PV198 - I²C
One-chip Controllers
Daniel Dlhopolček, Marek Vrbka, Jan Koniarik, Oldřich Pecák,
Tomáš Rohlínek, Ján Labuda, Jan Horáček, Matúš Škvarla, Ondřej Bleha,
Martin Klimeš, Adam Valt
Faculty of Informatics, Masaryk University
7/2024
Introduction
I2C
FRDM-K66F I²C
Accelerometer & Magnetometer
Application
Homework
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NXP CUP
International autonomous cars competition (their website)
Working on a group project trying to solve real problems
Diverse set of tasks:
Reading data from various sensors
Designing control algorithm
3D modeling and RC car customization
Our team at last year finals
Contact:
Email: jan.labuda@mail.muni.cz
Discord: Ján Labuda / Northeus
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Introduction
Intro
Switch the branch to Week_07!
Discussion of HW6
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I2C
Embedded communication buses
SPI – Serial Peripheral Interface
I²C – Inter-Integrated Circuit
UART – Universal asynchronous receiver / transmitter
CAN – Controller Area Network
1-Wire
RS-485
RS-232
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I2C
I²C
“eye-squared-C”
I²C = Inter-Integrated Circuit
Invented in 1982 by Philips Semiconductors (now NXP
Semiconductors)
Applications: intra-board communication
Peripherals
Sensors
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I2C
I²C Principle
2 wires
1. SCL – serial clock
2. SDA – serial data
Terminology: controller (= master), target (= slave)
Multi-controller & multi-target
100 kbit/s – 5 Mbit/s
7-bit addressing / 10-bit addressing
Synchronous
Half-duplex
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I2C
I²C Schematic
Source: https://learn.sparkfun.com/tutorials/i2c/all
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I2C
I²C Message
Source: K66 Sub-Family Reference Manual, Figure 58-2.
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I2C
I²C Principles
SCL & SDA are pulled high by pull-up resistors.
ACK bit is set by receiving device (active low for acknowledged).
Master starts with address transmission – if target exists, it will
respond with ACK bit (active low).
Controller then continues in either transmit or receive mode
(according to the read/write bit it sent), and the target continues
in the complementary mode (receive or transmit, respectively).
Bits are sent most significant bit first.
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FRDM-K66F I²C
FRDM-K66F I²C
4 I²C modules
Address match wakeup in low-power modes
SMBus support
DMA support
Functions to use:
BOARD_Accel_I2C_Receive
BOARD_Accel_I2C_Send
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Accelerometer & Magnetometer
Accelerometer & Magnetometer FXOS8700CQ
FXOS8700CQ
Sensor placed directly on FRDM-K66 development board
Datasheet
See 10.1. I²C interface
See 14. Register description
3-axis linear accelerometer + 3-axis magnetometer combined
into a single package
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Accelerometer & Magnetometer
FXOS8700CQ I²C Connection
FXOS8700CQ connected to I²C bus and 2 GPIO pins
FXOS8700CQ K66F Connection
SCL PTD8/I2C0_SCL
SDA PTD9/I2C0_SDA
INT1 PTC17
INT2 PTC13
Source: FRDM-K66F Development Platform User’s Guide, Table 6.
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Application
Seminar task
Create an application that reads accelerometer output data
registers.
Print register values into console.
Bonus
Calculate tilt angle from received values.
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Application
Step-by-step guide
1. Download template from study materials in IS.
2. Look at initializeAccel function implementation, pins
routing & peripherals.
Check if everything is set-up correctly.
3. Read values from sensors in main while loop.
4. Use functions:
BOARD_Accel_I2C_Receive
BOARD_Accel_I2C_Send
5. For now, ignore setupOrientationDetection functions, it
will be used in homework.
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Homework
Homework – Orientation Detection
Create an application that detects orientation of the board (the
same way as mobile phones do).
Use the feature of the sensor – do not calculate it in the MCU
from XYZ register values.
Use interrupt from sensor.
Print current orientation into console when orientation of the
board changes.
Use provided template, write your code into function
setupOrientationDetection.
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