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157 lines
4.8 KiB
Markdown
157 lines
4.8 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/SWSerialOut/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/SWSerialOut/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/SWSerialOut/issues)
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[](https://github.com/RobTillaart/SWSerialOut/blob/master/LICENSE)
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[](https://github.com/RobTillaart/SWSerialOut/releases)
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[](https://registry.platformio.org/libraries/robtillaart/SWSerialOut)
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# SWSerialOut
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Arduino library for SWSerialOut, supports only data out (TX).
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## Description
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**Experimental**
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SWSerialOut is a library that only implements the transmit function.
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There are devices that do not send back information, or in some cases
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you do not use the "returned" information.
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In those cases there is no need for the receive function, interrupt
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handling, buffers etc.
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This is where SWSerialOut comes in, it can only transmit data and does
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that by implementing the **public Stream** interface.
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So its interface is similar to any Stream like Serial or SoftwareSerial,
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as the user can use **print()** and **println()** for al the output.
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The input side of the Stream interface, **available()**, **peek()**,
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and **read()** are stubs returning 0.
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The library does not need to buffer incoming data, and it does not buffer outgoing data either. Therefore it can be blocking.
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So use the library with care.
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#### Test
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Test are done with example sketch **SWSO_test.ino** et al which
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reads the send data back via hardware Serial.
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The serial pulses, especially baud rates above 19200, will improve
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with a proper pull up resistor e.g. 4K7.
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| baud | UNO | ESP32 | other |
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|---------:|:-----:|:-------:|:-------:|
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| 300 | Y | Y |
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| 600 | Y | Y |
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| 1200 | Y | Y |
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| 2400 | Y | Y |
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| 4800 | Y | Y |
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| 7200 | Y | Y |
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| 9600 | Y | Y |
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| 19200 | Y | Y |
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| 38400 | - | Y |
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| 57600 | - | Y |
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| 76800 | - | Y |
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| 100000 | - | Y |
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Note: the code is not really optimized for any platform (yet).
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So the library will not match the top speed of other software serial implementations.
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If you have tested this library with another platform, please let me know by
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opening an issue with the relevant data.
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#### Related
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- https://github.com/RobTillaart/MiniMP3 - minimal version only needs serial out.
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## Interface
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```cpp
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#include "SWSerialOut.h"
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```
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#### Constructor
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- **SWSerialOut(uint8_t TXpin)** constructor.
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- **void begin(uint32_t baudRate)** set baud rate (see table above)
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- **void begin(uint32_t baudRate, char \* params)** params implemented.
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however not tested yet.
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The params are range checked.
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params is e.g. "8N1" = 8 bit, None parity, 1 stop-bit
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| param | value | default | notes |
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|:---------:|:----------|:---------:|:--------|
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| bit | 5,6,7,8 | 8 | to be tested
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| parity | N,E,O,S,M | N | to be tested
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| stop bits | 0,1,2,3 | 1 | to be tested
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#### Stream interface
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The SWSerialOut implements the **public Stream** interface, so
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it will support the following functions (indirect from Print):
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- **size_t write(char c)** idem.
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- **size_t print(...)** idem.
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- **size_t println(...)** idem.
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The input functions are stubs, just returning 0.
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#### Interrupts
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To have a more constant timing while sending the bits one can disable
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interrupts during the transfer of the data.
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- **void disableInterrupts(bool b)** enable/disable interrupts during send.
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#### Debug
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- **void debug()** dump internal variables.
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## Future
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#### Must
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- update documentation
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- test bits, parity, stop bits
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#### Should
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- examples
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- performance sketch
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#### Could
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- unit tests?
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- support inverse logic.
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- support 9 bits (low priority)
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- add RTS / CTS handshake?
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- investigate optimized transfer per platform
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- higher baud rates, especially AVR.
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#### Wont
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- read()
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- non blocking version
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## Support
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If you appreciate my libraries, you can support the development and maintenance.
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Improve the quality of the libraries by providing issues and Pull Requests, or
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donate through PayPal or GitHub sponsors.
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Thank you,
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