X-Git-Url: https://vault307.fbx.one/gitweb/micorpython_ir.git/blobdiff_plain/1c6ed0582600cc85e0b4522148f6082293933507..c1fd11d742e67a6863c8f09c4a181772e371d136:/README.md?ds=sidebyside diff --git a/README.md b/README.md index df2feac..79a90c8 100644 --- a/README.md +++ b/README.md @@ -1,2 +1,120 @@ -# micropython_ir -Nonblocking device drivers to receive from IR remotes and for IR "blaster" apps. +# Device drivers for IR (infra red) remote controls + +This repo provides a driver to receive from IR (infra red) remote controls and +a driver for IR "blaster" apps. The device drivers are nonblocking. They do not +require `uasyncio` but are compatible with it, and are designed for standard +firmware builds. + +The receiver is cross platform and has been tested on Pyboard, ESP8266, ESP32 +and Raspberry Pi Pico. + +In a typical use case the receiver is employed at the REPL to sniff the address +and data values associated with buttons on a remote control. The transmitter is +then used in an application to send those codes, emulating the remote control. + +Other use cases involve running the receiver in an application. This enables an +IR remote to control a device such as a robot. + +## Raspberry Pi Pico note + +Early firmware has [this issue](https://github.com/micropython/micropython/issues/6866) +affecting USB communication with some PC's. This is now fixed. Please ensure +you are using up to date firmware. + +#### [Receiver docs](./RECEIVER.md) + +The transmitter driver is compatible with Pyboard (1.x and D series) and ESP32. +ESP8266 is unsupported; it seems incapable of generating the required signals. + +#### [Transmitter docs](./TRANSMITTER.md) + +# 1. IR communication + +IR communication uses a carrier frequency to pulse the IR source. Modulation +takes the form of OOK (on-off keying). There are multiple protocols and at +least three options for carrier frequency: 36, 38 and 40KHz. + +In the case of the transmitter the carrier frequency is a runtime parameter: +any value may be specified. The receiver uses a hardware demodulator which +should be purchased for the correct frequency. The receiver device driver sees +the demodulated signal and is hence carrier frequency agnostic. + +Remotes transmit an address and a data byte, plus in some cases an extra value. +The address denotes the physical device being controlled. The data defines the +button on the remote. Provision usually exists for differentiating between a +button repeatedly pressed and one which is held down; the mechanism is protocol +dependent. + +# 2. Supported protocols + +The drivers support NEC and Sony protocols plus two Philips protocols, namely +RC-5 and RC-6 mode 0. There is also support for the OrtekMCE protocol used on +VRC-1100 remotes. These originally supported Microsoft Media Center but can be +used to control Kodi and (with a suitable receiver) to emulate a PC keyboard. + +Examining waveforms from various remote controls it is evident that numerous +protocols exist. Some are doubtless proprietary and undocumented. The supported +protocols are those for which I managed to locate documentation. My preference +is for the NEC version. It has conservative timing and good provision for error +detection. RC-5 has limited error detection, and RC-6 mode 0 has rather fast +timing. + +A remote using the NEC protocol is [this one](https://www.adafruit.com/products/389). + +# 3. Hardware Requirements + +These are discussed in detail in the relevant docs; the following provides an +overview. + +The receiver is cross-platform. It requires an IR receiver chip to demodulate +the carrier. The chip must be selected for the frequency in use by the remote. +For 38KHz devices a receiver chip such as the Vishay TSOP4838 or the +[adafruit one](https://www.adafruit.com/products/157) is required. This +demodulates the 38KHz IR pulses and passes the demodulated pulse train to the +microcontroller. + +In my testing a 38KHz demodulator worked with 36KHz and 40KHz remotes, but this +is obviously neither guaranteed nor optimal. + +The transmitter requires a Pyboard 1.x (not Lite), a Pyboard D or an ESP32. +Output is via an IR LED which will need a transistor to provide sufficient +current. The ESP32 requires an extra transistor to work as a transmitter. + +## 3.1 Carrier frequencies + +These are as follows. The Samsung and Panasonic remotes appear to use +proprietary protocols and are not supported by these drivers. + +| Protocol | F KHz | How found | Support | +|:---------:|:-----:|:-------------:|:-------:| +| NEC | 38 | Measured | Y | +| RC-5 RC-6 | 36 | Spec/measured | Y | +| Sony | 40 | Spec/measured | Y | +| MCE | 38 | Measured | Y | +| Samsung | 38 | Measured | N | +| Panasonic | 36.3 | Measured | N | + +# 4. References + +Sources of information about IR protocols. The `sbprojects.net` site is an +excellent resource. +[General information about IR](https://www.sbprojects.net/knowledge/ir/) + +The NEC protocol: +[altium](http://techdocs.altium.com/display/FPGA/NEC+Infrared+Transmission+Protocol) +[circuitvalley](http://www.circuitvalley.com/2013/09/nec-protocol-ir-infrared-remote-control.html) +[sbprojects.net](https://www.sbprojects.net/knowledge/ir/nec.php) + +Philips protocols: +[RC5 Wikipedia](https://en.wikipedia.org/wiki/RC-5) +[RC5 sbprojects.net](https://www.sbprojects.net/knowledge/ir/rc5.php) +[RC6 sbprojects.net](https://www.sbprojects.net/knowledge/ir/rc6.php) + +Sony protocol: +[SIRC sbprojects.net](https://www.sbprojects.net/knowledge/ir/sirc.php) + +MCE protocol: +[OrtekMCE](http://www.hifi-remote.com/johnsfine/DecodeIR.html#OrtekMCE) + +IR decoders (C sourcecode): +[in the Linux kernel](https://github.com/torvalds/linux/tree/master/drivers/media/rc)