79 lines
3.1 KiB
Markdown
79 lines
3.1 KiB
Markdown
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# SoftUART Module
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| Since | Origin / Contributor | Maintainer | Source |
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| :----- | :-------------------- | :---------- | :------ |
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|2019-12-27 | [pleningerweb](https://github.com/plieningerweb/), [juancgalvez](https://github.com/juancgalvez/), [crasu](https://github.com/crasu/), [galjonsfigur](https://github.com/galjonsfigur/)| [galjonsfigur](https://github.com/galjonsfigur/) | [softuart.c](../../app/modules/softuart.c) |
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The SoftUART module provides access to multiple software-based UART ports.
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ESP8266 has only 1 full hardware UART port that is used to program the chip and communicate with NodeMCU firmware. The second port is transmit-only. More information can be found in [uart module documentation](uart/). This module provides access to more UART ports and can be used to communicate with devices like GSM or GPS modules. The code is based on [esp8266-software-uart](https://github.com/plieningerweb/esp8266-software-uart) and [Arduino-esp8266-Software-UART](https://github.com/juancgalvez/Arduino-esp8266-Software-UART) projects. Currently doesn't support inverted serial data logic or modes other than 8N1. It's important to notice that this is a software implementation of the serial protocol. There could be some interrupts that make the transmition or reception fail due to invalid timing.
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!!! note
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SoftUART cannot be used on D0 pin.
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## softuart.setup()
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Creates new SoftUART instance. Note that rx pin cannot be shared between instances but tx pin can.
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#### Syntax
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`softuart.setup(baudrate, txPin, rxPin)`
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#### Parameters
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- `baudrate`: SoftUART baudrate. Maximum supported is 230400.
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- `txPin`: SoftUART tx pin. If set to `nil` `write` method will not be supported.
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- `rxPin`: SoftUART rx pin. If set to `nil` `on("data")` method will not be supported.
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#### Returns
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`softuart` instance.
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#### Example
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```lua
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-- Create new software UART with baudrate of 9600, D2 as Tx pin and D3 as Rx pin
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s = softuart.setup(9600, 2, 3)
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```
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# SoftUART port
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## softuart.port:on()
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Sets up the callback function to receive data.
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#### Syntax
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`softuart.port:on(event, trigger, function(data))`
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#### Parameters
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- `event`: Event name. Currently only `data` is supported.
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- `trigger`: Can be a character or a number. If character is set, the callback function will only be run when that character gets received. When a number is set, the callback function will only be run when buffer will have as many characters as number.
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- `function(data)`: Callback function. the `data` parameter is software UART receiving buffer.
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#### Returns
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`nil`
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#### Example
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```lua
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-- Create new software UART with baudrate of 9600, D2 as Tx pin and D3 as Rx pin
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s = softuart.setup(9600, 2, 3)
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s:on("data", 10, function(data)
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print("Lua handler called!")
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print(data)
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end)
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```
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## softuart.port:write()
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Transmits a byte or sequence of them.
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#### Syntax
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`softuart.port:write(data)`
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#### Parameters
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- `data`: Can be a number or string. When a number is passed, only one byte will be sent. When a string is passed, whole sequence will be transmitted.
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#### Returns
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`nil`
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#### Example
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```lua
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-- Create new software UART with baudrate of 9600, D2 as Tx pin and D3 as Rx pin
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s = softuart.setup(9600, 2, 3)
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s:write("Hello!")
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```
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