Input & Output data encoding

[phoddie]

Let's discuss how the payloads for read and write are handled.

For write, you convert the input string to a UTF-8 encoded buffer with "\n" appended:

this.#serial.write(ArrayBuffer.fromString(msg.payload + "\n"))

For read, you read all the bytes into a buffer, interpret that as UTF-8 to generate a JavaScript string, and then trim any whitespace from the end (including carriage returns):

let msg = String.fromArrayBuffer(this.read());
msg = msg.trimEnd()

These are both reasonable behaviors. But there are other reasonable behaviors. Node-RED provides many options

It provides a binary option, for situations where the data is not text. This is definitely useful, as many devices that use serial communicate in binary.

Node-RED doesn't use UTF-8. Instead, it uses ASCII. Serial is so old, it pre-dates Unicode so this is probably reasonable even if it seems old-fashioned.

Node-RED has an option to add a character at the end of a write ("Add character to output messages"). But, it is optional. This seems important since sometimes the app wants to control all the data.

Node-RED also has "framing" options -- "Optionally wait for a start character of " and "Split input". These are useful, but complicated.

Anyway... I think you might want to support some of the same options as Node-RED. Most are pretty straightforward to implement (I am happy to help) except for framing. But, I think first you should decide which capabilities are a priority.

[404background]

Thank you @phoddie ! I see, the binary option seems necessary.

For the options, I think it would be a good idea to implement it with reference to node-red-node-serialport. It will be easier for users if it can be used just like a serial node on a PC.

Here is the config option for the serial-port node:

I have one question. The "Serial Port" setting is different for serial communication between a microcontroller and a PC. Are there any other differences?

I will implement the binary option as a priority.

[phoddie]

Binary definitely makes sense as a next step.

But... have you seen this work by @ralphwetzel? I just discovered it today!

[404background]

I also discovered it today! In v1.5 of node-red-mcu-plugin , it says "Support for node-red-node-serialport on MCU's". https://github.com/ralphwetzel/node-red-mcu-plugin/releases/tag/v1.5

There seems to be some differences from node-red-node-serialport. I also will try to implement my node with reference to node-red-node-serialport!