Project Features

Overview

Espresso Controller stabilizes brew pressure and water temperature using two independent PID loops. The system reads a 0.5–4.5V pressure transducer via ADC averaging and a MAX6675 thermocouple for temperature, then modulates power through PSM (phase-skip with zero-cross detection) and MCPWM (heater duty control).

Highlights

Pressure Control (PID + PSM)

The pressure loop reads the transducer, applies averaging to reduce noise, converts to psi, and feeds the PID controller. The PID output (0–100%) is mapped to PSM levels (0–127) to modulate AC power via zero-cross detection.

// Minimal usage example
pressureCtl.setSetpoint(9.0);            // target = 9 bar
pressureCtl.setCurrentPressure(psiReading);
pressureCtl.update();                     // runs PID and updates PSM

Tip: keep the ISR tiny (zero-cross flag only) and compute in the main loop for stability.

Temperature Control (PID + MCPWM)

The temperature loop reads MAX6675, drives ESP32 MCPWM to control heater duty cycle, and maintains a stable brew temperature.

// Minimal usage example
tempControl::setSetpoint(93.0);          // 93 °C
tempControl::setCurrentTemp(currentC);
tempControl::update();                    // PID compute + MCPWM duty update

OLED User Interface

The OLED (Adafruit SH1106) shows live pressure/temperature, setpoints, and a brewing animation. A rotary encoder provides intuitive navigation; short press to select, rotate to adjust.

Live Demo Web Dashboard

For the capstone demo, we provide a lightweight browser dashboard (GitHub Pages) to visualize telemetry in real time. The page exposes exactly two global functions for the firmware or a small host script to call: init() and update(tempC, psi, tempSetpointC, psiSetpoint). No extra dependencies or build steps.

API

• init() — call once on start (e.g., in setup()).
• update(tempC, psi, tempSetpointC, psiSetpoint) — call periodically (e.g., every 100–250 ms).

Units: tempC/tempSetpointC in °C, psi/psiSetpoint in psi.

// Pseudocode (firmware/host bridge)
  void setup() {
    // ...
    dashboard.init();          // maps to page's init()
  }
  
  void loop() {
    // read sensors + setpoints ...
    dashboard.update(tempC, psi, targetC, targetPsi);
    delay(150);                // update rate for smooth charting
  }

Styling (colors, layout, images) is easily customizable if we want a different look for the poster/demo.

Planned & Future

• Wi-Fi dashboard with live charts
• Data logging and brew profiling
• Advanced flow profiling / pre-infusion

Quick Links

• Home · project overview
• Hardware · wiring, sensors, triac/SSR notes
• FAQ · common questions & troubleshooting
• GitHub Repo