IR-Transceiver-SAO

Event badges get lonely too. Why not have them chat with each other?

A Programmable Infrared Multitool SAO. Gives a basic I2C interface to control and request or send data on IR.
Takes care of basic functions such as transmission protocol, processing incoming transmission, and address checking

PCB Build Instructions

• PCB Build Video
  • Note: The buttons on the IR SAO must have the solder bridge soldered closed to be used
    • Warning: Do not solder the solder bridge pads on the bottom of the PCB (QR Code Side) unless you don't have those resistors. Can cause instability issues!
  • Note: The bottom button (next to the ATTiny85) is used as a SAO reset by default. The top button (next to the IR LED/Receiver) is used to trigger a send of the write buffer
• General Project Info
  

Drivers

Want to control the IR SAO with a Hackaday badge?
Use our driver instead of implementing the I2C commands yourself!
MicroPython Driver: https://github.com/DmitryPustovit/MicroPython-IR-Transceiver-SAO

Installation

1. Download this Github
2. Open Visual Studio Code with PlatformIO installed
3. Open this project in the src/main.ino file
4. Setup the ATTINY85 for programming

• This video can be used as hardware connection reference from 2:42 to 8:15. Requires an Arduino Uno

5. Build and Upload using the given platformio.ini

SAO Features

• Public and Address Mode: Two different modes that the IR SAO can automatically sort received IR transmissions
  • Default: Public Mode (mode = 0)
  • Public Mode: The IR SAO ignores the address of incoming IR transmissions. Will save any data of transmissions sent to it
  • Address Mode: The IR SAO will check the address of incoming IR transmissions. Will only save data of transmission with address that match it's IR address
    • IR Address: The 0-255 value address for IR communications.
    • Note: This is not the same as the I2C Address!
    • Note: IR Addresses of received transmissions are not saved on the SAO!
• IR Receive Buffer: An internal buffer in the IR SAO which can save incoming IR transmissions. This buffer is optional, if the buffer is not used, only the last transmission received is saved
  • Default: No IR Receive Buffer (enable_buffer = false)
  • Note: Buffer is 128 Bytes long. Any data received over IR after the buffer is filled is ignored
• IR Transmit Buffer: An internal buffer in the IR SAO which can save IR transmissions to be sent. This buffer is meant to be used to send IR data on button press
  • Warning: This buffer ONLY sends out IR data when the button is pressed. write_ir_byte bypasses this buffer entirely
  • Note: Buffer is 128 Bytes long. Any data sent over I2C after the buffer is filled is ignored
• IR Reflection Ignore: Prevents the receiver from saving any received transmissions with the same IR Address and Data during IR transmission time
  • Default: Ignores Reflections (ignore_ir_reflection = true)

IR Communication Format

The IR SAO default IR Address is 0x00

The IR SAO uses the NEC Transmission Protocol. We use this documentation from Altium as reference
The NEC Transmission Protocol is made up of two main parts, the Address and the Command. The logical inverse of both the Address and Command is also sent allowing for parity checking which is done automatically in the TinyIRReceiver library

• Address: An 8 bit value that specifies the device that should receive the transmission
• Command: An 8 bit value that specifies data. The format of this data is unspecified, it can be anything the user desires
• Note: The TinyIRReceiver Library also supports Extended NEC Protocol, Onkyo, and FAST but are not used in this code!

I2C Communication Format

The IR SAO default I2C Address is 0x08

Communications are made up of two parts. The first is the command and the second is the parameter(s). The Command is always sent first and the parameter(s) are sent subsequently as needed per command. Commands do not return any acknowledgement

• Command - uint8_t: Determines what action you would like for the IR SAO. List of commands below
• Parameter(s) - uint8_t[]: Extra data specifiec by each command. Separated in uint8_t chunks

I2C Example Communications

• To change the address of the IR SAO to address 8, the master should send:
  0x04 0x08
  
• To read a byte from the IR SAO, the master should send:
  0x08
  The master would then request a byte back and be sent back a received IR byte such as:
  0x69
• To send a byte of value 50 to the IR address of 230 over IR from the IR SAO, the master should send:
  0x09 0xE6 0x32

I2C Command API

ping

Description: Debug command to sanity check
Command Value: 0x00
Parameters: None
Output: None

set_ignore_ir_reflection

Description: Sets the receiver if it should or shouldn't ignore messages that were reflected from
Command Value: 0x01
Parameters: A uint8_t value of 0 or 1. 0 disables the check for ignoring IR reflections while 1 enables it. Other values are ignored
Output: None

set_ir_mode

Description: Sets the send/receive mode of the IR system
Command Value: 0x02
Parameters: A uint8_t value of 0 or 1. 0 puts the SAO in public mode while 1 puts it in address mode. Other values are ignored
Output: None

enable_ir_buffer

Description: Enables or disables the ability to buffer IR data on the ATTINY85. Note: clears the receive buffer when this is changed
Command Value: 0x03
Parameters: A uint8_t value of 0 or 1. 0 disables the receive buffer while 1 enables it. Other values are ignored
Output: None
Note: Clears the IR receive buffer when command is sent no matter what the new mode value is

set_ir_address

Description: Sets the IR address of this ATTINY85
Command Value: 0x04
Parameters: A uint8_t value between 0 and 255. This value represents the IR address of the SAO
Output: None

get_ir_address

Description: Send the IR address of this ATTINY85 over I2C
Command Value: 0x05
Parameters: None
Output: Returns a uint8_t value between 0 and 255. This value represents the IR address of the SAO

clear_ir_receive_buffer

Description: Clears the IR Receive Buffer
Command Value: 0x06
Parameters: None
Output: None

get_ir_receive_buffer_avaliable

Description: Get the number of bytes in the IR Receive Buffer
Command Value: 0x07
Parameters: None
Output: Returns a uint8_t value between 0 and 255. This value represents the number of bytes in the IR receive buffer
Note: Will still return 0 or 1 if the IR receive buffer is disabled

read_ir_byte

Description: Send a byte from the IR Buffer. Bytes come in FIFO ordering. Buffer is left shifted with zeros
Command Value: 0x08
Parameters: None
Output: Returns a uint8_t value between 0 and 255. Value is received IR data in the received IR buffer
Note: It is not guarenteed that there will be a byte sent! Use get_ir_receive_buffer_avaliable to make sure there is a byte to read, otherwise nothing will get sent over I2C!

write_ir_byte

Description: Send a byte out over IR. The first received i2c byte is the address and the second is the data
Command Value: 0x09
Parameters: Two uint8_t values between 0 and 255. The first value represents the IR address and the second represents data that will be transmitted
Output: None

write_to_ir_write_buffer

Description: Write a byte to the write buffer that can be trigger send over IR. The first received i2c byte is the address and the second is the data
Command Value: 0x10
Parameters: Two uint8_t values between 0 and 255. The first value represents the IR address and the second represents data that will be transmitted
Output: None
Note: Write buffer will stay populated until clear command is called. Default size of the buffer is 16 bytes.

Samples

A few samples provided to test various functions of the SAO

• Upload_Test: A LED Blink sketch which blinks an LED on Pin_PB2 of the ATTiny85
• I2C_Test: A I2C testing sketch which tests slave functionality on the ATTiny85
  • Note: The I2C Host sketch can be used as the I2C Master. Intended to be used with an Arduino Uno
• IR_Test: A IR LED and Receiver testing sketch which tests address and data sending and receiving on the IR SAO. Turns an LED on Pin_PB2 if the received IR signal has the correct address and data
• Receiver_Signal: A IR Test sketch which uses the IRremote library to test IR sending and receiving, displaying results through serial
• Tiny_Receiver_Button_Send: A IR Test sketch which uses the TinyIRReceiver library to test IR sending based on button input
• Tiny_Receiver_Signal_Info: A IR Test sketch which uses the TinyIRReceiver library to test IR receiving

ATTiny85 Pinout

Libraries Used

• ATtinySerialOut
• Arduino-IRremote