README.md add warning about rp2 USB issue.

[micorpython_ir.git] / README.md

diff --git a/README.md b/README.md
index 44318d546476d17cccac2cbe812d0139d497aead..e2c10d8152d05f871c54492e3fed5a2ac380da20 100644 (file)
--- a/README.md
+++ b/README.md
@@ -5,8 +5,23 @@ 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.
 
 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 and
-ESP32.
+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. It particularly affects code which
+issues `print()` only occasionally: the application appears to have failed. The
+missing messages appear when you press a key. Hopefully this will be fixed soon
+(note dated 8th March 2021).

 
 #### [Receiver docs](./RECEIVER.md)
 
 
 #### [Receiver docs](./RECEIVER.md)
 


@@ -21,12 +36,23 @@ 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.
 
 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
 The drivers support NEC and Sony protocols plus two Philips protocols, namely

-RC-5 and RC-6 mode 0. 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.
+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
 
 Examining waveforms from various remote controls it is evident that numerous
 protocols exist. Some are doubtless proprietary and undocumented. The supported


@@ -37,13 +63,7 @@ timing.
 
 A remote using the NEC protocol is [this one](https://www.adafruit.com/products/389).
 
 
 A remote using the NEC protocol is [this one](https://www.adafruit.com/products/389).
 

-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. Hardware Requirements
+# 3. Hardware Requirements

 
 These are discussed in detail in the relevant docs; the following provides an
 overview.
 
 These are discussed in detail in the relevant docs; the following provides an
 overview.


@@ -60,5 +80,43 @@ 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
 
 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 has significant limitations as a transmitter discussed
-[here](./TRANSMITTER.md#52-esp32).
+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)