I2CStepper

Extending the capabilities of Samovar with the additional I2CStepper board with a stepper motor and four relays.

The module can be used as a standalone device. It can be controlled on its own with the menu on a 16x2 LCD screen and an encoder, or while connected to Samovar.
The expander is connected to Samovar over the I2C bus with four wires (like the LCD screen). Samovar detects that the expander is connected and can control it.

 

Samovar 7.00: the firmware works with the boards using protocol version 3. Up to ten boards with I2C addresses from 1 to 10 can be on the bus: boards with an odd address (1, 3, 5…) are stirrers, boards with an even address (2, 4, 6…) are pumps (continuous pumping or filling a set volume). Each board tells Samovar what it can do: stirrer, pumping, filling, relays, external sensor. The boards are searched for when Samovar starts and are then polled in the background; if at least one is found, an "I2CStepper" button appears on the main page of every mode and opens the board control page. A board that has once responded on the bus stays in the list until Samovar is rebooted; if communication with it is lost, it is marked as unavailable.

During operation (rectification program, Lua, Beer and Cheese modes) Samovar uses one working stirrer and one working pump — the boards with the lowest address among those found. They are fixed when the process starts and do not change until it ends, even if a board with a lower address appears during the run.

In Beer mode the first relay is used to switch the wort transfer pump on and off (for example, to circulate the wort in the brew kettle). The firmware does not use the other relays — you decide what they do, and you can switch them from Lua. The relays are served by the working stirrer if it has declared relay support, otherwise by the working pump.

The board settings themselves (mode, speed, stirrer run time and pause, pump flow, fill volume and rate, steps per milliliter) are stored in the Nano memory and edited on the Settings → I2CStepper tab («Настройки → I2CStepper»), see below. The "I2CStepper" page is used only for manual start and stop.

 

The "I2CStepper" page: the pump board with address 2 is selected

 

If two or more boards are found, a "Device" («Устройство») list appears at the top — use it to choose the board you work with: "Stirrer, address N" («Мешалка, адрес N») or "Pump, address N" («Насос, адрес N»). With a single board the list is hidden. If the selected board is unavailable, the message "The selected I2CStepper is unavailable" («Выбранный I2CStepper недоступен») is shown instead of the panel — another board is not substituted automatically, you have to choose it in the list.

For the selected board the page shows its type and address, its state ("Running" («Работает») or "Stopped" («Остановлен»)), the current speed in steps per second and how many steps are left before it stops. The data is refreshed every two seconds.

Control. "Speed" («Скорость») is the motor speed in steps per second (from 1 to 18000), "Target, steps" («Цель, шагов») is how many steps to make. The "Run" («Запустить») button sends these two values to the board and starts the motor in the mode stored in the Nano memory: for a stirrer it is rotation, for a pump it is filling with the given number of steps. For a pump it is easier to calculate the number of steps from the volume: multiply the required milliliters by "Steps/mL" («Шагов/мл») from the Nano settings. "Stop" («Стоп») stops the motor. The start is impossible if the pump is not calibrated ("Steps/mL" is zero) or Samovar is switching its mode at that moment — an error message is shown then.

Relays. If the board has declared relay support, a "Turn relay 1 on" («Включить реле 1») / "Turn relay 1 off" («Выключить реле 1») button is shown — it switches the first relay of the board (in Beer mode this is the wort pump). Relays 2–4 cannot be switched from this page, only from Lua.

External pump calibration. The button is available only for pump boards that support filling. It opens the calibration page for the selected board: prepare a measuring container, set the motor speed and press "Start calibration" («Начать калибровку») — the pump starts pumping. When exactly 100 mL has been collected, press "Set 100 mL" («Зафиксировать 100 мл»): Samovar calculates "Steps/mL" and writes the value to the Nano memory. Repeat the calibration after changing the driver microsteps, the motor, the pump head or the tubing.

 

Settings → I2CStepper. The "Nano I2CStepper settings" («Настройки Nano I2CStepper») tab shows the settings stored in the memory of the board itself. The "Rescan I2C devices" («Пересканировать I2C-устройства») button searches the bus for boards again (for example, after connecting a new one). If there are several boards, choose the one you need in the "Device" list. Fields:

The "Save to Nano" («Сохранить в Nano») button writes the fields to the non-volatile memory of the board; they survive a restart of both Samovar and the board.

Settings → Pump («Настройки → Насос»). If an I2C pump is found, two fields for rectification appear on the tab:

The speed in liters per hour for this pump is converted into steps using "Steps/mL" from the Nano memory; the separate "I2C pump steps count" («Количество шагов I2C насоса») field no longer exists in the Samovar settings.

 

The Samovar apps and the Samovar control page on the samovar-tool.ru website receive the list of boards and their state (availability, mode, speed, remaining amount, relay mask) every five seconds and let you start and stop a board and switch the relays. The Nano settings and calibration are not available through the apps — only through the Samovar web interface. If a command is rejected, the reason arrives in the Samovar messages in the form "Blynk V37 a=N: code" («Blynk V37 a=N: код»).

 

 

 

 

 

 

 

 

 

 

 

 

The functions are available when the firmware is built with Lua (see About the Lua scripting language). The stirrer functions work with the working stirrer, the pump functions with the working pump (the boards with the lowest address, see above). All start functions return 1 if the command was accepted by the board and 0 if not — including when the required board is not on the bus.

Example: set_stepper_by_time(800, 0, 0) – rotate the stirrer continuously at 800 steps per second; set_stepper_by_time(0, 0, 0) – stop it. i2cpump_start(6, 250) – pump 250 mL at 6 L/h; while i2cpump_get_running() == 1, the pump is running.