https://github.com/mcauser/micropython-tca9548a
MicroPython examples using TCA9548A I2C multiplexer
https://github.com/mcauser/micropython-tca9548a
i2c micropython multiplexer tca9548a
Last synced: 3 months ago
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MicroPython examples using TCA9548A I2C multiplexer
- Host: GitHub
- URL: https://github.com/mcauser/micropython-tca9548a
- Owner: mcauser
- Created: 2020-09-27T11:46:11.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2020-09-27T11:47:51.000Z (about 5 years ago)
- Last Synced: 2025-04-04T15:50:01.388Z (7 months ago)
- Topics: i2c, micropython, multiplexer, tca9548a
- Homepage:
- Size: 2.95 MB
- Stars: 16
- Watchers: 2
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
Awesome Lists containing this project
- awesome-micropython - micropython-tca9548a - MicroPython examples using TCA9548A I2C multiplexer. (Libraries / IO)
README
# MicroPython TCA9548A 8-Channel I2C Multiplexer
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.
## Examples
```python
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')
```
## Two SSD1306 OLED displays
```python
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()
```
## I2C Address
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
## Parts
* [TinyPICO](https://www.tinypico.com/) $20.00 USD
* [TCA9548A CJMCU-9548](https://www.aliexpress.com/item/4000139869187.html) $1.23 AUD
## Connections
### TinyPICO ESP32
```python
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)
## Links
* [micropython.org](http://micropython.org)
* [TCA9548A datasheet](docs/tca9548a.pdf)
* [TinyPICO Getting Started](https://www.tinypico.com/gettingstarted)
## License
Licensed under the [MIT License](http://opensource.org/licenses/MIT).
Copyright (c) 2020 Mike Causer