Support transmit and receive on Samsung remotes.

[micorpython_ir.git] / TRANSMITTER.md

diff --git a/TRANSMITTER.md b/TRANSMITTER.md
index 4f15c656e190e56494ff0a6f3f76593f7a3bf445..c76995bb5390014de2e4b4dcbd55519aa818ab0c 100644 (file)
--- a/TRANSMITTER.md
+++ b/TRANSMITTER.md
@@ -13,10 +13,19 @@ On the Pyboard the transmitter test script assumes pin X1 for IR output. It can
 be changed, but it must support Timer 2 channel 1. Pins for pushbutton inputs
 are arbitrary: X3 and X4 are used. The driver uses timers 2 and 5.
 
 be changed, but it must support Timer 2 channel 1. Pins for pushbutton inputs
 are arbitrary: X3 and X4 are used. The driver uses timers 2 and 5.
 

-On ESP32 the demo uses pins 21 and 23 for IR output and pins 18 and 19 for
-pushbuttons. These pins may be changed.
+On ESP32 the demo uses pin 23 for IR output and pins 18 and 19 for pushbuttons.
+These pins may be changed. The only device resource used is `RMT(0)`.

 
 

-## 1.1 Pyboard Wiring
+On Raspberry Pi Pico the demo uses pin 17 for IR output and pins 18 and 19 for
+pushbuttons. These pins may be changed. The driver uses the PIO to emulate a
+device similar to the ESP32 RMT. The device driver is
+[documented here](./RP2_RMT.md); this is for experimenters and those wanting to
+use the library in conjunction with their own PIO assembler code.
+
+## 1.1 Wiring
+
+All microcontrollers require an external circuit to drive the LED. The notes
+below on specific microcontrollers assume that such a circuit is used.

 
 I use the following circuit which delivers just under 40mA to the diode. R2 may
 be reduced for higher current.  
 
 I use the following circuit which delivers just under 40mA to the diode. R2 may
 be reduced for higher current.  


@@ -30,20 +39,22 @@ increase power.
 The transistor type is not critical.
 
 The driver assumes circuits as shown. Here the carrier "off" state is 0V,
 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
-3.3V, the class variable `active_high` should be set `False`.
+which is the driver default. If using an alternative circuit where "off" is
+required to be 3.3V, the class variable `active_high` should be set `False`.

 
 ## 1.2 ESP32 Wiring
 
 
 ## 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 transistor type is not
-critical.  
-![Image](images/gate.png)
+The ESP32 RMT device now supports the carrier option, and this driver has been
+updated to use it. The same circuits as above may be used to connect to pin 23
+(or other pin, if the code has been adapted). The `active_high` option is not
+available on the ESP32 `RMT` object, so any alternative circuit must illuminate
+the LED if the pin state is high.
+
+## 1.3 RP2 Wiring

 
 

-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)
+There is no `active_high` option so the circuit  must illuminate the LED if the
+pin state is high, as per the above drivers. Test programs use pin 17, but this
+can be reassigned.

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


@@ -51,11 +62,17 @@ chosen type has a low gate-source threshold voltage and low Rdson.
 
 The device driver has no dependencies.
 
 
 The device driver has no dependencies.
 

-On ESP32 a firmware version >= V1.12 is required. The Loboris port is not
-supported owing to the need for the RMT device.
+On ESP32 a firmware version >= V1.17 is required. The Loboris port is not
+supported owing to the need for the RMT device and other issues.

 
 

-The demo program requires `uasyncio` from the official library and `aswitch.py`
-from [this repo](https://github.com/peterhinch/micropython-async).
+The demo program uses `uasyncio` primitives from
+[this repo](https://github.com/peterhinch/micropython-async). Clone the repo to
+a directory on your PC:
+```bash
+$ git clone https://github.com/peterhinch/micropython-async
+```
+move to its `v3` directory, and copy the `primitives` directory with its
+contents to the filesystem.

 
 ## 2.2 Installation
 
 
 ## 2.2 Installation
 


@@ -78,13 +95,36 @@ Instructions will be displayed at the REPL.
 
 # 3. The driver
 
 
 # 3. The driver
 

-This is specific to Pyboard D, Pyboard 1.x (not Lite) and ESP32.
+This is specific to Pyboard D, Pyboard 1.x (not Lite), ESP32 and Raspberry Pi
+Pico (RP2 architecture chip).

 
 It implements a class for each supported protocol, namely `NEC`, `SONY_12`,
 `SONY_15`, `SONY_20`, `RC5` and `RC6_M0`.  Each class is subclassed from a
 common abstract base class in `__init__.py`. The application instantiates the
 appropriate class and calls the `transmit` method to send data.
 
 
 It implements a class for each supported protocol, namely `NEC`, `SONY_12`,
 `SONY_15`, `SONY_20`, `RC5` and `RC6_M0`.  Each class is subclassed from a
 common abstract base class in `__init__.py`. The application instantiates the
 appropriate class and calls the `transmit` method to send data.
 

+Basic usage on a Pyboard:
+```python
+from machine import Pin
+from ir_tx.nec import NEC
+nec = NEC(Pin('X1'))
+nec.transmit(1, 2)  # address == 1, data == 2
+```
+Basic usage on ESP32:
+```python
+from machine import Pin
+from ir_tx.nec import NEC
+nec = NEC(Pin(23, Pin.OUT, value = 0))
+nec.transmit(1, 2)  # address == 1, data == 2
+```
+Basic usage on Pico:
+```python
+from machine import Pin
+from ir_tx.nec import NEC
+nec = NEC(Pin(17, Pin.OUT, value = 0))
+nec.transmit(1, 2)  # address == 1, data == 2
+```
+

 #### Common to all classes
 
 Constructor args:  
 #### Common to all classes
 
 Constructor args:  


@@ -97,21 +137,42 @@ Constructor args:
  3. `verbose=False` If `True` emits (a lot of) debug output.
 
 Method:
  3. `verbose=False` If `True` emits (a lot of) debug output.
 
 Method:

- 1. `transmit(addr, data, toggle=0)` Integer args. `addr` and `data` are
- normally 8-bit values and `toggle` is normally 0 or 1; details are protocol
- dependent and are described below.
+ 1. `transmit(addr, data, toggle=0, validate=False)` Args `addr`, `data` and
+ `toggle` are positive integers. The maximum vaues are protocol dependent. If
+ `validate` is `True` passed values are checked and a `ValueError` raised if
+ they are out of range. If `validate` is false invalid bits are silently
+ discarded. For example if an address of 0x11 is passed to `MCE.transmit`, the
+ address sent will be 1 because that protocol supports only a four bit address
+ field. The `toggle` field is unused by some protocols when 0 should be passed.
+
+Class method:
+ 1. `active_low` No args. Pyboard only. A `ValueError` will be thrown on ESP32.
+ The IR LED drive circuit is usually designed to turn the LED on if the driver
+ pin is high. If it has opposite polarity the method must be called before
+ instantiating the class - it will be ineffective if called later.
+
+Class varaible:
+ 1. `timeit=False` If `True` the `.transmit` method times itself and prints the
+ result in μs.

 
 The `transmit` method is synchronous with rapid return. Actual transmission
 
 The `transmit` method is synchronous with rapid return. Actual transmission

-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.
-
-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
+occurs as a background process, on the Pyboard controlled by timers 2 and 5. On
+ESP32 the RMT class is used. Execution times were measured on a Pyboard 1.1 and
+the ESP32 reference board  without SPIRAM. Tests were done at stock frequency and
+with `validate=True`, `verbose=False`. A small saving could be achieved by
+skipping validation.
+
+| Protocol | ESP32 | Pyboard |
+|:--------:|:-----:|:-------:|
+| NEC      | 7.8ms | 3.2ms   |
+| SONY12   | 3.2ms | 1.3ms   |
+| SONY15   | 3.6ms | 1.5ms   |
+| SONY20   | 4.5ms | 1.9ms   |
+| RC5      | 4.9ms | 1.5ms   |
+| RC6_M0   | 6.0ms | 2.0ms   |
+| MCE      | 6.7ms | 2.0ms   |
+
+#### NEC class (also Samsung)

 
 Class `NEC`. Example invocation:
 ```python
 
 Class `NEC`. Example invocation:
 ```python


@@ -129,6 +190,16 @@ the complement for values < 256.
 
 A value passed in `toggle` is ignored.
 
 
 A value passed in `toggle` is ignored.
 

+For Samsung protocol set the `samsung` class variable `True`:
+```python
+from ir_tx.nec import NEC
+NEC.samsung=True
+```
+Samsung remotes do not seem to use repeat codes: the sample I have simply
+repeats the original code.
+
+Thanks are due to J.E.Tannenbaum for information about the Samsung protocol.
+

 #### Sony classes
 
 Classes `SONY_12`, `SONY_15` and `SONY_20`. Example invocation:
 #### Sony classes
 
 Classes `SONY_12`, `SONY_15` and `SONY_20`. Example invocation:


@@ -199,8 +270,6 @@ require 3.
 
 # 4. Principle of operation
 
 
 # 4. Principle of operation
 

-## 4.1 Pyboard
-

 The classes inherit from the abstract base class `IR`. This has an array `.arr`
 to contain the duration (in μs) of each carrier on or off period. The
 `transmit` method calls a `tx` method of the subclass which populates this
 The classes inherit from the abstract base class `IR`. This has an array `.arr`
 to contain the duration (in μs) of each carrier on or off period. The
 `transmit` method calls a `tx` method of the subclass which populates this


@@ -212,30 +281,85 @@ this is required for bi-phase (manchester) codings.
 The `.add` method takes a single μs time value and adds it to the last value
 in the array: this pulse lengthening is used in bi-phase encodings.
 
 The `.add` method takes a single μs time value and adds it to the last value
 in the array: this pulse lengthening is used in bi-phase encodings.
 

-On completion of the subclass `.tx`, `.transmit` appends a special `STOP` value
-and initiates physical transmission which occurs in an interrupt context.
+On completion of the subclass `.tx`, `.transmit` calls `.trigger` which
+initiates transmission as a background process. Its behaviour is platform
+dependent.

 
 

-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
-the pulse width from 0 to a duty ratio passed to the constructor.
+## 4.1 Pyboard
+
+Tramsmission 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 the pulse width from 0 to the 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

-and re-initialises T5 for the new duration.
+and re-initialises T5 for the new duration. If it is `STOP` it ensures that the
+duty ratio is set to the `_SPACE`
+
+Here `.trigger` appends a special `STOP` value and initiates physical
+transmission by calling the Timer5 callback.

 
 ## 4.2 ESP32
 
 
 ## 4.2 ESP32
 

-The carrier is output continuously at the specified duty ratio. A pulse train
-generated by the RMT instance drives a hardware gate such that the IR LED is
-lit only when both carrier and RMT are high.
+The RMT class now supports `carrier_freq` and `carrier_duty_percent`
+constructor args, so the base class `IR` (in `__init__.py`) uses these to
+enable the OOK (on-off keying) waveform.

 
 

-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.
+The `.trigger` method calls `RMT.write_pulses` and returns with `RMT` operating
+in the background.

 
 ## 4.3 Duty ratio
 
 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.
 
 ## 4.3 Duty ratio
 
 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.

+
+# 5. Unsupported protocols
+
+You can use the receiver module to capture an IR burst and replay it with the
+transmitter. This enables limited support for unknown protocols. This is
+strictly for experimenters and I haven't documented it in detail.
+
+There are two limitations. The first is timing accuracy: both receiving and
+transmitting processes introduce some timing uncertainty. This is only likely
+to be a practical problem with fast protocols. In brief testing with a known
+protocol the scripts below worked.
+
+The more tricky problem is handling repeat keys: different protocols use widely
+varying approaches. If repeat keys are to be supported some experimentation and
+coding is likely to be required.
+
+The following captures a single burst and saves it to a file:  
+```python
+from ir_rx.acquire import test
+import ujson
+
+lst = test()  # May report unsupported or unknown protocol
+with open('burst.py', 'w') as f:
+    ujson.dump(lst, f)
+```
+This replays it:  
+```python
+from ir_tx import Player
+from sys import platform
+import ujson
+
+if platform == 'esp32':
+    from machine import Pin
+    pin = (Pin(23, Pin.OUT, value = 0), Pin(21, Pin.OUT, value = 0))
+else:
+    from pyb import Pin, LED
+    pin = Pin('X1')
+with open('burst.py', 'r') as f:
+    lst = ujson.load(f)
+ir = Player(pin)
+ir.play(lst)
+```
+The `ir_tx.Player` class is a minimal subclass supporting only the `.play`
+method. This takes as an arg an iterable comprising time values of successive
+mark and space periods (in μs).
+
+The `ir_rx.acquire.test` function makes assumptions about the likely maximum
+length and maximum duration of a burst. In some cases this may require some
+modification e.g. to instantiate `IR_GET` with different args.