Sun drying emulation controller for biltong and other dried foodstuffs, based around STM32G070 series controller.
Intended to be used with drying enclosures like biltong-boxes to produce sun-dried foods in non-ideal climates.
Biltong board is composed of 4 separate PCBs: a main driver board, a UI/control deck board, and 2 identical temperature + humidity sensor breakout boards.
The schematics and layout files for all boards can be found within the hardware directory of this repo, in the form of KiCad 7.0 projects.
The key features of each board:
Main board:
- Interfaces to drive sensor breakout boards, the control deck board, heat lamps, and +12V PC fans.
- Stand alone power supply, no DC adapter required.
- A magnetically isolated current sensor for linearizing the response of the triac based heat-lamp dimmer circuit.
- A low speed oscillator and coin-cell battery interfaced to STM32's RTC for time keeping during power loss.
- A normally open safety relay to remove the lamps from circuit.
- IO expansion header, with unused GPIO for development of new features or debugging.
- Extra mounting holes for safety cover, to prevent mishaps with high voltage side of board.
UI/control deck board:
- An SPI based SH1122 driven OLED display for indicating information to the user.
- 3 navigation buttons for user input.
- A buzzer to notify user attention is required.
Sensor Breakout Board:
- I2C based temperature and humidity sensor from Würth Elektronik for closing loop between fans and lamps.
| SIGNAL | PIN # | GPIO# | PERIPHERAL | DESCRIPTION |
|---|---|---|---|---|
| DISP_SCL | 12 | PA1 | SPI1 | SH1122 display SPI clock signal. |
| I2C1_SDA | 32 | PA10 | I2C1 | Temp & humidity sensor A I2C data signal. |
| I2C2_SCL | 33 | PA11 | I2C2 | Temp & humidity sensor A I2C clock signal. |
| I2C2_SDA | 34 | PA12 | I2C2 | Temp & humidity sensor B I2C data signal. |
| DISP_MOSI | 13 | PA2 | SPI1 | SH1122 display SPI data signal. |
| SW_UP | 14 | PA3 | GPIO | Active low user up navigation button signal. |
| SW_ENTER | 15 | PA4 | GPIO | Active low user enter/select navigation button signal. |
| SW_DOWN | 16 | PA5 | GPIO | Active low user down navigation button signal. |
| FAN_B_PWM | 17 | PA6 | TIM16_CH1 or TIM3_CH1 | Fan B PWM signal. |
| FAN_B_TACH | 18 | PA7 | GPIO or TIM17_CH1 or TIM14_CH1 | Fan B tachometer signal. |
| I2C1_SCL | 29 | PA9 | I2C1 | Temp & humidity sensor B I2C clock signal. |
| FAN_A_TACH | 19 | PB0 | GPIO or TIM3_CH3 | Fan A tachometer signal. |
| FAN_A_PWM | 20 | PB1 | TIM14_CH1 | Fan A PWM signal. |
| UART_TX | 22 | PB10 | USART3 | Serial console UART TX signal for development. |
| UART_RX | 23 | PB11 | USART3 | Serial console UART RX signal for development. |
| I_SENSE | 21 | PB2 | ADC_IN10 | Heat lamp current sensor output, analog signal from 0 -> vcc/2 (0A) ->vcc. |
| ZERO_CROSS | 40 | PD2 | GPIO | Live/mains signal for sine wave zero cross detection (triac shut off point). |
| BUZZ | 45 | PB6 | GPIO or TIM1_CH3 or TIM16_CH1N | Buzzer alarm signal, frequency modulated PWM. |
| DISP_CS | 46 | PB7 | GPIO | SH1122 display SPI chip select signal. |
| DISP_DC | 47 | PB8 | GPIO | SH1122 display data/!command signal, held low for data, high for commands. |
| DISP_RES | 48 | PB9 | GPIO | SH1122 display reset signal. |
| TRIAC_TRIG | 42 | PB3 | GPIO | Triac dimmer trigger, single pulse enables triac until instantaneous AC voltage crosses 0V. |
| HEAT_LAMP_EN | 43 | PB4 | GPIO | Normally open heat lamp saftey relay enable. When held high heat lamp circuit is closed. |
See myles-parfeniuk/wsen_hids_breakout.
See myles-parfeniuk/wsen_hids_breakout.
See myles-parfeniuk/wsen_hids_breakout.
The firmware is currently being developed. This repo will updated as work is completed.
Distributed under the GPL-3.0 License. See LICENSE.md for more information.
Myles Parfeniuk - myles.parfenyuk@gmail.com
Project Link: myles-parfeniuk/biltong_board