heartrate example panic

[gitchander]

I have next problem with standard example of heartrate-monitor:

panic: interface conversion: interface {} is map[string]map[string]dbus.Variant, not dbus.ObjectPath

goroutine 1 [running]:
tinygo.org/x/bluetooth.(*Adapter).Scan(0x786c00, 0xc0000bdea8)
.../pkg/mod/tinygo.org/x/bluetooth@v0.8.0/gap_linux.go:177 +0xeb7

How I can fix it?

[TirelessDev]

Can you provide a bit more information, please?

What are you running this on?
Are you using the latest release or a branch?
What version of DBus are you running?

Cheers

[gitchander]

I do it on:
os Ubuntu 22.04.3 LTS

Adapter USB Bluetooth 5.1 USB 2.0 RTL8761B Chip

I used last version, not branch.

go.mod file:

go 1.21.0

require tinygo.org/x/bluetooth v0.8.0

require (
github.com/fatih/structs v1.1.0 // indirect
github.com/go-ole/go-ole v1.3.0 // indirect
github.com/godbus/dbus/v5 v5.1.0 // indirect
github.com/muka/go-bluetooth v0.0.0-20221213043340-85dc80edc4e1 // indirect
github.com/saltosystems/winrt-go v0.0.0-20230921082907-2ab5b7d431e1 // indirect
github.com/sirupsen/logrus v1.9.3 // indirect
github.com/tinygo-org/cbgo v0.0.4 // indirect
golang.org/x/sys v0.12.0 // indirect
)

go.sum file:

tinygo.org/x/bluetooth v0.7.0 h1:7lU0VrauwccbLvb6AKHf4ZedFlxZIFwwqHWQD2fLWvA=
tinygo.org/x/bluetooth v0.7.0/go.mod h1:2hZPpfPDMR7Vvi6yMvyi83o8gYXeMKKsLfUnvmtBcjM=
tinygo.org/x/bluetooth v0.8.0 h1:WmuRebsODcUUIlGhesyuNRIAEIUCErhKlrZ9K9aimdI=
tinygo.org/x/bluetooth v0.8.0/go.mod h1:cfsVc0/nGo3nzi6+CeQaXb+anNlmEnSABkKsxer8OAE=

[TirelessDev]

Sweet thanks, what does bluetoothctl -v say?

[gitchander]

bluetoothctl: 5.64

[TirelessDev]

Okay, very peculiar. Everything checks out with the versions that I can see.

The panic seems to suggest that the dbus object that has been provided in the org.freedesktop.DBus.ObjectManager.InterfacesAdded signal is somehow backwards with the Variant map in index 0 and the object path in index 1. I have no idea how that would happen though.

bluetooth/gap_linux.go

Lines 177 to 178 in d0c7887

	objectPath := sig.Body[0].(dbus.ObjectPath)
	interfaces := sig.Body[1].(map[string]map[string]dbus.Variant)

maybe try monitor dbus with sudo busctl monitor org.bluez | grep -A4 "InterfacesAdded" you should get something like the following show up when new devices are found during the scan.

  Sender=:1.212  Path=/  Interface=org.freedesktop.DBus.ObjectManager  Member=InterfacesAdded
  UniqueName=:1.212
  MESSAGE "oa{sa{sv}}" {
          OBJECT_PATH "/org/bluez/hci0/dev_XX_XX_XX_XX_XX_XX";
          ARRAY "{sa{sv}}" {

You can also manually enable a scan without running any go code with the command bluetoothctl scan on.

[gitchander]

I scanned and connected to BlueNRG-345 (dev kit STEVAL-IDB), discovered services and read characteristics. There was no problem.

[gitchander]

len(sig.Body) => 1
sig.Body[0] type is "map[string]map[string]dbus.Variant"

map key "org.bluez.GattService1"
map values:
"Handle": @q 0
"Primary": true
"UUID": "0000180d-0000-1000-8000-00805f9b34fb"
"Characteristics": @ao []

[TirelessDev]

Not too sure what could be going on then. If you haven't already I would try reinstalling BlueZ or maybe trying a different version.

[gitchander]

Can I run heartrate server and client on one PC?

[deadprogram]

Very good chance this is now fixed by #216 which was merged into dev branch.

[aykevl]

Can I run heartrate server and client on one PC?

No. But you can use a smartphone app, for example "nRF Connect" on Android.
(I'm personally also using a Raspberry Pi for testing such stuff as a 2nd system).

@gitchander is this still a bug?

[gitchander]

If you start the client first and then start the server on the same PC, this will still lead to panic. Maybe this can be fixed.
Thanks for your answer!