I2C in Depth: Sharing Two Wires Among Many Chips

10 Lektionen in dieser Stufe

1. I2C Bus Electricals: Open Drain, SDA, SCL and Pull-Ups
   Explain why devices only pull lines low and how pull-up resistors set the high level. · Lab: Measure idle bus voltage and find the pull-ups already fitted on your modules.
2. Addresses, Start, Stop and ACK on the Logic Analyzer
   Recognise the elements of a transaction in a capture. · Lab: Capture a bus scan and identify which address was acknowledged.
3. Wire Library Transactions: Writing and Reading Registers
   Perform write, read and repeated-start sequences with the Wire library. · Lab: Read the identification register of a sensor and print it in hex.
4. Driving a Sensor from Its Register Map without a Library
   Use a datasheet register table to configure and read a device yourself. · Lab: Wake an MPU-6050 and read raw acceleration with your own functions.
5. Tilt Angles from an MPU-6050 Accelerometer and Gyroscope
   Convert raw values to angles and blend both sensors with a simple complementary filter. · Lab: Show pitch and roll and compare accelerometer-only with the filtered angle while shaking.
6. Pressure, Temperature and Altitude with a BME280
   Read a calibrated environmental sensor and derive altitude change. · Lab: Measure the height difference between floor and table or between two storeys.
7. Keeping Time with a DS3231 Real-Time Clock
   Set, read and use a battery-backed clock and its alarm output. · Lab: Set the clock, unplug the board for a minute and confirm time is kept.
8. More Pins with a PCF8574 Port Expander
   Add inputs and outputs over the bus and understand quasi-bidirectional pins. · Lab: Drive four LEDs and read two buttons through the expander.
9. Address Conflicts and the TCA9548A Multiplexer
   Resolve identical addresses with address jumpers or a bus multiplexer. · Lab: Run two identical OLED displays showing different content through the multiplexer.
10. Bus Speed, Cable Length and Recovering a Stuck Bus
    Choose clock speed and pull-up values for a given wiring and free a bus held low. · Lab: Lengthen the bus until errors appear, then fix it with stronger pull-ups and lower speed.

Abschlussprojekt

A battery-backed clock and weather display combining real-time clock, pressure sensor, motion sensor and OLED on one bus.

Teile für diese Stufe

• 1 × UNO-compatible board
• 1 × USB cable matching the board
• 1 × Solderless breadboard 830 points
• 1 × Jumper wire set male-male and male-female
• 1 × USB logic analyzer 8 channel
• 1 × MPU-6050 accelerometer and gyroscope module
• 1 × BME280 pressure, humidity and temperature module
• 1 × DS3231 real-time clock module with battery
• 1 × PCF8574 port expander module
• 1 × TCA9548A I2C multiplexer module
• 2 × OLED display 0.96 inch I2C 128x64
• 4 × Resistor 4.7 kilohm
• 1 × Bidirectional logic level shifter module
• 4 × LED 5 mm assorted
• 4 × Resistor 220 ohm
• 2 × Tactile push button

In jeder Lektion legst du die passenden Teile direkt in den Warenkorb. Arduino-kompatibel →