GUI Guider (LVGL v9 simulator) FreeMASTER binding: Meter with Image Needle disappears GG_METER h

ryan_hong_wtmec — Tue, 23 Dec 2025 00:59:22 GMT

Hi all,
I’d like to share an issue and workaround for GUI Guider + LVGL v9 simulator with FreeMASTER binding.

Environment: GUI Guider 9.2 / 1.10.0 GA, LVGL v9 simulator (lvgl-simulator or lv_web_emscripten),
FreeMASTER JSON-RPC WebSocket (ws://localhost:41000), Windows 10/11.

Problem: When a FreeMASTER variable is bound to a Meter/Scale widget using an Image Needle,
the needle disappears or does not update correctly. The same variable bound to a Label updates
normally (e.g., 40–60), so the incoming value is valid.

Workaround/Fix: Patch the simulator code (or the template) here:
C:\nxp\GUI-Guider-1.10.0-GA\environment\template\project\v9\lvgl-simulator\gg_external_data\freemaster\freemaster_client.c

Update the GG_METER case to safely handle image needles vs line needles (and add NULL guards):

case GG_METER:
{
for (int i = 0; i < user_parm->arrayLen; i++)
{
meter_needle *nd = (meter_needle *)user_parm->childObjArray[i];
int v = atoi(dataArray[i]);

if (nd && nd->needle_obj)
{
if (lv_obj_check_type(nd->needle_obj, &lv_image_class))
lv_scale_set_image_needle_value(user_parm->parentObj, nd->needle_obj, v);
else
lv_scale_set_line_needle_value(user_parm->parentObj, nd->needle_obj, nd->needle_length, v);
}
}
break;
}

Question: Is this a known issue? If not, could this fix be integrated into future GUI Guider releases/templates?

Thanks.

Re: GUI Guider (LVGL v9 simulator) FreeMASTER binding: Meter with Image Needle disappears GG_METER

Celeste_Liu — Tue, 23 Dec 2025 04:07:13 GMT

Hello @ryan_hong_wtmec ,

Thank you for sharing. I will report this to the internal team and wait for their further confirmation.

Thank you for again your contribution in the NXP community.

Celeste

MCX MicrocontrollersのトピックGUI Guider (LVGL v9 simulator) FreeMASTER binding: Meter with Image Needle disappears GG_METER h

GUI Guider (LVGL v9 simulator) FreeMASTER binding: Meter with Image Needle disappears GG_METER h

Re: GUI Guider (LVGL v9 simulator) FreeMASTER binding: Meter with Image Needle disappears GG_METER