PIDKiln - PID Temperature Controller to Ceramic/Glass/Metal Kiln

DESCRIPTION

This is "yet another" PID temperature controller. I've made this one, because bought one was crappy and I needed something solid. There are two or three other DIY controllers "on the market" but this one, at least I see it this way :), is much more robust and has all features I needed.

Key features:

interface accessible both from LCD screen and WWW webpage
unlimited (only by storage) kiln programs number,
program file size limited to 10KiB (but this is artificial limit - can be extended)
internal ESP storage for programs, data, logs (perhaps later SD - but I'm not sure yet)
local preferences on disk, editable with Web interface
online monitoring, program management, editing, graphs and kiln controll
build in clock synchronised with NTP servers (if Internet connected)
safety features build in (temperature run out protection, probe failure, SSR failure, kiln insulation failure)
simply cool and cheap (comparing to commercially available products) all in one solution

Supplies:

ESP32-Wrover board
MAX31855 breakout board (or two)
K-type thermocouple
DC->AC solid state relay

Kind of optional, but recommended:

128x65 dot matrix LCD 12864B v2
Rotary encoder with button

Optional:

DC/AC secondary relay - like SLA-05VDC-SL-C (240V/30A) mechanical relay
Additional MAX31855 board with K-type thermocouple for housing temperature measuring
Perhaps a kiln :)

Step 1: Wiring

Description:

LCD

Connected to one of three SPI on ESP32 - called VSPI (MOSI-23, MISO-19, CLK-18, CS-5)

ESP32   | LCD
--------|---------
+3.3V   | BLA (this can be also +5V if you wish)
GND     | BLK
4       | RST
GND     | PSB
+5V     | VCC (This should be - for ESP sake - 3,3V, but my LCD doesn't work with lower voltage. Try first with 3,3V)
GND     | GND
5       | RS
18      | E
23      | R/W

Encoder

ESP32   | Encoder
--------|---------
+3.3V   | 5V/VCC
GND     | GND
32      | Key
34      | S2
35      | S1

MAX31855

Connected to one of three SPI on ESP32 - called HSPI (MOSI-13, MISO-12, CLK-14) CS-15/27

EPS32   | MAX31855 A
--------|---------
+3.3V   | VCC
GND     | GND
12      | SO/DO (slave output/data output)
14      | SCK (clock)
15      | CS (chip select)

EPS32   | MAX31855 B
--------|---------
+3.3V   | VCC
GND     | GND
12      | SO/DO (slave output/data output)
14      | SCK (clock)
27      | CS (chip select)

Relays

ESP32   | SSR
--------|-------
GND     | GND
19      | IN

ESP32   | EMR (SLA-05VDC-SL-C)
--------|----------------
GND     | GND
21      | IN
5-48V*  | VCC

* Do not connect 5V from ESP - use external source. This can be any 5V-48V power supply with around 1W power.

Required source code is part of the Github: https://github.com/Saur0o0n/pidkiln

Some more information you can find on my webpage: https://adrian.siemieniak.net/portal/tag/PIDKiln/

3d printable case: https://www.thingiverse.com/thing:3907643

Step 2: Assembled Controller