The I2C Bus

10 Lektionen in dieser Stufe

1. How I2C Shares Two Wires Among Many Devices
   Describe addressing, start and stop conditions and acknowledge bits. · Lab: Decode a printed I2C waveform by hand into address, direction and data bytes.
2. Enabling I2C and Scanning the Bus with i2cdetect
   Turn on the interface and confirm a device answers at its address. · Lab: Enable I2C, wire a BME280 and find it with i2cdetect -y 1.
3. Reading a BME280 with a Ready-Made Library
   Install a driver library in a venv and get calibrated readings. · Lab: Print temperature, humidity and pressure once a second and sanity-check them.
4. Reading Registers Directly with smbus2 and a Datasheet
   Find a register in a datasheet and read it without a driver library. · Lab: Read the BME280 chip-ID register and one raw data register with smbus2.
5. Bytes, Bits and Two's Complement for Sensor Data
   Combine bytes into signed values and apply masks and shifts. · Lab: Convert raw two-byte readings into signed integers and verify against known values.
6. Several Devices on One Bus and Address Conflicts
   Plan addresses and resolve clashes with address pins or a multiplexer. · Lab: Run two identical sensors on one bus through a TCA9548A.
7. Pull-Ups, Cable Length and Bus Speed
   Choose pull-up values and bus speed for a reliable link. · Lab: Extend the bus with a one-metre cable and find the speed at which errors begin.
8. Motion Data from an MPU6050 Accelerometer and Gyro
   Read acceleration and rotation and convert them into physical units. · Lab: Print tilt angle from the accelerometer and detect a tap.
9. Keeping Time with a DS3231 and the Pi 5 Onboard RTC
   Hold correct time without a network on Pi 4 and Pi 5. · Lab: Fit the Pi 5 RTC battery or a DS3231, disconnect the network and verify time after a power cycle.
10. Diagnosing I2C Faults: NACKs, Stuck Buses and Wrong Voltages
    Find the cause when a device does not appear or returns errors. · Lab: Diagnose three prepared faults: swapped wires, missing ground and a 5 V-only module.

Abschlussprojekt

A multi-sensor environmental node that reads climate and motion data over one I2C bus and keeps correct timestamps with no network.

Teile für diese Stufe

• 1 × Raspberry Pi 5 or Pi 4 set from Level 1
• 1 × Breadboard and jumper wire set
• 1 × BME280 temperature, humidity and pressure module (3.3 V)
• 1 × MPU6050 accelerometer and gyro module
• 1 × DS3231 real-time clock module
• 1 × RTC backup battery for the Pi 5
• 1 × TCA9548A I2C multiplexer module
• 1 × Bidirectional logic level converter 4-channel
• 1 × Resistor kit including 4.7 k ohm

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