uSonicTimer

ESP8266 · PlatformIOMaintenance onlyGPL-3.0-or-laterCERN-OHL-S-2.0

Firmware for a timer and heater controller I added to a cheap ultrasonic cleaner. A Nokia 5110 LCD shows a menu you drive with a rotary encoder; a DS18B20 sensor watches the bowl temperature, and two solid-state relays switch the heater and the cleaner.

Source on GitHub Send feedback

Mains voltage. The controller switches the 110 VAC bowl heater and the ultrasonic cleaner through solid-state relays. If you build one, treat it with the respect mains deserves. It comes with no warranty.

Inside the enclosure: the blue uSonicTimer V1.0 board from Somerled Design, LLC with its ICSP pogo pads and a green terminal block, two Potter and Brumfield 25 A solid-state relays on the floor, and the power entry module — Inside: the uSonicTimer V1.0 board, two 25 A SSRs and the power entry

The front panel: a square ON-OFF switch, the Nokia 5110 LCD in a yellow 3D-printed bezel, and the rotary encoder shaft — Front panel: ON-OFF switch, Nokia 5110 LCD in a 3D-printed bezel, rotary encoder

What it does

It runs on an ESP8266 (ESP-12E module). The set temperature, timer preset and LCD contrast are saved in (emulated) EEPROM, so they survive a power cycle.

On power-up it loads the settings. Anything unset gets a default: 72 °F, 10 min, contrast 64.
It shows the main menu. Rotate to pick an item; a long press opens it.
Start Timer counts down and runs the bowl:
- while the bowl is more than 10 °F below the set temperature, the heater is on and the cleaner is off;
- once it’s within 10 °F, the heater is off and the cleaner is on;
- at 0, or on a long press, both outputs switch off and the menu comes back.

Rotating moves the highlight, a long press (over 1 s) opens the highlighted item, and a short press toggles the backlight.

Main menu
├── Start Timer   "Time Left: m:ss" / "Temp: <current>F / <set>F"
│                 runs heater/cleaner as above; long press = abort (both outputs off)
├── Set Timer     "Set Timer: <n> min"
│                 rotate = choose preset 3, 8, 10, 15, 20, 30, 60 min (wraps)
│                 press = save to EEPROM and return
├── Set Temp      "Set Temp: ddd F" (3 digits, cursor digit in reverse video)
│                 short press = move cursor; rotate = change digit (0–9, wraps)
│                 long press = save to EEPROM and return
└── Contrast      "Contrast: ddd" (3 digits, cursor digit in reverse video)
                  short press = move cursor; rotate = ±100 / ±10 / ±1 (0–255, live)
                  long press = save to EEPROM and return

The menu approach comes from the educ8s.tv menu tutorial.

Hardware (PCB rev 1d)

Signal	ESP8266 GPIO	Notes
LCD SCLK / DIN	GPIO14 / GPIO13	software SPI
LCD D/C	GPIO1 (TX)	shared with UART TX
LCD CS	GPIO2	10K pull-up
LCD backlight	GPIO15	via Q1, 10K pull-down
Encoder CLK / DT	GPIO16 / GPIO12	CLK polled (no interrupt on GPIO16)
Encoder switch	GPIO3 (RX)	shared with UART RX
Heater SSR / Cleaner SSR	GPIO4 / GPIO5	HIGH = on, NPN low-side drivers
DS18B20 1-Wire	GPIO0	4K7 pull-up; also the program strap

Programming is through five pogo pads (GND, RTS, TX, RX, DTR), with RTS and DTR driving the auto-reset and boot circuit. Because the UART pins double as the LCD D/C line and the encoder switch, the serial output from the debug build shares those lines. The README has the full pin map, with the Arduino and module pin numbers.

Status

Maintenance only.
There’s no tagged release; build it from the source.

Build and flash

It’s a PlatformIO project for the espressif8266 platform, board esp12e, Arduino framework. PlatformIO fetches the libraries (U8g2, ESP Rotary, Button2, OneWire and DallasTemperature) for you.

pio run -e release                  # build the release firmware
pio run -e release -t upload        # flash it over the programming header
pio device monitor -b 115200        # serial monitor (debug build)

platformio.ini keeps the build output under ~/Library/Caches/PlatformIO/uSonicTimer/, out of Dropbox. On a machine that isn’t a Mac, change or remove those two paths.

Feedback

Questions or fixes: please open an issue on GitHub.

License

uSonicTimer has two licences:

The firmware and code are under the GNU General Public License, version 3 or later (GPL-3.0-or-later). See LICENSE.
The hardware design files (the KiCad schematic and PCB, which aren’t in the repo yet) are under the CERN Open Hardware Licence v2, Strongly Reciprocal (CERN-OHL-S-2.0). See LICENSE-HARDWARE.