Raspberry Pi Peripherals

Device	Conn. / Type	Interface
Temp. Sensor DS18B20	Chip	1 Wire Interface
MCP3008 10 Bit ADC	Chip	SPI Interface
Waveshare 1.8" LCD Using ST7735 Controller	Chip	SPI Interface
Ultraschall-Abstandssensor	4-pol.	GPIO
Relais 1x 250V / 10 A	Grove 4-pol.	???
Relais 2x 250V / 10 A	4-pol.	GPIO
Temperature & Humidity	Grove 4-pol.	???
Bodenfeuchtigkeit / Moisture	Grove 4-pol.	Analog

• RaspBian Stretch: Enable Interface by running sudo raspi-config
• Module w1_gpio is loaded automatically
• Some other modules are loaded automatically if a well-known device is detected
• GPIO4 / Pin 7 is used for 1 wire data

• 3.3 V operation
• Module w1_therm is loaded automatically if a DS18B20 compatible device is detected
• Detected devices are listed below /sys/bus/w1/devices/
• For each DS18B20 compatible device a link to a subdirectory is created with name 28-*, e.g. 28-03177144feff
• The device subdirectory contains a text file w1_slave that returns the data read when the file is read

$ cat 28-0000092bd91e/w1_slave 
58 01 4b 46 7f ff 08 10 f9 : crc=f9 YES
58 01 4b 46 7f ff 08 10 f9 t=21500

where crc=.. YES incicates that the data CRC is OK, and t= is the temperature in 1/1000 °C

Links:

• Jürgen Plate: Raspberry Pi: 1-Wire Temperatursensor DS1820
  http://www.netzmafia.de/skripten/hardware/RasPi/Projekt-Onewire/index.html

• MOSI: Master Out Slave In (data output from master)
• MISO: Master Master In Slave Out (data output from slave)

• 2.7V - 5.5V operation
• Connect to SPI0 with CS0 –> SPI0.0
• Edit /boot/config.txt and add line dtoverlay=mcp3008:spi0-0-present.
  This loads module mcp320x, which also supports the MCP3008.
• Once the module is loaded the device appears under /sys/bus/iio/devices/iio\:
• Read channel 0: cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw

Links:

• Using MCP3008 ADCs with Raspberry Pis
  http://www.jumpnowtek.com/rpi/Using-mcp3008-ADCs-with-Raspberry-Pis.html

• Interfacing an SPI ADC (MCP3008) chip to the Raspberry Pi using C++ (spidev)
  http://hertaville.com/interfacing-an-spi-adc-mcp3008-chip-to-the-raspberry-pi-using-c.html

Pin	Raspi GPIO	Signal	Cable Color
VCC	+3.3 V	Power Supply	violet
GND	GND	Ground	white
DIN	MOSI		green
CLK	SCLK		orange
CS	SPI0 CS0		yellow
DC	GPIO24	Command / Data	blue
RST	GPIO25	Reset	black
BL	+5V?		red

sudo modinfo fbtft_device  # list module parameters

sudo modprobe fbtft_device name=sainsmart18 busnum=1    # Use SPI0 CS1 instead of SPI0 CS0
sudo modprobe fbtft_device name=sainsmart18 speed=16000000
sudo modprobe fbtft_device name=sainsmart18 speed=16000000 rotate=270

Links:

• ST7735 + Raspberry Pi (framebuffer) (Video)
  https://www.youtube.com/watch?v=AbCuPrYhETw

— Martin Burnicki martin.burnicki@burnicki.net 2018-02-11