build a program remote control ir transmitter using ht6221

7/30/2019 Build a Program Remote Control IR Transmitter Using HT6221

1/4

Build A Program Remote Control IR

Transmitter Using HT6221/HT6222 IC

Program Remote Control IR Transmitter

This project is based on integrated circuit from HoltekSemiconductorHT6221/HT6222. Similarparts used to be produced by NEC Semiconductor uPD6121/uPD6122. These ICs are commonly

used intelevisionand VCR infra red remote controls, garage door controllers, car door

controllers, security systems and other remote controlapplications.

They are capable of encoding 16-bit address codes and 8-bit data codes. Each address/data input

can be set to one of the two logic states, 0 and 1. The HT6221 can have keys up to 32(K1~K32)and HT6222 64 keys (K1~K64). When one of the keys is triggered, the programmed

address/data is transmitted together with the header bits via an IR (38kHz carrier) transmissionmedium.

This project provides thetransmitterpart of the remote control. Designers and hobbyists will

have to do their ownsoftwareat the receiver board. Those who are familiar with microcontrollerprogramming will find this device easy to use. The features of this IC are:

Operatingvoltage: 1.8V to 3.5V DCData output with 38kHz carrier for IR medium

Low standby current

455kHz ceramic resonator or crystal

16-bit address codes8-bit data codes

Pulse Position Modulation code method

Program Remote Control Circuit Description
http://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.htmlhttp://www.electronics-project-design.com/ProgramRemoteControl.html


2/4

Program Remote Control Circuit Description

The typical 32 pins HT6221 schematic is as shown above. However, the values of 1k ohm and47 ohm at the output pin 5 of the IC can be reduced to increase the distance the IR signal is

transmitted. After the transmission codes are sent, the DOUT pin generates transmission codes

with a carrier, and the LED goes low to drive a transmission indicator.


3/4

When one of the keys is triggered for over 36ms, the oscillator is enabled and the chip is

activated. If the key is pressed and held for 108ms or less, the 108ms transmission codes are

enabled and comprised of a header code (9ms), an off code (4.5ms), low byte address codes(9ms-18ms), high byte address codes (9ms-18ms), 8-bit data codes (9ms-18ms), and the inverse

codes of the 8-bit data codes (9ms-18ms).

After the pressed key is held for 108ms, if the key is still held down, the transmission codes turn

out to be a composition of header (9ms) and off codes (2.5ms) only.

Logic 0 is represented by timing 1.12ms and logic 1 by timing 2.24ms using pulse position

modulation method as shown below.


4/4

The address code and data codes are set using the diodes 1N4148 and resistors 51K ohm and

whether D7 is connected to Vcc or Ground.

The complete specifications of the Program Remote Control IC HT6221/HT6222 can be

downloaded here.
http://www.electronics-project-design.com/support-files/6221specs.pdfhttp://www.electronics-project-design.com/support-files/6221specs.pdfhttp://www.electronics-project-design.com/support-files/6221specs.pdfhttp://www.electronics-project-design.com/support-files/6221specs.pdf

build a program remote control ir transmitter using ht6221

Documents