uart - serial port operation library

Adapted Air780E Air780EP Air780EPS Air780EQ Air700EAQ Air700EMQ Air700ECQ Air201

Note

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Tip

This library has its own demo,click this link to view the demo example of uart

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There are also video tutorials in this library, click this link to view

Constant

constant	type	explanation
uart.Odd	number	odd check, case compatibility
uart.Even	number	Even parity, case compatibility
uart.None	number	No checksum, case compatibility
uart.ODD	number	odd check
uart.EVEN	number	even check
uart.NONE	number	No verification
uart.LSB	number	Little Endian Mode
uart.MSB	number	Big Endian Mode
uart.VUART_0	number	Virtual Serial Port 0
uart.ERROR_DROP	number	Discard cached data when error is encountered
uart.DEBUG	number	Enable debugging function

uart.setup(id, baud_rate, data_bits, stop_bits, partiy, bit_order, buff_size, rs485_gpio, rs485_level, rs485_delay, debug_enable, error_drop)

Configure Serial Port Parameters

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1, and so on, the maximum value depends on the device
int	Baud rate, default 115200, optional baud rate table:{2000000,921600,460800,230400,115200,57600,38400,19200,9600,4800,2400}
int	Data bit, default is 8, optional 7/8
int	Stop bit, default is 1, according to the actual situation, there can be 0.5/1/1.5/2, etc.
int	check digit, optional uart.None/uart.Even/uart.Odd
int	Size end, default small end uart.LSB, optional uart.MSB
int	buffer size, default 1024
int	485 Conversion GPIO in mode, default 0xffffffff
int	485 The level of GPIO in the rx direction in the mode, the default value.0
int	485 The delay time of tx to rx conversion in the mode, the default value is 12bit time, the unit is us, and the baud rate is 9600.20000
int	Turn on the debugging function, enable by default, fill in uart.DEBUG or non-digital enable, other values are turned off, currently only supported by the core shift platform
int	Whether to abandon cached data in case of receiving error, enable by default, fill in uart.ERROR_DROP or non-digital enable, other values are closed, currently only supported by the core transfer platform

Return Value

return value type	explanation
int	Returns 0 on success, other values on failure

Examples

-- Most commonly used 115200 8N1
uart.setup(1, 115200, 8, 1, uart.NONE)
-- can be abbreviated uart.setup(1)

-- 485 Automatic switching, select GPIO10 as the transceiver conversion pin
uart.setup(1, 115200, 8, 1, uart.NONE, uart.LSB, 1024, 10, 0, 2000)
-- Receive error not discarded cached data
uart.setup(1, 115200, 8, 1, uart.NONE, nil, 1024, nil, nil, nil, nil, 0)

---

uart.write(id, data)

Write serial port

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1
string/zbuff	The data to be written, if it is zbuff, it will be read from the starting position of the pointer.
int	Optional. The length of the data to be sent. The default value is full.

Return Value

return value type	explanation
int	Success Data Length

Examples

-- Write visible string
uart.write(1, "rdy\r\n")
-- Write a data string in hexadecimal
uart.write(1, string.char(0x55,0xAA,0x4B,0x03,0x86))

---

uart.read(id, len)

Read Serial Port

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1
int	Read Length
file/zbuff	optional: File handle or zbuff object

Return Value

return value type	explanation
string	When reading data/passing in zbuff, return the length of the read and move the zbuff pointer back.

Examples

uart.read(1, 16)

---

uart.close(id)

Close Serial Port

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1

Return Value

return value type	explanation
nil	No return value

Examples

uart.close(1)

---

uart.on(id, event, func)

Register Serial Port Event Callback

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1
string	Event Name
function	Callback Method

Return Value

return value type	explanation
nil	No return value

Examples

uart.on(1, "receive", function(id, len)
    local data = uart.read(id, len)
    log.info("uart", id, len, data)
end)

---

uart.wait485(id)

Waiting for TX to complete in 485 mode is only required when mcu does not support serial port sending shift register empty or similar interrupt, and is used after send event callback

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1

Return Value

return value type	explanation
int	How many cycles have I waited for tx to complete, which is used to observe whether the delay time is sufficient for rough observation. If the return is not 0, it means that it needs to be enlarged.delay

Examples

None

---

uart.exist(id)

Check whether the serial port number exists

Parameters

Incoming Value Type	Explanation
int	The serial port id, uart0 writes 0, uart1 writes 1, and so on.

Return Value

return value type	explanation
bool	Existence return true

Examples

None

---

uart.rx(id, buff)

buff Form read serial port, read all data at one time and store it in buff. If there is not enough buff space, it will automatically expand. Currently, air105 air780e supports this operation.

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1
zbuff	zbuff Object

Return Value

return value type	explanation
int	Returns the length of the read and moves the zbuff pointer backward

Examples

uart.rx(1, buff)

---

uart.rxSize(id)

Read the remaining amount of data in the serial port Rx buffer. Currently, air105 air780e supports this operation.

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1

Return Value

return value type	explanation
int	Returns the length of the read

Examples

local size = uart.rxSize(1)

---

uart.rxClear(id)

Clear the remaining amount of data in the serial port Rx buffer. Currently, air105 air780e supports this operation.

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1

Return Value

None

Examples

uart.rxClear(1)

---

uart.tx(id, buff, start, len)

buff Form to write serial port, equivalent to c language uart_tx(uart_id, &buff[start], len);

Parameters

Incoming Value Type	Explanation
int	Serial ID, uart0 writes 0, uart1 writes 1
zbuff	The data to be written, if it is zbuff, it will be read from the starting position of the pointer.
int	Optional. The starting position of the data to be sent. The default value is 0
int	Optional. The length of the data to be sent is valid data in zbuff by default. The maximum value does not exceed the maximum space in zbuff.

Return Value

return value type	explanation
int	Success Data Length

Examples

uart.tx(1, buf)

---

uart.createSoft(tx_pin, tx_hwtimer_id, rx_pin, rx_hwtimer_id, adjust_period)

Set the hardware configuration of the software uart. Only SOC that supports hardware timers can be used. Currently, only one can be set. The baud rate has different limits according to the software and hardware configuration of the platform. It is recommended to 9600, the receiving cache does not exceed 65535, and MSB is not supported. Support 485 automatic control. The subsequent setup operation is still required.

Parameters

Incoming Value Type	Explanation
int	Send Pin Number
int	Hardware timer for sending ID
int	Receive pin number
int	Hardware timer for reception ID
int	Send timing adjustment, the unit is the timer clock cycle, the default is 0, need to be fine-tuned according to the oscilloscope or logic analyzer
int	Receive timing adjustment, the unit is the timer clock cycle, the default is 0, need to be fine-tuned according to the oscilloscope or logic analyzer

Return Value

return value type	explanation
int	the id of the software uart. if it fails, it returns nil

Examples

-- Initialize software uart
local uart_id = uart.createSoft(21, 0, 1, 2) --air780e It is recommended to use timers 0 and 2. tx_pin is preferably AGPIO to prevent the opposite end from being triggered by mistake during sleep.RX

---

uart.list(max)

Get a list of available serial numbers, currently only win32

Parameters

Incoming Value Type	Explanation
int	Optional, the default 256, the maximum number of serial ports to obtain

Return Value

return value type	explanation
table	List of available serial port numbers obtained

Examples

None

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