UART Module¶
Since | Origin / Contributor | Maintainer | Source |
---|---|---|---|
2014-12-22 | Zeroday | Zeroday | uart.c |
The UART (Universal asynchronous receiver/transmitter) module allows configuration of and communication over the UART serial port.
The default setup for the uart is controlled by build-time settings. The default rate is 115,200 bps. In addition, auto-baudrate detection is enabled for the first two minutes
after platform boot. This will cause a switch to the correct baud rate once a few characters are received. Auto-baudrate detection is disabled when uart.setup
is called.
uart.alt()¶
Change UART pin assignment.
Syntax¶
uart.alt(on)
Parameters¶
on
- 0 for standard pins
- 1 to use alternate pins GPIO13 and GPIO15
Returns¶
nil
uart.on()¶
Sets the callback function to handle UART events.
Currently only the "data" event is supported.
Syntax¶
uart.on(method, [number/end_char], [function], [run_input])
Parameters¶
method
"data", data has been received on the UARTnumber/end_char
- if pass in a number n<255, the callback will called when n chars are received.
- if n=0, will receive every char in buffer.
- if pass in a one char string "c", the callback will called when "c" is encounterd, or max n=255 received.
function
callback function, event "data" has a callback like this:function(data) end
run_input
0 or 1. If 0, input from UART will not go into Lua interpreter, can accept binary data. If 1, input from UART will go into Lua interpreter, and run.
To unregister the callback, provide only the "data" parameter.
Returns¶
nil
Example¶
-- when 4 chars is received.
uart.on("data", 4,
function(data)
print("receive from uart:", data)
if data=="quit" then
uart.on("data") -- unregister callback function
end
end, 0)
-- when '\r' is received.
uart.on("data", "\r",
function(data)
print("receive from uart:", data)
if data=="quit\r" then
uart.on("data") -- unregister callback function
end
end, 0)
uart.setup()¶
(Re-)configures the communication parameters of the UART.
Syntax¶
uart.setup(id, baud, databits, parity, stopbits, echo)
Parameters¶
id
always zero, only one uart supportedbaud
one of 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 74880, 115200, 230400, 256000, 460800, 921600, 1843200, 3686400databits
one of 5, 6, 7, 8parity
uart.PARITY_NONE
,uart.PARITY_ODD
, oruart.PARITY_EVEN
stopbits
uart.STOPBITS_1
,uart.STOPBITS_1_5
, oruart.STOPBITS_2
echo
if 0, disable echo, otherwise enable echo
Returns¶
configured baud rate (number)
Example¶
-- configure for 9600, 8N1, with echo
uart.setup(0, 9600, 8, uart.PARITY_NONE, uart.STOPBITS_1, 1)
uart.write()¶
Write string or byte to the UART.
Syntax¶
uart.write(id, data1 [, data2, ...])
Parameters¶
id
always 0, only one UART supporteddata1
... string or byte to send via UART
Returns¶
nil
Example¶
uart.write(0, "Hello, world\n")