====== Raspberry Pi Peripherals ======

{| style=""
!
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
|}


===== 1 Wire Interface =====

  * 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

==== Temp. Sensor DS18B20 ====

  * 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

<code>
$ 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
</code>

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]]


===== SPI Interface =====

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


==== MCP3008 10 Bit ADC ====

  * 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]]


==== Waveshare 1.8" LCD Using ST7735 Controller ====

{| style=""
!
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
|}


<code>
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
</code>


**Links:**

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

----

 --- //Martin Burnicki [[martin.burnicki@burnicki.net]] 2018-02-11//