IR Receiver Project on bare-metal Raspberry Pi 4 Model B

The proposed project consists of using an IR receiver to capture commands sent by a remote controller and displaying them on an LCD display, along with the name of the pressed buttons.

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IMPORTANT: A complete overview of the project, including the necessary hardware, is available in documentation.pdf. You should read it before running the project.

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Prerequisites

Your micro SD card must contain the following files:

• bootcode.bin;
• config.txt;
• fixup.dat;
• start4.elf;
• kernel7.img (which contains pijFORTHos);
• bcm2711-rpi-4-b.dtb.

And the config.txt file must contain the following uncommented options:

dtparam=i2c_arm=on
enable_uart=1

which enable the IIC and the UART, respectively.

Connections

Pi 4 Model B	KY-022	FT232RL	IIC PCF8574T
GPIO 25	S
3V3 power	+
GPIO 14 (TXD)		RX
GPIO 15 (RXD)		TX
5V power			VCC
GPIO 2 (SDA)			SDA
GPIO 3 (SCL)			SCL
Ground	-	GND	GND

Code structure

• jonesforth.f : This file contains the word definitions needed for creating strings in memory;

• se-ans.f : This file contains some word definitions for ANSI compliance, created by Professor Daniele Peri;

• utils.f : This file contains general words used throughout the project to manage the reading and, possibly, writing of GPIO pin levels;

• timer.f : This file contains word definitions for reading values from the Raspberry Pi 4 Model B System Timer counter;

• i2c.f : This file contains word definitions to handle the IIC communication with the LCD display;

• lcd.f : This file contains word definitions to print hexadecimal numbers and strings on the LCD, as well as common control commands to clear the display and move the cursor;

• ir_receiver.f : This file contains word definitions that implement the protocol explained in the previous sections to capture commands sent from the remote controller to the IR receiver;

• lookup_table.f : This file contains a simple mapping from the hexadecimal commands sampled by the IR receiver to the corresponding string printed on the pressed buttons;

• main.f : This file contains the main program to be run at startup.

How to run

To run the project, download the repository using

git clone https://github.com/FarInHeight/Embedded-Systems-Project.git

First, using Pi 4, verify the LCD IIC slave address using:

sudo apt-get install i2c-tools
i2cdetect -y 1

and change the slave address in INIT_I2C (contained in i2c.f) accordingly. If you are using a Pi 3 Model B or Model B+, change the constant PERI_BASE in utils.f to 0x3F000000¹.

After that, download picocom and minicom, load pijFORTHos into the micro SD card and change the shell #!/bin/zsh to your shell (also change the python interpreter if needed).

Change the execution permissions as

chmod u+x unify_and_uncomment.py
chmod u+x create_program.sh

and run the script ./create_program.sh.

Finally:

• connect the Pi and the serial UART to your terminal;
• run picocom --b 115200 <your UART> --send "ascii-xfr -sv -l100 -c10" --imap delbs;
• press Ctrl + A and Ctrl + S;
• load the file program.f generated by ./create_program.sh;
• start the program by typing MAIN and pressing Enter.

At this point you can disconnect the UART and enjoy the project.

License

MIT License

Footnotes

1. For the project to work, the boot files must also be changed ↩