node-red & ble uart

Hi @Gordon,

How can Puck's UART service be connected from node-red ?

I have installed https://www.npmjs.com/package/node-red-c­ontrib-ble-uart and created a sample workflow as suggested, but Puck does not appear. Any thoughts ?

Thank you!

I usually use EspruinoHub to bridge from MQTT.

However one of the steps to set up Noble (the lib that contrib-blue-uart probably uses) is to run the command:

sudo setcap cap_net_raw+eip $(eval readlink -f `which node`)

Have you done that? It might help? If node doesn't exist you might have to change it to which nodejs

Hi @Gordon,

I would like to call a function on Puck from node-red. Am I on the right way with contrib-blue-uart or that could be done with EspruinoHub too ?

Thank you!

Either way will work. contrib-blue-uart is a less Espruino-specific way that doesn't require a separate service, but EspruinoHub will be able to pick up advertising data and report it back via MQTT.

Info on using EspruinoHub to send commands to Puck.js here: http://www.espruino.com/Puck.js+Node-RED­

Hi @Gordon,

I have used your advises in the link above to build my flows. But now I need to call a function called "myFunc" on the specific Puck and read the result rather than reading the advertised data. How can I do that ?

Thank you!

Ahh - I'm afraid that functionality isn't built in to EspruinoHub yet.

You might be able to do a write to /ble/write/_address_/nus/nus_tx followed by a write (contents don't matter) to /ble/read/_address_/nus/nus_rx after a delay, and then listen on /ble/data/_address_/nus/nus_rx but that would only return the last 18 characters or so of response (plus some formatting characters).

To make it better you could ensure you send "\x10print(your_function())" (that's character code 16 at the start) - which will ensure that the data you receive is only the data your function returned.

However in this case, you're probably better off using contrib-blue-uart - did you get it working?

The advice above ("\x10print(your_function())") will still help you though.

Hi @Gordon,

I am using https://www.npmjs.com/package/node-red-c­ontrib-ble-uart
Here on the sample workflow there is a On/Off input to BLE followed by ToString function dumped on the output.

I cannot make it scanning even with the advises above. Once done, how can I send the command to the specific Puck with xx:xx:xx:xx:xx:xx address ?

Thanks!

I've just tried node-red-contrib-ble-uart and node-red-contrib-ble, and I can't make either of them work properly (although node-red-contrib-ble actually looks more promising).

Not sure what to suggest really - you could contact the authors of those modules/post on their GitHub pages? Puck.js is a standard Nordic UART device, so they should definitely be able to work.

Hi @Gordon,

No response from both owners of UART modules for node-red. Now complex is that to appear in EspruinoHub ?

Thank you!

It shouldn't be too hard to add - are you interested in trying to do it yourself?

I'd:

• Add an eval function to connect (https://github.com/espruino/EspruinoHub/­blob/master/lib/connect.js#L39) that mashes together the read and write functionality (connect, listen for notifications, write, then wait a bit and return anything returned from notifications).
  
• Add a check for eval in the path to https://github.com/espruino/EspruinoHub/­blob/master/lib/mqttclient.js#L53 and make that call your eval function, and then send the result of that back as something like /ble/address/result.