USB transport

[phoddie]

This issue is for discussion of using runmod with WebUSB.

I pushed changes to runmod today that provide the same functionality over USB as is available using WebSockets. The documentation has been updated with the relevant details throughout. The xsbug.js example has been updated with WebUSB support including separate new XsbugUSB and XsbugWebSocket classes to manage the two connection types.

[FWeinb]

@phoddie
I looked into it but I can't get it to work. I reapplied the patches and build runmod new.

I tested it with the provided example but noticed that there is a typo in line 79. But that is not the problem. I enabled the tracePacket function (changing the data here to tracePacket("> ", new Uint8Array(result.data.buffer));)

After the above fixes where applied I got this trace output.

I don't know if this is related but I get this message when unloading the driver but the WebUSB connection is established. If I load the driver again I can't connect to the device, so unloading seams to work.

sudo kextunload -b com.silabs.driver.CP210xVCPDriver
(kernel) Can't unload kext com.silabs.driver.CP210xVCPDriver; classes have instances:
(kernel)     Kext com.silabs.driver.CP210xVCPDriver class com_silabs_CP210xGPIO has 2 instances.
Failed to unload com.silabs.driver.CP210xVCPDriver - (libkern/kext) kext is in use or retained (cannot unload). 

[phoddie]

Thanks for giving it a try. Sorry about the typo. I'll fix that. It must have crept in when merging.

The driver isn't unloaded if there are still instances reported by kextunload. Let's fix that first. Sometimes there are zombie instances in the terminal. Try quitting terminal, restarting it, and then unloading again. If that fails, reboot and try again.

Once you are running, make sure the set the baud rate for your microcontroller at line 608. It is configured for ESP32 here. If you are using ESP8266 you will need to remove the divide by two.

[FWeinb]

@phoddie
Right after I hit send I noticed that it was configured for the ESP32. I tested with the moddable zero. Changeing to 921600 fixed everything. The kextunload seams not to be the issue.

[FWeinb]

@phoddie
There seams to be another xsbug message type called parsererror that is not implemented yet. I am getting TypeError: XsbugMessage[node.nodeName] is not a function

[Edit]
I see. This is the behaviour of the DOMParser. There seams to be a malformed XML document. the DOMParser will insert the parsererror node into the document.

[Edit2]
I am getting malformed usb transmission. There are intermitted random numbers or missing text in the XML.

[phoddie]

@FWeinb - as noted in the code, WebUSB itself doesn't seem to do much buffering itself. That can lead to dropped characters. One option is to slow down the connection, which is easy but undesirable as it makes everything slower. Another is to increase the buffer size. It is reliable for me as committed but your computer may be different. The revive buffer is set to 32 KB at line 234. The USB read size is set to 32 KB at line 328. Try making both of them much bigger, say 128 KB.

[FWeinb]

@phoddie
That had no effect. Still getting corrupt USB data.

[Edit]
Here is an example document (formatted)

[FWeinb]

@phoddie
That is strange! Commenting out the tracePacket function solved the issue. But not completely. Sometimes I still get broken data.

[FWeinb]

@phoddie
Okay. Sorry for spamming this thread, figured it out. I compiled the runmod without WiFi support but mdns is still trying to publish the hostname. That lead to UDP send errors that crashed the device and broke the USB connection.

[phoddie]

Good catch. I'll look at fixing runmod so it doesn't assume there is a network connection. Until yesterday, that was a safe assumption. ;)

[FWeinb]

@phoddie
Just FYI the arguments of padStart must be swapped here.

[phoddie]

Update to main.js pushed to only start the mDNS and WebSocket services if there is a Wi-Fi connection. You'll need to update the Moddable SDK for that to work properly on ESP8266.

[FWeinb]

@phoddie
I pushed a new version that supports both WiFi and USB connections. After some initial problems everything seems to work fine. It is a little strange that one has to unload the driver but understandable as the WebUSB spec seams very low level in regards to handling devices.

The best part is that WebUSB is working over https without any warnings!

Could not test with the latest changes you committed. It is way to late (early) here.

[phoddie]

That was very quick! I will check it out later. Get some rest.

It is a little strange that one has to unload the driver but understandable as the WebUSB spec seams very low level in regards to handling devices.

It isn't perfect. For beginning users, that may be just fine. The IDE may be able to provide guidance to users when the driver is installed. I have a trace in the example in that case, for example.

The best part is that WebUSB is working over https without any warnings!

Wahoo!

[FWeinb]

The IDE may be able to provide guidance to users when the driver is installed

That sounds like a great idea. I copied your error message and show it in the Log panel but that message could be improved.

Any idea what the implementation status of WebUSB is for Firefox? It seams that Chrome is the only browser shipping this API.

[phoddie]

I copied your error message and show it in the Log panel but that message could be improved.

Since the browser knows the host OS, it could provide pretty specific advice.

Any idea what the implementation status of WebUSB is for Firefox? It seams that Chrome is the only browser shipping this API.

As far as I know, no other browser has indicated an intent to support it. And all the editors of the WebUSB specification are from Google. ;)