Getting the unPhone working.

[jedie]

I have a unPhone (spin 9) and tried to get MicroPythonOS working: MicroPythonOS/MicroPythonOS#74

Display HX8357D and XPT2046 touch works in general, but currently not together.
Seems the Problem is that both used the same SPI bus.

My setup is like: https://github.com/lvgl-micropython/lvgl_micropython?tab=readme-ov-file#spi-bus-with-spi-touch-same-spi-bus

If i use SPI Bus host = 1 for display + touch, then the touch registers are always 0xff
If i use SPI Bus host =1 for display and host = 2 for touch, then the registers are always 0x00

In both cases: The Display work.

I also tried chip select (T_CS) of touch screen, before read, but doesn't change anything.

Any idea?

EDIT: Sound like https://dmitry.gr/?r=06.%20Thoughts&proj=09.ComplexPioMachines described a similar problem.

i also tried this:

    def _read_reg(self, reg, num_bytes) -> int:
        try:
            for read_count in range(50):
                self._tx_buf[0] = reg

                self.lcd_cs.value(1)  # deselect LCD to avoid conflicts
                self.touch_cs.value(0)  # select touch chip
                self.device.write_readinto(
                    self._tx_mv[:num_bytes], self._rx_mv[:num_bytes]
                )
                if self.lcd_cs.value() == 1 and self.touch_cs.value() == 0:
                    # if still selected, we got a valid read
                    break
        finally:
            self.touch_cs.value(1)  # deselect touch chip
            self.lcd_cs.value(0)  # select LCD

        print(
            f"write_readinto {read_count=}"
            f" Channel: {reg:#04x}, Received: {[hex(b) for b in self._rx_buf]}"
        )
        return ((self._rx_buf[1] << 8) | self._rx_buf[2]) >> 3

But doesn't help, the output is always:

write_readinto read_count=0 Channel: 0xb0, Received: ['0x0', '0x0', '0x0']
write_readinto read_count=0 Channel: 0xd0, Received: ['0x0', '0x0', '0x0']
write_readinto read_count=0 Channel: 0x90, Received: ['0x0', '0x0', '0x0']

A other idea:

    def _read_reg(self, reg, num_bytes) -> int:

        # First read to get reference:
        self._tx_buf[0] = reg
        self.device.write_readinto(
            self._tx_mv[:num_bytes], self._rx_mv[:num_bytes]
        )
        reference = self._rx_buf[:num_bytes]
        
        try:
            for read_count in range(50):
                self._tx_buf[0] = reg

                self.lcd_cs.value(1)  # deselect LCD to avoid conflicts
                self.touch_cs.value(0)  # select touch chip
                self.device.write_readinto(
                    self._tx_mv[:num_bytes], self._rx_mv[:num_bytes]
                )
                if self._rx_buf[:num_bytes] != reference:
                    # we got a valid read
                    break
        finally:
            self.touch_cs.value(1)  # deselect touch chip
            self.lcd_cs.value(0)  # select LCD

        print(
            f"write_readinto {read_count=}"
            f" Channel: {reg:#04x}, Received: {[hex(b) for b in self._rx_buf]}"
        )
        return ((self._rx_buf[1] << 8) | self._rx_buf[2]) >> 3

Also doesn't help:

 write_readinto read_count=49 Channel: 0xb0, Received: ['0x0', '0x0', '0x0']
write_readinto read_count=49 Channel: 0xd0, Received: ['0x0', '0x0', '0x0']
write_readinto read_count=49 Channel: 0x90, Received: ['0x0', '0x0', '0x0']

[jedie]

OK,i get it working. The trick is to use the same SPI bus and not different hosts.

But i need to expand the https://github.com/lvgl-micropython/lvgl_micropython/blob/main/api_drivers/common_api_drivers/indev/xpt2046.py here: https://github.com/MicroPythonOS/MicroPythonOS/pull/74/changes#diff-65d1066e20796b04f7d3bf45c5a5929abec1e82acaa7b00c802ff783658b6178

The major change it to manage the LCD and Touch CS pins in _get_coords()

@kdschlosser Think it's a good idea to bring this upstream. But how to merge this here? One idea is to make the added arguments lcd_cs and touch_cs optional and check if they are set in _get_coords(). But this is a little overhead, isn't it? Any other idea?