| No. | PIN | Connector – PIN – Device | Purpose |
| 1 | VIN | 5V power – input | |
| 2 | GND | ground (GND) | |
| 3 | D13 | 4CHRELE – Relay No. 4 | RM2M Boost |
| 4 | D12 | SG1 – Speaker | Sound, alerts |
| 5 | D14 | 4CHRELE – Relay No. 3 | Control of the cooling water supply valve (open/close). The water valve opens when the boiler temperature set in the sketch is reached and closes when the power is turned off. |
| 6 | D27 | Level – Reflux sensor | Reflux level |
| 7 | D26 | U3 – STEP – Stepper driver | Stepper motor control |
| 8 | D25 | SERVO1 Servo drive | Take-off unit control |
| 9 | D33 | U3 – EN – Stepper driver | Stepper motor control |
| 10 | D32 | U3 – DIR – Stepper driver | Stepper motor control |
| 11 | D35 | ALARM_BTN | Emergency button. Pressing it stops the water supply and cuts the power. You can use it with leak sensors (several can be connected in parallel) or with an ordinary button (which can also be connected in parallel with the leak sensors). It is disabled in the sketch by default. You need to uncomment //#define USE_ALARM_BTN And pull D35 up to 3.3V with a 10k resistor |
| 12 | D34 | LUA_PIN | The port is reserved for working with scripts. It can be used to read an analog or a digital signal. |
| 13 | D39 | BTN – Button | In distillation mode it starts/stops the process. In rectification mode it starts boost, starts programs, pauses take-off (depends on the current Samovar status) |
| 14 | D36 | WATERSENSOR – flow sensor | Water flow monitoring |
| 15 | EN | NO | |
| 16 | D23 | ENC1 – KEY – Encoder button | Encoder, select |
| 17 | D22 | BME(BMP) – SCL + LCD1 -SCL | Atmospheric pressure sensor + display |
| 18 | TX0 | NO | |
| 19 | RX0 | NO | |
| 20 | D21 | BME(BMP) – SDA + LCD1 -SDA | Atmospheric pressure sensor + display |
| 21 | D19 | ENC1 – S2 | Encoder |
| 22 | D18 | ENC1 – S1 | Encoder |
| 23 | D5 | DS1280 – Temperature sensors | Temperature sensor monitoring |
| 24 | TX2 | UART – TX | Heating stabilizer control |
| 25 | RX2 | UART – RX | Heating stabilizer control |
| 26 | D4 | SERVO2 – Cooling pump PWM | Used for PWM control of the cooling pump, if one is connected (selected in the sketch), or of the water regulating/bypass valve, if no water pump is used (PWM). In both cases the water temperature set in the sketch is maintained. |
| 27 | D2 | 4CHRELE – Relay No. 1 | Contactor (on – when heating is on, off – when heating is off), or control of the RM2M – on/off |
| 28 | D15 | 4CHRELE – Relay No. 2 | In “Beer” mode it is used to switch the stirrer on |
| 29 | GND | ground (GND) | |
| 30 | 3V3 | 3.3V power – output |
