uart.start(tx, rx, baud)
Starts asynchronous communication using UART.
To initialize the communication, specify the IO pin numbers for TX (transmit) and RX (receive), along with the baud rate (communication speed).
- tx: IO pin number for transmission from your obniz Device.
- rx: IO pin number for reception to your obniz Device.
- baud: Communication speed (e.g., 9600, 115200).
uart.send(string)
Sends data through the initialized UART interface.
This function is synchronous; it will wait and block further execution until the data transmission is completely finished.
uart.recv()
Received data is automatically stored in an internal buffer. You can retrieve this accumulated data by calling uart.recv().
Example
The following example demonstrates how to receive UART data and send it to the cloud. This script is designed to handle data even if it was received while the device was offline; once the connection is established, the data will be uploaded to the cloud sequentially.
```lua
os.log(" - Lua Start");
-- Set IO pins to retain their state
io.retain(1, true);
io.retain(2, true);
-- Initialize UART on IO1 (TX) and IO2 (RX) at 115200 baud
uart.start(1, 2, 115200);
-- Send initial message
uart.send("Hello World");
function on_online_loop()
-- Retrieve received data from the buffer
local ret = uart.recv();
-- Example: Limit receive buffer to 1 byte
-- local ret = uart.recv(1);
if #ret > 0 then
-- Echo back the received data via UART and also send it to the cloud
uart.send(ret);
cloud.pluginSend(ret);
end
end