zunz / popc

Firmware for Arduino and ESP8266 based coffee roaster control

RoboPopc is an application for coffe roast control and logging. The software supports Arduino and ESP8266 development boards with software PID controller and drivers for LCD display.

Without additional hardware either platform can connect to 'Artisan' roaster logging application, providing 'virtual thermocouple' readings of Bean Temperature to Artisan.

With additional hardware 2x16 I2C display board, MAX31855 thermocouple interface and PWM drive for solid state relay are supported. On the ESP8266 version wifi connection and MQTT messaging allows for control via web based applications, a serial interface is necessary only for code loading.

Control of the roasting process is by any of: Artisan Logger over serial interface, manual setting of temperature / time ramps and target setpoints over a serial interface or manually adjusting temperature ramp or PWM percentage by way of a 16 position rotary encoder switch.

PWM control may be selected to be either by slow On-Off cycling, 3mSec granularity in 3 Sec cycles or, by using the processor's PWM at an approx 31Hz rate.

Installation is done using the Arduino IDE, for ESP8266 the supplementary steps for ESP8266 development must be done. This code is supplied as an Arduino sketchbook, for ESP8266 the 'Ticker Scheduler' code and headers must be copied into this sketch's folder. There are compiler switches near the beginning of the code for processor type and for various hardware options to be included.

Sections (units) in this code, ordered alphabetically: bbrd 'billboard' posts info to either / both of 2x16 LCD display / Serial Port frnt deprecated, sends data over Serial to Frontside / Process apps on PC for PID tuning
lcds support for I2C 2x16 LCD display
mqtt ref ingo MQTT message queuing publish / subscribe protocol for control via PC MQTT client
offn Slow Off/On approx 3sec cycle PWN for SSR controlled heater
pidc PID controller for PWM powered temperature control; a delta-time incremental PID pwmd 8-bit PWM control via hardware pwm pins prof Profile control; selects auto/manual temp setpt, manual pwm width, real/fake temp sensor rots Rotary 16way encoded ( 4pin + common) selector switch manager tcpl MAX31855 SPI thermocouple temperature sensor or virtual temp readings for debug user receive user's or Artisan commands via serial port, MQTT for setpoint, ramp, profiles

Arduino H/W details:

pins: lcdi: A4 A5; tcplSPI: D3 D5 D10 pwm: D9

Legend / Mode Indicators; Upcase: User Set; LowCase: Auto/Sensed value; User entry: either case; a toggle run time interface to Artisan c centigrade entry/display d toggle diagnostic verbose messages on serial f fahrenhet entry / display, internals always are Centigrade i info strings and 'billboard' to serial l logging (artisan csv) to serial p profile (tbd) r ramp C/F Degrees per minute, enter before target setpoint s setPoint C/F temp w pwm width override, disssabled PID y tbd pwm freq Hz z reset total timecount