Set RTS option and explain its effect

[michaelosthege]

I struggled with unreliable connection initialization with my ESP32-based panel.
The command line was sometimes all garbled up and sometimes not.

My ESP32 was restarting every time the COM port was opened/closed, and since it takes ~10 seconds to initialize, it wouldn't reliably establish the connection.

I found that DTS and RTS are both misused as a reset signal, and after setting RTS=off the restarts disappeared and the connection not initializes reliably.

To help other people I would propose to set the RTS option explicitly.

[charliefoxtwo]

Could you elaborate more on what the RTS option does? I'm not familiar with most of the arduino and COM stuff, but I haven't heard any reports about any other users experiencing the issue you've described so I'd be hesitant to merge something which - while it may fix an issue for one individual - may cause issues for many others.

I'm assuming based on your description that the RTS value is set to on by default so this PR doesn't actually change anything other than expose a new option which may help people, but if that's the case I'd appreciate it if you could link to additional documentation. Thanks!

[michaelosthege]

This thread explains the original purpose of these flags: https://stackoverflow.com/questions/957337/what-is-the-difference-between-dtr-dsr-and-rts-cts-flow-control

This thread shows a wiring diagram for ESP-8266 boards (https://arduino.stackexchange.com/a/52175) and explained that it's used to reset the microcontroller. Apparently that's the same for my ESP-32.

The mode command in the script sets the COM device setting, and for me it always printed RTS=on until I set the option. It's help shows:

mode /?
Configures system devices.

Serial port:       MODE COMm[:] [BAUD=b] [PARITY=p] [DATA=d] [STOP=s]
                                [to=on|off] [xon=on|off] [odsr=on|off]
                                [octs=on|off] [dtr=on|off|hs]
                                [rts=on|off|hs|tg] [idsr=on|off]

Unfortunately the documentation does not clarify the defaults either.

[charliefoxtwo]

I'm really hesitant to merge this without knowing what the default is.

It doesn't help that it's like impossible to look up anything for the command because it's named mode lol

[michaelosthege]

Could be that the default is whatever was previously set for that COM port.

Let's just keep the comment then, and not actually set the option.

[charliefoxtwo]

I'm all for improved documentation. The docs you linked also said hs | tg were valid options - did you want to add those as well (or maybe they just don't work in this context, I wouldn't know)?

[michaelosthege]

I understand that DCS-BIOS does not implement the interpretation of these signals, there fore I don't expect them to be useful at this point.