SSD1306 GUI driver and SET_IREF_SELECT

[gvdl]

G'day, All.

I've been looking around at various ssd1306 µpy drivers and have generally found that they initialise the SET_IREF_SELECT register to 0x30. According to my searching this is to avoid flickering with current ssd1306 displays (read cheap knockoff implementations of .96" BOB).

As I'm in code reading phase I noticed that the nano-gui/drivers for the ssd1306 does not initialise this register during it's init instantiation. Having been wrong before when shooting from the hip I'm hesitant to create an issue.

However, Peter, if you'd like I'm happy to create a PULL request and an Issue that does do the init.

    def init_display(self):
        for cmd in (
            SET_DISP,  # display off
            # address setting
            SET_MEM_ADDR,
            0x00,  # horizontal
            # resolution and layout
            SET_DISP_START_LINE,  # start at line 0
            SET_SEG_REMAP | 0x01,  # column addr 127 mapped to SEG0
            SET_MUX_RATIO,
            self.height - 1,
            SET_COM_OUT_DIR | 0x08,  # scan from COM[N] to COM0
            SET_DISP_OFFSET,
            0x00,
            SET_COM_PIN_CFG,
            0x02 if self.width > 2 * self.height else 0x12,
            # timing and driving scheme
            SET_DISP_CLK_DIV,
            0x80,
            SET_PRECHARGE,
            0x22 if self.external_vcc else 0xF1,
            SET_VCOM_DESEL,
            0x30,  # 0.83*Vcc
            # display
            SET_CONTRAST,
            0xFF,  # maximum
            SET_ENTIRE_ON,  # output follows RAM contents
            SET_NORM_INV,  # not inverted
            SET_IREF_SELECT,
            0x30,  # enable internal IREF during display on
            # charge pump
            SET_CHARGE_PUMP,
            0x10 if self.external_vcc else 0x14,
            SET_DISP | 0x01,  # display on
        ):  # on
            self.write_cmd(cmd)
        self.fill(0)
        self.show()

Where

SET_IREF_SELECT = const(0xAD)

Note that I haven't been able to find the 0xad register declared in any datasheets for this underlying chipset so I'm not sure if this is appropriate

[peterhinch]

This driver is derived from the official SSD1306 driver, with only trivial changes. I suggest you raise an issue against this. If the change is accepted then I will happily incorporate it into this driver.

[gvdl]

That makes sense, I'll have a look at the official driver

Done micropython/micropython-lib#1025