In my testing a 38KHz demodulator worked with 36KHz and 40KHz remotes, but this
is obviously neither guaranteed nor optimal.
+The TSOP4838 can run from 3.3V or 5V supplies. The former should be used on
+non-5V compliant hosts such as ESP32 and Raspberry Pi Pico and is fine on 5V
+compliant hosts too.
+
The pin used to connect the decoder chip to the target is arbitrary. The test
-program assumes pin X3 on the Pyboard, pin 23 on ESP32 and pin 13 on ESP8266.
-On the WeMos D1 Mini the equivalent pin is D7.
+program `acquire.py` uses the following pins by default:
+
+| Host | Pin | Notes |
+|:-------:|:---:|:-----:|
+| Pyboard | X3 | |
+| ESP32 | 23 | |
+| ESP8266 | 13 | |
+| D1 Mini | D7 | WeMos name for pin 13. |
+| Pico | 16 | |
A remote using the NEC protocol is [this one](https://www.adafruit.com/products/389).
-# 2. Installation and demo script
+# 2. Installation and demo scripts
The receiver is a Python package. This minimises RAM usage: applications only
-import the device driver for the protocol in use.
-
+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_rx` Directory and contents.
There are no dependencies.
-The demo can be used to characterise IR remotes. It displays the codes returned
-by each button. This can aid in the design of receiver applications. The demo
-prints "running" every 5 seconds and reports any data received from the remote.
+## 2.1 Test scripts
+The demo can be used to characterise IR remotes where the protocol is known. It
+displays the codes returned by each button. This can aid in the design of
+receiver applications. The demo prints "running" every 5 seconds and reports
+any data received from the remote.
```python
from ir_rx.test import test
```
Instructions will be displayed at the REPL.
+If the protocol in use is unknown, there are two options: trial and error with
+the above script or run the following:
+```python
+from ir_rx.acquire import test
+test()
+```
+This script waits for a single burst from the remote and prints the timing of
+the pulses followed by its best guess at the protocol. It correctly identifies
+supported protocols, but can wrongly identify unsupported protocols. The
+report produced by the script exposed to an unknown protocol is unpredictable.
+The `test()` function returns a list of the mark and space periods (in μs).
+
# 3. The driver
This implements a class for each supported protocol. Each class is subclassed
Bound variable:
1. `verbose=False` If `True` emits debug output.
-Method:
- 1. `error_function` Arg: a function taking a single `int` arg. If this is
- specified it will be called if an error occurs. The value corresponds to the
- error code (see below). Typical usage might be to provide some user feedback
- of incorrect reception although beware of occasional triggers by external
- events. In my testing the TSOP4838 produces 200µs pulses on occasion for no
- obvious reason. See [section 4](./RECEIVER.md#4-errors).
+Methods:
+ 1. `error_function` Arg: a function taking a single `int` arg. If specified
+ the function will be called if an error occurs. The arg value corresponds to
+ the error code. Typical usage might be to provide some user feedback of
+ incorrect reception although beware of occasional triggers by external events.
+ In my testing the TSOP4838 produces 200µs pulses on occasion for no obvious
+ reason. See [section 4](./RECEIVER.md#4-errors).
+ 2. `close` No args. Shuts down the pin and timer interrupts.
A function is provided to print errors in human readable form. This may be
invoked as follows:
1. These are constants defining the NEC repeat code and the error codes sent
to the error function. They are discussed in [section 4](./RECEIVER.md#4-errors).
-#### NEC classes
+#### NEC classes (includes Samsung)
-`NEC_8`, `NEC_16`
+`NEC_8`, `NEC_16`, `SAMSUNG`
Typical invocation:
```python
address: the complement is checked and the address returned as an 8-bit value.
A 16-bit address will result in an error.
+The `SAMSUNG` class returns 16 bit address and data values. The remote sample
+tested did not issue repeat codes - if a button is held down it simply repeated
+the original value. In common with other NEC classes the callback receives a
+value of 0 in the `ctrl` arg.
+
+Thanks are due to J.E.Tannenbaum for information about the Samsung protocol.
+
#### Sony classes
`SONY_12`, `SONY_15`, `SONY_20`
from ir_rx.philips import RC5_IR
```
-These support the RC-5 and RC-6 mode 0 protocols respectively.
+These support the RC-5 (including RC-5X) and RC-6 mode 0 protocols
+respectively.
+
+#### Microsoft MCE class
+
+`MCE`
+
+Typical invocation:
+```python
+from ir_rx.mce import MCE
+```
+
+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.
+
+Args passed to the callback comprise 4 bit `addr`, 6 bit `data` and 2 bit `ctrl`
+with the latter having the value 0 for the first message and 2 for the message
+sent on key release. Intermediate messages (where the key is held down) have
+value 1.
+
+There is a 4-bit checksum which is used by default. 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 remotes use 3.
+If the value is set to -1 the check will be skipped.
# 4. Errors
a Pyboard D SF2W at stock frequency. They were: NEC 1ms for normal data, 100μs
for a repeat code. Philips codes: RC-5 900μs, RC-6 mode 0 5.5ms.
-# 7. 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)
+# 7. Unsupported protocols
-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)
-
-Sony protocol:
-[SIRC](https://www.sbprojects.net/knowledge/ir/sirc.php)
+It is possible to capture an IR burst from a remote and to re-create it using
+the transmitter. This has limitations and is discussed in detail in
+[the transmitter doc](./TRANSMITTER.md#5-unsupported-protocols).
# Appendix 1 NEC Protocol description
burst is constant, giving a constant burst length of 67.5ms. In extended
address mode this constancy is lost. The burst length can (by my calculations)
run to 76.5ms.
+
+# Appendix 2 MCE Protocol
+
+The bitstream comprises a header (2ms mark, 1ms space) followed by 16 bits of
+Manchester encoded data with a bit time of 500μs. Data are encoded
+```
+ccccddddddppaaaa
+```
+Where `aaaa` is the address, `pp` is the position (toggle) field, `dddddd` is
+data and `cccc` is a checksum. This is calculated by counting the ones in
+`ddddddppaaaa` and adding 4. Data are transmitted LSB first.
+
+The only [doc](http://www.hifi-remote.com/johnsfine/DecodeIR.html#OrtekMCE) I
+could find states that the checksum seed value is 3, but this did not match the
+remote I have.
projects / micorpython_ir.git / blobdiff