README: document project
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README.md
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README.md
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This firmware template is designed for development boards based around [STM32 F4 series micro-controller](https://www.st.com/en/microcontrollers-microprocessors/stm32f4-series.html).
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This is the firmware for the yeast raiser.
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project
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=======
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@ -6,29 +6,96 @@ project
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summary
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-------
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*describe project purpose*
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The purpose is to grow and train a yeast culture in a sourdough started.
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The yeast will multiply on its own, but the optimum temperature is 30 - 35 °C.
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A heater will keep the temperature around 32.5 °C.
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This will also allow to have similar condition to measure the yeast's efficiency over time.
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The device with also monitor the sourdough starter rising under the activity of the yeast.
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technology
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*described electronic details*
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A small glass (e.g. 350 mL) is used to make a sourdough starter.
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board
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=====
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To make a starter:
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The underlying template also supports following board:
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1. mix 50 g of flour and 50g of water (whole wheat flour contains generally more yeast and bacteria since there is more of the grain's shell)
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2. leave it in the glass for 24h
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3. mix 50 g of this starter with 50 g of flour and 50 g of water
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4. repeat from step 2 until the starter is rising twice its original size after a couple of hours
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5. mix 10 g of this starter with 50 g of flour and 50 g of water
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6. leave it for a couple of hours until it's falling back in
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7. you can keep it in the fridge for a couple of days (maximum until a gray liquid layer is forming)
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8. repeat from step 5
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- [WeAct MiniF4](https://github.com/WeActTC/MiniF4-STM32F4x1), based on a STM32F401CCU6
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A heater is used to keep the glass above 30 °C.
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The heater is made out of a lid fitting the glass, so the glass fits perfectly on top of it.
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A 5 Ohm 10 W ceramic resistor is epoxy glued in the lid.
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A DS18B20 sensor is placed next to it to monitor it's temperature.
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The thermometer is used to prevent the lid from over-heating.
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**Which board is used is defined in the Makefile**.
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This is required to map the user LED and button provided on the board
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The top lid of the glass if equipped with the following:
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- a 10 kOhm thermistor in a stainless steel tube, to measure the starter's temperature once plunged into it
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- a HC-SR04 ultrasonic range sensor, to measure the starter's rising
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- a MLX90614 infra-red thermometer, to measure the starter's temperature without contact, as alternative to the thermocouple
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- a n-channel MOSFET, to power the power resistor in the heater
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- a SSD1306 0.96 inch OLED display, to show the starter's temperature and growth
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- a STM32F401-based [WeAct MiniF4](https://github.com/WeActTC/MiniF4-STM32F4x1) development board, to control all peripherals
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To use the yeast raiser:
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1. put the lid on the empty glass
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2. power the board, through the USB-C, USB micro-B, or OD 5.5 mm/ID 2.1 mm barrel jack, using a 5 V 1 A power supply
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3. the screen should display a message
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4. press on the button, which will measure the height of the glass
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5. prepare the sourdough starter in the glass
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6. put back the lid on, inserting the thermistor in the starter
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7. press on the button, which will measure the height of the initial started
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8. the yeast raiser will continuously monitor and display the height and temperature of the sourdough starter
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9. it will heat the starter to 30 - 35 °C, until it falls back
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10. it will show when, and how high the starter was when it reached its peak
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connections
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===========
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Connect the peripherals the following way (STM32F4xx signal; STM32F4xx pin; peripheral pin; peripheral signal; comment):
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Connect the peripherals the following way.
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- *list board to peripheral pin connections*
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button (if not already present on the development board):
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1. ground
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2. PA0
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power n-channel MOSFET:
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1. gate: PB12, pulled up by 100 kO resistor to 5V
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2. drain: power resistor for heated bed
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3. source: ground
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HC-SR04 ultrasonic range sensor:
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1. ground
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2. echo: PB9
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3. trigger: PB8
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4. VCC: 5V
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DS18B20 1-Wire temperature sensor:
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1. ground
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2. 1-Wire: PB10, pulled up by 1 kO resistor to 5V
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3. VCC: 5V
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SSD1306 OLED display module:
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1. gound
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2. VDD: 3.3V
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3. SCK: PB6/I2C1_SCL, pulled up by 10-47 kO resistor to 3.3V
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4. SDA: PB7/I2C1_SDA, pulled up by 10-47 kO resistor to 3.3V
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10 kOhm NTC thermistor:
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1. ground
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2. PA6, pulled to to 3.3V by 10 kOhm resistor
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MLX90614 IR-thermometer:
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1. VIN: 3.3V
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2. GND: ground
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3. SCL: PA8/I2C3_SCL
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4. SDA: PB4/I2C3_SDA
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All pins are configured using `define`s in the corresponding source code.
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