nodemcu-firmware/docs/modules/rfswitch.md

# rfswitch Module
| Since  | Origin / Contributor  | Maintainer  | Source  |
| :----- | :-------------------- | :---------- | :------ |
| 2016-12-01 | [Roman Fedorov](https://github.com/ffedoroff) | [Roman Fedorov](https://github.com/ffedoroff) | [rfswitch.c](../../app/modules/rfswitch.c)|


Module to operate 433/315Mhz devices like power outlet sockets, relays, etc. This will most likely work with all popular low cost power outlet sockets with a SC5262 / SC5272, HX2262 / HX2272, PT2262 / PT2272, EV1527, RT1527, FP1527 or HS1527 chipset.

This module uses some code from the [original rc-switch Arduino lib](https://github.com/sui77/rc-switch/) but NodeMCU and Arduino are not fully compatible. This required that **rc-switch** was rewritten into  **rfswitch** NodeMCU with Lua support.

### Connection of transmitter

| Transmitter  | ESP8266  | comments                        |
| :----------- | :------- | :------------------------------ |
| vin or + | 3V3 | 3.3 - 5 volts on ESP8266 or other power source |
| ground or - | GND | ground should be connected to ESP8266 and to power source |
| data pin | 6 | almost any pin on ESP8266 |

You can read more about connection [here](https://alexbloggt.com/wp-content/uploads/2015/10/nodemcu_433_transmitter.png).

### Selecting proper protocol
This module supports **transmitting** data using 6 different protocols
and you should use one most suitable for your needs. **Receiving** data is not supported yet. So, you cannot listen radio air and get protocol details using Lua.

The easiest way to get the correct protocol is to connect the radio receiver to your ESP8266 or [Arduino](https://github.com/sui77/rc-switch/wiki/HowTo_Receive),
then run [ReceiveDemo_Advanced.ino](https://github.com/sui77/rc-switch/blob/master/examples/ReceiveDemo_Advanced/ReceiveDemo_Advanced.ino)
and view output in serial console ([example1](http://www.instructables.com/id/Control-CoTech-Remote-Switch-With-Arduino-433Mhz/?ALLSTEPS),
[example2](http://randomnerdtutorials.com/esp8266-remote-controlled-sockets/)).

You should get something like this:

```
Decimal: 11001351 (24Bit)
Binary: 101001111101111000000111
Tri-State: not applicable
PulseLength: 517 microseconds
Protocol: 5

Raw data: 7200,1004,528,504,1048,980,336,1176,356,1176,352,1180,1108,412,356,1172,364,1168,356,1160,1176,1124,412,336,1180,1116,440,328,1188,340,1228,1060,416,1160,380,1160,1108,464,1068,436,328,1232,1060,412,1116,440,1088,428,3024,
```
More detailed about low level protocol specifications could be found [here](https://github.com/sui77/rc-switch/wiki/KnowHow_LineCoding)
You can visualize a telegram copy the raw data by paste it into [http://test.sui.li/oszi/]()

## rfswitch.send()
Transmit data using the radio module.

#### Syntax
`rfswitch.send(protocol_id, pulse_length, repeat, pin, value, length)`

#### Parameters
- `protocol_id` positive integer value, from 1-6
- `pulse_length` length of one pulse in microseconds, usually from 100 to 650
- `repeat` repeat value, usually from 1 to 5. This is a synchronous task. Setting the repeat count to a large value will cause problems.
The recommended limit is about 1-4. If you need more,
then call it asynchronously a few more times (e.g. using [node.task.post](../modules/node/#nodetaskpost))
- `pin` I/O index of pin, example 6 is for GPIO12, see [details](../modules/gpio/)
- `value` positive integer value, this is the primary data which will be sent
- `length` bit length of value, if value length is 3 bytes, then length is 24

#### Returns
`nil`

#### Example
```lua
-- Lua transmit radio code using protocol #1
-- pulse_length 300 microseconds
-- repeat 5 times
-- use pin #7 (GPIO13)
-- value to send is 560777
-- value length is 24 bits (3 bytes)
rfswitch.send(1, 300, 5, 7, 560777, 24)
```