these pins cannot be touched accidentally. (Should be mounted in both cases)

The board can also be powered via USB-C, but keep in mind that the output channels and the servo motor are not powered in this case (initially it is just available for flashing the board).

Case & Spacer

As I wanna hide the whole PCB behind an acrylic glass (transparent) I've designed a simple case for the high voltage pins at the top and a spacer at the bottom of the PCB. In the end, the acrylic glass will be laser-cutted with some bridges for the buttons. Distance between PCB and acrylic glass is 5mm.

mfkiwl / reflow-controller Goto Github PK