This was found on a window fan remote control. The fan is a Bionaire BW2300

It seems to have no AGC leader, 12 bits, my guess is each bit is either:

  • ~420us on + ~1260us off
  • ~1260us on + ~430us off


  • \$\begingroup\$ Sorry, added info. \$\endgroup\$ – Knio Apr 22 '20 at 18:16
  • 2
    \$\begingroup\$ Are you asking if this is an industry standard protocol? There's no reason any manufacturer has to use a standard, it's pretty easy to transmit data by IR. There's actually good reason NOT to use standards as then your remotes might interfere with each other. In our business, I deal with at least 4 different IC manufacturers, each of which has their own home-brewed protocol. Not saying what you see above is not a standard, just that it very well might not be. \$\endgroup\$ – Kyle B Apr 22 '20 at 19:00
  • 1
    \$\begingroup\$ It's often easier to source a known protocol, like RC-5, NEC or Sony. These are well supported by remote makers like UEI, Remote Solutions, and so forth. But this protocol doesn't look like any of those, though it kind of uses a Manchester-style coding like RC-5. \$\endgroup\$ – hacktastical Apr 22 '20 at 20:36
  • 1
    \$\begingroup\$ @KyleB thanks, that is a reasonable answer. I did not know that custom protocols were relatively common. It looks pretty trivial to decode, but I wanted to know if it was a standard that I had missed before I started. \$\endgroup\$ – Knio Apr 23 '20 at 5:25

the protocol is chinese: the encoder IC is SW5104 by Swsem.com

Function Description

  1. Key input terminals K1—K8 In static mode, the key input terminals K1~K8 are set to high level by the internal pull-up resistor, and in the circuit no current flows; when any key is pressed (that is, grounded), the corresponding programming will be generated.
  2. User code coding bits C1 and C2 In static mode, C1 and C2 are also set to high level by internal pull-up resistors. Users can, if needs, to be set to four different user code combinations.
  3. Data output The generated code is output by the DOUT terminal, please refer to the data output format in the figure below. The following parts are composed:

(1) Start code----1 1 0

(2) User code----C1 C2

(3) Instruction code-7-bit key code signal (for details, please refer to the BEC5104 key code table)

  1. Encoding format

(1) "0": 1/4T high level, 3/4T low level; "1": 3/4T high level, 1/4T Low level

(2) The period of each bit code T = 1.6879ms

(3) The interval between every two frame codes is 4T

When a key is pressed, the LED port outputs high level, after a delay of 32ms, the DOUT port opens. Begin outputting valid data codes. When the button is kept pressed and held, the coded signal will be output continuously. The time interval between each data frame is the length of the 4-bit data code.

  1. Oscillator The internal oscillator of the chip integrates an advanced button start-up power saving mode, when no button is pressed. When the oscillator is in sleep state, no current flows; when a key is pressed, the oscillator starts to work, which saves the power consumption of the system to the greatest extent. When using, it needs to be on the OSC1 and OSC2 ends connect a 455KHz crystal in parallel, please refer to the application circuit for details. SW5104 Key code table

Key code table

NOTE: C1 and C2 are determined by the user. The corresponding bit is "0" if it is floating or grounding. If connected to VDD is "1".

Features and applications

  1. Features • SW5104 adopts 38KHz carrier code transmission, the output has good directionality, anti-interference features such as strong interference ability and long remote control distance. • SW5104 adopts the power-saving mode design of button start-up and low static power consumption. • SW5104 has 8 input channels and 2-digit user code setting keys, so it has 32 different combinations and can produce 32 different encoding outputs for users to choose. • CMOS process design • Wide working voltage range 2.0V~5.0V • Strong ESD resistance

  2. Application • Can be used as a remote control for some household appliances and electric toys (for example, with BEC820XX series decoders are used together as remote control and receiver of electric fan)

• Infrared remote control communication with MCU within a certain distance Application circuit. The following figure is a typical wiring diagram of SW5104 used as an electric fan remote control. When used for other purposes, on the way, according to specific requirements, refer to the wiring diagram to make appropriate adjustments.

IC pinapplication circuittiming of datadata encoding format

  • 2
    \$\begingroup\$ How on earth did you manage to identify this? fine work, either way! Do put a source for your images and anything copied out of a datasheet, though. \$\endgroup\$ – Hearth Oct 4 '20 at 19:26
  • \$\begingroup\$ While this is great information if true; that the nature of the response is "this is what chip X does" demonstrates that the question has never been on topic here, because it is a usage question not a design engineering one. This would have been more properly handled on a forum dedicated to control of existing products. \$\endgroup\$ – Chris Stratton Oct 4 '20 at 22:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.