A MicroPython library for the CJMCU-9548 module, featuring the TCA9548A. This module lets you run multiple I2C devices with the same address on the bus, by spreading the conflicting devices across 8 channels and toggling between them.
The module itself is present on the I2C bus with a configurable address of 0x70-0x77 using the A0,A1,A2 pins. This lets you daisy chain them and have up to 64 devices on the bus with the same address.
It features a single 8-bit register, where each bit enables each of the 8 channels. I2C channel 0 is enabled with the LSB and channel 7 with the MSB. You can also enable multiple channels at the same time.
from machine import I2C, Pin
i2c = I2C(scl=Pin(22), sda=Pin(21))
# disable all 8 channels
i2c.writeto(0x70, b'\x00')
i2c.scan()
# [112] - the TCA9548A
# enable channel 0 (SD0,SC0)
i2c.writeto(0x70, b'\x01')
i2c.scan()
# [60, 112] - Display 1 (SSD1306) & TCA9548A
# enable channel 1 (SD1,SC1)
i2c.writeto(0x70, b'\x02')
i2c.scan()
# [60, 112] - Display 2 (SSD1306) & TCA9548A
# enable channels 0 (SD0,SC0) & 2 (SD2,SC2)
i2c.writeto(0x70, b'\x05')
i2c.scan()
# [60, 68, 112] - Display 1 (SSD1306) & SHT31 sensor & TCA9548A
# read which channels are enabled?
i2c.readfrom(0x70, 1)
# b'\x05' - channels 0 and 2 (0x05 == 0b_0000_0101)
# enable all 8 channels
i2c.writeto(0x70, b'\xff')
# disable all 8 channels
i2c.writeto(0x70, b'\x00')
from machine import I2C, Pin
i2c = I2C(scl=Pin(22), sda=Pin(21))
i2c.scan()
# [112]
# enable channel 0 (SD0,SC0)
i2c.writeto(0x70, b'\x01')
i2c.scan()
# [60, 112]
import ssd1306
oled = ssd1306.SSD1306_I2C(128, 64, i2c)
# write to the first display
oled.fill(0)
oled.text('Display 1', 0, 0, 1)
oled.show()
# enable channel 1 (SD1,SC1)
i2c.writeto(0x70, b'\x02')
# init the second display
oled.init_display()
# write to the second display
oled.fill(0)
oled.text('Display 2', 0, 0, 1)
oled.show()
# enable channels 0 (SD0,SC0) & 1 (SD1,SC1)
i2c.writeto(0x70, b'\x03')
# write to the both displays
oled.fill(0)
oled.text('Hello', 0, 0, 1)
oled.show()There are three address select pins (A0,A1,A2) providing addresses 0x70-0x77 for up to 8 of these devices on the I2C bus.
The CJMCU-9548 module has pull-downs on the 3x address select pins, so you only need to connect them to VCC to change the address.
| A0 | A1 | A2 | I2C Address |
|---|---|---|---|
| GND | GND | GND | 0x70 |
| 3V3 | GND | GND | 0x71 |
| GND | 3V3 | GND | 0x72 |
| 3V3 | 3V3 | GND | 0x73 |
| GND | GND | 3V3 | 0x74 |
| 3V3 | GND | 3V3 | 0x75 |
| GND | 3V3 | 3V3 | 0x76 |
| 3V3 | 3V3 | 3V3 | 0x77 |
- TinyPICO $20.00 USD
- TCA9548A CJMCU-9548 $1.23 AUD
from machine import Pin, I2C
i2c = I2C(scl=Pin(22), sda=Pin(21))| TCA9548A | TinyPICO (ESP32) |
|---|---|
| VIN | 3V3 |
| GND | GND |
| SCL | 22 (SCL) |
| SDA | 21 (SDA) |
Licensed under the MIT License.
Copyright (c) 2020 Mike Causer