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updated documentation to match latest version of code

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Youen Toupin 4 years ago
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  1. 2
      README.md
  2. 42
      documentation.md
  3. 2
      examples/FakeDS18B20/README.md
  4. 83
      extras/documentation.md
  5. 1
      src/OneWireSlave.h

2
README.md

@ -5,4 +5,4 @@ An arduino library to communicate using the Dallas one-wire protocol, where the
1-wire allows communication over long distances (100m and more, see Dallas documentation for details) with a single wire (plus a ground wire). You can put as much devices as you want on the same wire (they communicate one at a time). 1-wire also allows to send power over the data wire (parasitic power), but, though I haven't tried, I don't believe it would work with an Arduino. You'll need a separate 5V power source, which, if it comes next to your data wire, means you need 3 wires (5V, data, and ground). You'll also need a master controller, for example the USB adapter DS9490R, to connect to a computer, that will control communication with all 1-wire devices.
## How to use this library
Take a look at [the documentation of the library](./documentation.md)
Take a look at [the documentation of the library](extras/documentation.md)

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documentation.md

@ -1,42 +0,0 @@
This library allows you to emulate existing 1-wire devices with an Arduino, or to create your own protocol. All low-level details are handled by the library, such as reset detection, ROM matching, byte sending and receiving. Look at the demo sketch to see an example.
# Compatible boards
If you have tested the library on another board, please send a pull-request (or just tell me which board) to update this list.
## ATmega328
- Arduino Uno (tested by [neuoy](https://github.com/neuoy))
# Getting started
See example "FakeDS18B20", and the associated [documentation](examples/FakeDS18B20/README.md), for a working use case of the library.
# Reference
## setReceiveCallback
`void setReceiveCallback(void(*callback)(ReceiveEvent evt, byte data))`
Sets the function that will be called back when an event occurs, such as when a byte is received.
## begin
`void begin(byte* rom, byte pinNumber)`
Starts the library, which will respond to the provided ROM (must be unique on your network) on the specified Arduino pin. The ROM is cloned by the library, so you can discard your buffer immediately if you want.
## write
`void write(byte* bytes, short numBytes, void(*complete)(bool error))`
Starts writing one or more bytes, and will call the provided callback (optional) when it's done. The buffer you provide here must stay available until the end of the write operation, which happens in background. Do not use local variables.
# Notes about the interrupt-based implementation
Since the library is implemented using interrupts, none of its functions will block: you can continue execute your code immediately.
This also means callbacks are called from interrupt handlers, so you must make them very short to not block further communication.
You must also be careful when you explicitely block interrupts, as the 1-wire protocol has very tight timings, especially when writing bytes (which also happens when searching for device ROMs): a delay of 3 microseconds (yes, microseconds, not milliseconds) can be enough for some (quite intolerant) masters to miss a bit.
But if your code only blocks interrupts for reasonably short time, the probability to block exactly at the bad moment is low, so you can easily mitigate the issue by adding CRC checks in your high-level communication protocol, and retrying when an error is detected. This is an important thing to do anyway because 1-wire does not natively perform any error checking (excepted for ROM operations which already contain a CRC byte). Standard 1-wire devices also include CRC checks in their specific protocols.

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examples/FakeDS18B20/README.md

@ -13,4 +13,4 @@ You will see 28.000000000002 probe that always return 42 as temperature :
42
Conversion timing is emulated as well.
If you don't use an Arduino Uno, you may need to adjust which pin you connect as the data line (it needs to have hardware interrupts), and make the corresponding change in the example source code. A few microcontrollers are compatible with the library, check the full list in [the documentation](../../documentation.md).
If you don't use an Arduino Uno, you may need to adjust which pin you connect as the data line (it needs to have hardware interrupts), and make the corresponding change in the example source code. A few microcontrollers are compatible with the library, check the full list in [the documentation](../../extras/documentation.md).

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extras/documentation.md

@ -0,0 +1,83 @@
# OneWireSlave library documentation
This library allows you to emulate existing 1-wire devices with an Arduino, or to create your own protocol. All low-level details are handled by the library, such as reset detection, ROM matching, byte sending and receiving. Look at the demo sketch to see an example.
## Compatible boards
If you have tested the library on another board, please send a pull-request (or just tell me which board) to update this list.
### ATmega328
- Arduino Uno (tested by [neuoy](https://github.com/neuoy))
## Getting started
See example "FakeDS18B20", and the associated [documentation](examples/FakeDS18B20/README.md), for a working use case of the library.
## Library reference
### setReceiveCallback
`void setReceiveCallback(void(*callback)(ReceiveEvent evt, byte data))`
Sets the function that will be called back when an event occurs, such as when a byte is received.
### begin
`void begin(byte* rom, byte pinNumber)`
Starts the library, which will respond to the provided ROM (must be unique on your network) on the specified Arduino pin. The ROM is cloned by the library, so you can discard your buffer immediately if you want.
### write
`bool write(const byte* bytes, short numBytes)`
Writes the specified bytes synchronously. This function blocks until the write operation has finished. Do not call from an interrupt handler! Returns true in case of success, false if an error occurs.
### beginWrite
`void beginWrite(const byte* bytes, short numBytes, void(*complete)(bool error))`
Starts sending the specified bytes. They will be sent in the background, and the buffer must remain valid and unchanged until the write operation has finished or is cancelled. The optional callback is used to notify when the bytes are sent, or if an error occured. Callbacks are executed from interrupts and should be as short as possible. If `bytes` is null or `numBytes` is 0, nothing is sent, which is equivalent to calling `stopWrite`. In any case, calling the write function will cancel the previous write operation if it didn't complete yet.
### setReceiveBitCallback
`void setReceiveBitCallback(void(*callback)(bool bit))`
Sets (or replaces) a function to be called when a bit is received. The byte reception callback is called after that if the received bit was the last of a byte. The callback is executed from interrupts and should be as short as possible. Failure to return quickly can prevent the library from correctly reading the next bit.
### writeBit
`bool writeBit(bool value)`
Writes a single bit synchronously. This function blocks until the bit is sent. Do not call from an interrupt handler! Returns true in case of success, false if an error occurs.
### beginWriteBit
`void beginWriteBit(bool value, bool repeat = false, void(*bitSent)(bool error) = 0)`
Sets a bit that will be sent next time the master asks for one. Optionnaly, the repeat parameter can be set to true to continue sending the same bit each time. In both cases, the send operation can be canceled by calling `stopWrite`.
### stopWrite
`void stopWrite()`
Cancels any pending write operation, started by writeBit or write. If this function is called before the master asked for a bit, then nothing is sent to the master.
### alarmed
`void alarmed(bool value)`
Sets the alarmed state, that is used when the master makes a conditional search of alarmed devices.
### setLogCallback(void(*callback)(const char* message))
`void setLogCallback(void(*callback)(const char* message))`
Sets (or replaces) a function to be called when the library has a message to log, if the functionality is enabled in OneWireSlave.cpp (uncomment line `#define ERROR_MESSAGES`). This is for debugging purposes.
### end
`void end()`
Stops all 1-wire activities, which frees hardware resources for other purposes.
## Notes about the interrupt-based implementation
Since the library is implemented using interrupts, none of its functions will block: you can continue execute your code immediately.
This also means callbacks are called from interrupt handlers, so you must make them very short to not block further communication.
You must also be careful when you explicitely block interrupts, as the 1-wire protocol has very tight timings, especially when writing bytes (which also happens when searching for device ROMs): a delay of 3 microseconds (yes, microseconds, not milliseconds) can be enough for some (quite intolerant) masters to miss a bit.
But if your code only blocks interrupts for reasonably short time, the probability to block exactly at the bad moment is low, so you can easily mitigate the issue by adding CRC checks in your high-level communication protocol, and retrying when an error is detected. This is an important thing to do anyway because 1-wire does not natively perform any error checking (excepted for ROM operations which already contain a CRC byte). Standard 1-wire devices also include CRC checks in their specific protocols.

1
src/OneWireSlave.h

@ -44,6 +44,7 @@ public:
//! Cancels any pending write operation, started by writeBit or write. If this function is called before the master asked for a bit, then nothing is sent to the master.
void stopWrite();
//! Sets the alarmed state, that is used when the master makes a conditional search of alarmed devices.
void alarmed(bool value);
static byte crc8(const byte* data, short numBytes);

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