Add MCE. Fix bug with RC5X.

[micorpython_ir.git] / TRANSMITTER.md

diff --git a/TRANSMITTER.md b/TRANSMITTER.md
index 8a8331414ee1d726e1ddb87e1ec0b40da2ff1211..4f15c656e190e56494ff0a6f3f76593f7a3bf445 100644 (file)
--- a/TRANSMITTER.md
+++ b/TRANSMITTER.md
@@ -31,19 +31,19 @@ The transistor type is not critical.
 
 The driver assumes circuits as shown. Here the carrier "off" state is 0V,
 which is the driver default. If using a circuit where "off" is required to be
 
 The driver assumes circuits as shown. Here the carrier "off" state is 0V,
 which is the driver default. If using a circuit where "off" is required to be

-3.3V, the constant `_SPACE` in `ir_tx.__init__.py` should be changed to 100.
+3.3V, the class variable `active_high` should be set `False`.

 
 ## 1.2 ESP32 Wiring
 
 The ESP32 RMT device does not currently support the carrier option. A simple
 hardware gate is required to turn the IR LED on when both the carrier pin and
 
 ## 1.2 ESP32 Wiring
 
 The ESP32 RMT device does not currently support the carrier option. A simple
 hardware gate is required to turn the IR LED on when both the carrier pin and

-the RMT pin are high. A suitable circuit is below.  
+the RMT pin are high. A suitable circuit is below; the transistor type is not
+critical.  

 ![Image](images/gate.png)
 
 ![Image](images/gate.png)
 

-The transistor type is not critical. A gate could be built with two similarly
-connected N-channel MOSFETS. The 1KΩ resistors would not be required. The
-MOSFETS would require a low RDSon at Vgs == 3.3V. A ZVN4210A seems suitable
-but I haven't tried it.
+This simpler alternative uses MOSFETS, but the device type needs attention. The
+chosen type has a low gate-source threshold voltage and low Rdson.  
+![Image](images/gate_mosfet.png)

 
 # 2. Dependencies and installation
 
 
 # 2. Dependencies and installation
 


@@ -60,7 +60,11 @@ from [this repo](https://github.com/peterhinch/micropython-async).
 ## 2.2 Installation
 
 The transmitter is a Python package. This minimises RAM usage: applications
 ## 2.2 Installation
 
 The transmitter is a Python package. This minimises RAM usage: applications

-only import the device driver for the protocol in use.
+only import the device driver for the protocol in use. Clone the repository to
+the current directory of your PC with:
+```bash
+$ git clone https://github.com/peterhinch/micropython_ir
+```

 
 Copy the following to the target filesystem:
  1. `ir_tx` Directory and contents.
 
 Copy the following to the target filesystem:
  1. `ir_tx` Directory and contents.


@@ -102,8 +106,18 @@ occurs as a background process, on the Pyboard controlled by timers 2 and 5.
 Execution times on a Pyboard 1.1 were 3.3ms for NEC, 1.5ms for RC5 and 2ms
 for RC6.
 
 Execution times on a Pyboard 1.1 were 3.3ms for NEC, 1.5ms for RC5 and 2ms
 for RC6.
 

+Class variable:
+ 1. `active_high=True` Normally the IR LED drive circuit turns the LED on if
+ the pin goes high. If it works with the opposite polarity the variable should
+ be set `False` before instantiating.
+

 #### NEC class
 
 #### NEC class
 

+Class `NEC`. Example invocation:
+```python
+from ir_tx.nec import NEC
+```
+

 This has an additional method `.repeat` (no args). This causes a repeat code to
 be transmitted. Should be called every 108ms if a button is held down.
 
 This has an additional method `.repeat` (no args). This causes a repeat code to
 be transmitted. Should be called every 108ms if a button is held down.
 


@@ -117,6 +131,11 @@ A value passed in `toggle` is ignored.
 
 #### Sony classes
 
 
 #### Sony classes
 

+Classes `SONY_12`, `SONY_15` and `SONY_20`. Example invocation:
+```python
+from ir_tx.sony import SONY_15
+```
+

 The SIRC protocol supports three sizes, supported by the following classes:
  1. 12 bit (7 data, 5 address) `SONY_12`
  2. 15 bit (7 data, 8 address) `SONY_15`
 The SIRC protocol supports three sizes, supported by the following classes:
  1. 12 bit (7 data, 5 address) `SONY_12`
  2. 15 bit (7 data, 8 address) `SONY_15`


@@ -128,6 +147,11 @@ value.
 
 #### Philips classes
 
 
 #### Philips classes
 

+Classes `RC5` and `RC6_M0`. Example invocation:
+```python
+from ir_tx.philips import RC5
+```
+

 The RC-5 protocol supports a 5 bit address and 6 or 7 bit (RC5X) data. The
 driver uses the appropriate mode depending on the `data` value provided.
 
 The RC-5 protocol supports a 5 bit address and 6 or 7 bit (RC5X) data. The
 driver uses the appropriate mode depending on the `data` value provided.
 


@@ -137,6 +161,42 @@ Both send a `toggle` bit which remains constant if a button is held down, but
 changes when the button is released. The application should implement this
 behaviour, setting the `toggle` arg of `.transmit` to 0 or 1 as required.
 
 changes when the button is released. The application should implement this
 behaviour, setting the `toggle` arg of `.transmit` to 0 or 1 as required.
 

+#### Microsoft MCE class
+
+Class `MCE`. Example invocation:
+```python
+from ir_tx.mce import MCE
+# MCE.init_cs = 3
+```
+There is a separate demo for the `MCE` class because of the need to send a
+message on key release. It is run by issuing:
+```python
+from ir_tx.mcetest import test
+```
+Instructions will be displayed at the REPL.
+
+I have been unable to locate a definitive specification: the protocol was
+analysed by a mixture of googling and experiment. Behaviour may change if I
+acquire new information. The protocol is known as OrtekMCE and the remote
+control is sold on eBay as VRC-1100.
+
+The remote was designed for Microsoft Media Center and is used to control Kodi
+on boxes such as the Raspberry Pi. With a suitable PC driver it can emulate a
+PC keyboard and mouse. The mouse emulation uses a different protocol: the class
+does not currently support it. Pressing mouse buttons and pad will cause the
+error function (if provided) to be called.
+
+This supports a 4 bit address, 6 bit data and 2 bit toggle. The latter should
+have a value of 0 for the first message, 1 for repeat messages, and 2 for a
+final message sent on button release.
+
+The remaining four bits are a checksum which the driver creates. The algorithm
+requires an initial 'seed' value which my testing proved to be 4. However the
+only [documentation](http://www.hifi-remote.com/johnsfine/DecodeIR.html#OrtekMCE)
+I could find stated that the value should be 3. I implemented this as a class
+variable `MCE.init_cs=4`. This enables it to be changed if some receivers
+require 3.
+

 # 4. Principle of operation
 
 ## 4.1 Pyboard
 # 4. Principle of operation
 
 ## 4.1 Pyboard


@@ -159,8 +219,7 @@ This is performed by two hardware timers initiated in the constructor. Timer 2,
 channel 1 is used to configure the output pin as a PWM channel. Its frequency
 is set in the constructor. The OOK is performed by dynamically changing the
 duty ratio using the timer channel's `pulse_width_percent` method: this varies
 channel 1 is used to configure the output pin as a PWM channel. Its frequency
 is set in the constructor. The OOK is performed by dynamically changing the
 duty ratio using the timer channel's `pulse_width_percent` method: this varies

-the pulse width from 0 to a duty ratio passed to the constructor. The NEC
-protocol defaults to 50%, the Sony and Philips ones to 30%.
+the pulse width from 0 to a duty ratio passed to the constructor.

 
 The duty ratio is changed by the Timer 5 callback `._cb`. This retrieves the
 next duration from the array. If it is not `STOP` it toggles the duty cycle
 
 The duty ratio is changed by the Timer 5 callback `._cb`. This retrieves the
 next duration from the array. If it is not `STOP` it toggles the duty cycle


@@ -176,18 +235,7 @@ The carrier is generated by PWM instance `.pwm` running continuously. The ABC
 constructor converts the 0-100 duty ratio specified by the subclass to the
 0-1023 range used by ESP32.
 
 constructor converts the 0-100 duty ratio specified by the subclass to the
 0-1023 range used by ESP32.
 

-# 5. References
-
-[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)
-
-Philips protocols:  
-[RC5](https://en.wikipedia.org/wiki/RC-5)  
-[RC5](https://www.sbprojects.net/knowledge/ir/rc5.php)  
-[RC6](https://www.sbprojects.net/knowledge/ir/rc6.php)
+## 4.3 Duty ratio

 
 

-Sony protocol:  
-[SIRC](https://www.sbprojects.net/knowledge/ir/sirc.php)
+In every case where I could find a specified figure it was 30%. I measured
+that from a variety of remotes, and in every case it was close to that figure.