SPI, UART and Analog Signals

10 Lektionen in dieser Stufe

1. SPI Signals: Clock, MOSI, MISO and Chip Select
   Explain how SPI moves data in both directions at once and what the modes mean. · Lab: Label the four signals on a timing diagram and identify the clock mode.
2. Talking to SPI Devices with spidev
   Enable SPI and exchange bytes with a device from Python. · Lab: Enable SPI and run a loopback test with MOSI wired to MISO.
3. Adding Analog Inputs with an MCP3008
   Wire an ADC and read channels with gpiozero's MCP3008 class. · Lab: Wire the MCP3008 and print the value of a potentiometer as you turn it.
4. Potentiometers, Joysticks and Soil Moisture Probes
   Connect common analog devices and map their output to a useful range. · Lab: Read a joystick on two channels and a soil probe in dry and wet soil.
5. Higher Resolution with an ADS1115 over I2C
   Use programmable gain and differential inputs for small signals. · Lab: Measure a small voltage with the MCP3008 and the ADS1115 and compare the step size.
6. Converting ADC Counts into Real Units
   Apply reference voltage, resolution and a two-point calibration. · Lab: Calibrate the soil probe and a voltage divider against a multimeter.
7. UART Framing: Baud Rate, Start and Stop Bits
   Describe an asynchronous serial frame and what a baud mismatch looks like. · Lab: Decode one printed UART byte by hand at a given baud rate.
8. Freeing the Header UART and the Serial Console
   Configure the serial port for your own devices on Pi 4 and Pi 5. · Lab: Disable the login console on the header UART and loop TX to RX to test it.
9. Reading GPS NMEA Sentences with pyserial
   Parse a stream of serial text into position and time. · Lab: Read a GPS module, extract latitude, longitude and UTC time and log them.
10. Decoding I2C, SPI and UART with a Logic Analyzer
    Capture bus traffic and read it with protocol decoders. · Lab: Capture one BME280 read, one MCP3008 read and one GPS sentence and annotate each.

Abschlussprojekt

A GPS-tagged field logger that samples analog probes through an ADC, records position and time, and whose bus traffic you have verified with a logic analyzer.

Teile für diese Stufe

• 1 × Raspberry Pi 5 or Pi 4 set from Level 1
• 1 × Breadboard and jumper wire set
• 1 × MCP3008 8-channel ADC
• 1 × ADS1115 16-bit ADC module
• 2 × Potentiometer 10 k ohm
• 1 × Analog joystick module
• 1 × Capacitive soil moisture sensor
• 1 × GPS receiver module with UART output
• 1 × USB to TTL serial adapter (3.3 V)
• 1 × USB logic analyzer 8-channel

In jeder Lektion legst du die passenden Teile direkt in den Warenkorb. Raspberry Pi →