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I have connected an ssd1306 OLED and BME280 to my Pico. Everything works like a charm when connected to Pin 0 (sda) and 1 (scl) i2c pins. But due to my very bad planning, I have to switch to any other i2c pins. Once connected I cannot get it to work. I have changed from i2c = machine.I2C(0, scl=machine.Pin(1), sda=machine.Pin(0),freq=400000) to i2c = machine.I2C(0, scl=machine.Pin(13), sda=machine.Pin(12),freq=400000) and others, but to no avail. Code snippet:

import machine
import bme280
import time
from machine import Pin, I2C, ADC
from ssd1306 import SSD1306_I2C

i2c = machine.I2C(0, scl=machine.Pin(13), sda=machine.Pin(12),freq=400000)
bme = bme280.BME280(i2c=i2c)
oled = SSD1306_I2C(128, 64, i2c)

Error I'm getting is:

Traceback (most recent call last):   File "<stdin>", line 9, in <module>   File "/lib/bme280.py", line 75, in __init__ OSError: 5

Which is:

dig_88_a1 = self.i2c.readfrom_mem(self.address, 0x88, 26) from bme280.py (standard driver)

I have performed an i2c scan and it does return correct addresses on the new pins.

BDL
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imagine
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1 Answers1

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So I had a Similar Problem to you I had the ssd1306 OLED and I kept getting

\\Traceback (most recent call last):
  File "<stdin>", line 5, in <module>
  File "/lib/ssd1306.py", line 110, in __init__
  File "/lib/ssd1306.py", line 36, in __init__
  File "/lib/ssd1306.py", line 71, in init_display
  File "/lib/ssd1306.py", line 115, in write_cmd
OSError: [Errno 5] EIO

Im running the QT PI from addafuit but its a RP2040 chip and I'm running micro python.

Anyhow, I pressed the restart button on the board and It magically started working. Just like you, my i2c scan was getting the right address.

the code I ended up using that worked for me was

from machine import Pin, I2C
from ssd1306 import SSD1306_I2C

i2c = I2C(0,sda=Pin(24),scl=Pin(25),freq=40000)
oled = SSD1306_I2C(128,64,i2c)


oled.fill(0)

oled.text("Hello",0,0)

oled.show()

and for the ssd1306 driver, I used

# MicroPython SSD1306 OLED driver, I2C and SPI interfaces

from micropython import const
import framebuf


# register definitions
SET_CONTRAST = const(0x81)
SET_ENTIRE_ON = const(0xA4)
SET_NORM_INV = const(0xA6)
SET_DISP = const(0xAE)
SET_MEM_ADDR = const(0x20)
SET_COL_ADDR = const(0x21)
SET_PAGE_ADDR = const(0x22)
SET_DISP_START_LINE = const(0x40)
SET_SEG_REMAP = const(0xA0)
SET_MUX_RATIO = const(0xA8)
SET_COM_OUT_DIR = const(0xC0)
SET_DISP_OFFSET = const(0xD3)
SET_COM_PIN_CFG = const(0xDA)
SET_DISP_CLK_DIV = const(0xD5)
SET_PRECHARGE = const(0xD9)
SET_VCOM_DESEL = const(0xDB)
SET_CHARGE_PUMP = const(0x8D)

# Subclassing FrameBuffer provides support for graphics primitives
# http://docs.micropython.org/en/latest/pyboard/library/framebuf.html
class SSD1306(framebuf.FrameBuffer):
    def __init__(self, width, height, external_vcc):
        self.width = width
        self.height = height
        self.external_vcc = external_vcc
        self.pages = self.height // 8
        self.buffer = bytearray(self.pages * self.width)
        super().__init__(self.buffer, self.width, self.height, framebuf.MONO_VLSB)
        self.init_display()

    def init_display(self):
        for cmd in (
            SET_DISP | 0x00,  # off
            # address setting
            SET_MEM_ADDR,
            0x00,  # horizontal
            # resolution and layout
            SET_DISP_START_LINE | 0x00,
            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
            # charge pump
            SET_CHARGE_PUMP,
            0x10 if self.external_vcc else 0x14,
            SET_DISP | 0x01,
        ):  # on
            self.write_cmd(cmd)
        self.fill(0)
        self.show()

    def poweroff(self):
        self.write_cmd(SET_DISP | 0x00)

    def poweron(self):
        self.write_cmd(SET_DISP | 0x01)

    def contrast(self, contrast):
        self.write_cmd(SET_CONTRAST)
        self.write_cmd(contrast)

    def invert(self, invert):
        self.write_cmd(SET_NORM_INV | (invert & 1))

    def show(self):
        x0 = 0
        x1 = self.width - 1
        if self.width == 64:
            # displays with width of 64 pixels are shifted by 32
            x0 += 32
            x1 += 32
        self.write_cmd(SET_COL_ADDR)
        self.write_cmd(x0)
        self.write_cmd(x1)
        self.write_cmd(SET_PAGE_ADDR)
        self.write_cmd(0)
        self.write_cmd(self.pages - 1)
        self.write_data(self.buffer)


class SSD1306_I2C(SSD1306):
    def __init__(self, width, height, i2c, addr=0x3C, external_vcc=False):
        self.i2c = i2c
        self.addr = addr
        self.temp = bytearray(2)
        self.write_list = [b"\x40", None]  # Co=0, D/C#=1
        super().__init__(width, height, external_vcc)

    def write_cmd(self, cmd):
        self.temp[0] = 0x80  # Co=1, D/C#=0
        self.temp[1] = cmd
        self.i2c.writeto(self.addr, self.temp)

    def write_data(self, buf):
        self.write_list[1] = buf
        self.i2c.writevto(self.addr, self.write_list)


class SSD1306_SPI(SSD1306):
    def __init__(self, width, height, spi, dc, res, cs, external_vcc=False):
        self.rate = 10 * 1024 * 1024
        dc.init(dc.OUT, value=0)
        res.init(res.OUT, value=0)
        cs.init(cs.OUT, value=1)
        self.spi = spi
        self.dc = dc
        self.res = res
        self.cs = cs
        import time

        self.res(1)
        time.sleep_ms(1)
        self.res(0)
        time.sleep_ms(10)
        self.res(1)
        super().__init__(width, height, external_vcc)

    def write_cmd(self, cmd):
        self.spi.init(baudrate=self.rate, polarity=0, phase=0)
        self.cs(1)
        self.dc(0)
        self.cs(0)
        self.spi.write(bytearray([cmd]))
        self.cs(1)

    def write_data(self, buf):
        self.spi.init(baudrate=self.rate, polarity=0, phase=0)
        self.cs(1)
        self.dc(1)
        self.cs(0)
        self.spi.write(buf)
        self.cs(1)

So the only advice and can give to you is to try to press the restart button.

  • Man I was stuck with this for about 4 hrs and your advice worked, in case somebody happens to pass through the same please remember to disconnect your device from your computer and then plug it again, seems like it has something to do with it, thank you Caleb! – Rodolfo BocaneGra Sep 02 '23 at 23:47