esp32 CYD (xpt2046) button callback not firing

[tedx]

I'm having trouble getting button click callbacks to fire any idea what I'm doing wrong?

import gc

mem_free_startup = gc.mem_free()

import lvgl as lv
import lcd_bus
import ili9341
import xpt2046
from machine import SPI, Pin
import i2c
import machine
import micropython
import task_handler

_DISPLAY_WIDTH = micropython.const(320)
_DISPLAY_HEIGHT = micropython.const(240)
_DISPLAY_ROT = micropython.const(0x80)
_DISPLAY_BGR = micropython.const(0)
_DISPLAY_RGB565_BYTE_SWAP = micropython.const(1)
_ALLOW_TOUCH_CAL = micropython.const(1)
_DISPLAY_SHOW_TOUCH_INDICATOR = micropython.const(1)

_SPI_BUS_HOST = micropython.const(1)
_SPI_BUS_MOSI = micropython.const(13)
_SPI_BUS_MISO = micropython.const(12)
_SPI_BUS_SCK = micropython.const(14)
_INDEV_BUS_HOST = micropython.const(2)
_INDEV_BUS_MOSI = micropython.const(32)
_INDEV_BUS_MISO = micropython.const(39)
_INDEV_BUS_SCK = micropython.const(25)
_INDEV_DEVICE_FREQ = micropython.const(2000000)
_INDEV_DEVICE_CS = micropython.const(33)
_DISPLAY_BUS_FREQ = micropython.const(24000000)
_DISPLAY_BUS_DC = micropython.const(2)
_DISPLAY_BUS_CS = micropython.const(15)
_DISPLAY_BACKLIGHT_PIN = micropython.const(21)

spi_bus = machine.SPI.Bus(
    host=_SPI_BUS_HOST,
    mosi=_SPI_BUS_MOSI,
    miso=_SPI_BUS_MISO,
    sck=_SPI_BUS_SCK
)

indev_bus = machine.SPI.Bus(
    host=_INDEV_BUS_HOST,
    mosi=_INDEV_BUS_MOSI,
    miso=_INDEV_BUS_MISO,
    sck=_INDEV_BUS_SCK
)

indev_device = machine.SPI.Device(
    spi_bus=indev_bus,
    freq=_INDEV_DEVICE_FREQ,
    cs=_INDEV_DEVICE_CS
)

display_bus = lcd_bus.SPIBus(
    spi_bus=spi_bus,
    freq=_DISPLAY_BUS_FREQ,
    dc=_DISPLAY_BUS_DC,
    cs=_DISPLAY_BUS_CS
)

display = ili9341.ILI9341(
    data_bus=display_bus,
    display_width=_DISPLAY_WIDTH,
    display_height=_DISPLAY_HEIGHT,
    backlight_pin=_DISPLAY_BACKLIGHT_PIN,
    backlight_on_state=ili9341.STATE_PWM,
    color_space=lv.COLOR_FORMAT.RGB565,
    color_byte_order=ili9341.BYTE_ORDER_BGR if _DISPLAY_BGR else ili9341.BYTE_ORDER_RGB,
    rgb565_byte_swap=_DISPLAY_RGB565_BYTE_SWAP
)

display._ORIENTATION_TABLE = (
    _DISPLAY_ROT, # this value sets the rotation
    0x0, # placeholder
    0x0, # placeholder
    0x0 # placeholder
)

display.set_rotation(lv.DISPLAY_ROTATION._0)
display.set_power(True)
display.init(1)
display.set_backlight(100)

indev = xpt2046.XPT2046(device=indev_device)

scrn = lv.screen_active()
scrn.set_style_bg_color(lv.color_black(), lv.PART.MAIN)
scrn.remove_flag(lv.obj.FLAG.SCROLLABLE)

agitate_btn = lv.button(scrn)
agitate_btn.add_flag(lv.obj.FLAG.CLICKABLE)
agitate_label = lv.label(agitate_btn)
agitate_label.set_text("Agitate")

stop_btn = lv.button(scrn)
stop_btn.add_flag(lv.obj.FLAG.CLICKABLE)
stop_label = lv.label(stop_btn)
stop_label.set_text("Stop")
agitate_btn.align(lv.ALIGN.CENTER, -50, 0)
stop_btn.align(lv.ALIGN.CENTER, 50, 0)

def button_event_handler(evt):
    print("button_event_handler")
    obj = evt.get_target_obj()
    if obj == agitate_btn:
        print("Agitate clicked")
    else:
        print("Stop clicked")

agitate_btn.add_event_cb(button_event_handler, lv.EVENT.CLICKED, None)
stop_btn.add_event_cb(button_event_handler, lv.EVENT.CLICKED, None)

task_handler.TaskHandler()

[kdschlosser]

I would suggest creating a separate callback for each object this way you don't need to do a comparison of the objects in the event. doing that gets tricky because you need to cast the object that is collected using get_target_obj to the type it originally was. LVGL is written so widgets extend a base structure which is lv_obj_t. so that is what is always returned when calling that function. You would need to turn it back into it's original type to perform an equality test on it.

[tedx]

Certainly I can do that but I'm not even seeing the "button_event_handler" print so it doesn't appear that the callback is being called. How does lvgl know about the touch device? I create a XPT2046 object 'indev' but how does it get associated with input widgets like buttons?

[kdschlosser]

That specific touch panel is a resistive touch panel. Have you performed a calibration at all??

indev = xpt2046.XPT2046(device=indev_device)
if not indev.is_calibrated:
    indev.calibrate()

[tedx]

No, I'll add that code.

[tedx]

Thanks that did the trick.

[kdschlosser]

Awesome.. The XPT touch screen need to have a calibration done on them because they can be glued to the screen upside down and things like that. Basically you were touching but LVGL wasn't seeing the touch as hitting on the button which is why you were having an issue.