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Add support for 16 Channel I2C Electromagnetic Relay Module IoT
Using PCF8575 chip
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‎docs/_hardware/16-channel_relay.md‎

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---
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title: 16 Channel I2C Electromagnetic Relay Module IoT
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categories: [Hardware, Relay]
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tags: [relay, i2c, 16channel]
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image:
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path: /assets/img/16 Channel I2C Electromagnetic Relay Module PCF8575.webp
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src: /assets/img/16 Channel I2C Electromagnetic Relay Module PCF8575.webp
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alt: '16 Channel I2C Electromagnetic Relay Module PCF8575 header image'
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device_hardware: GPIO
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device_address:
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'Enter the IO Expender type, the relay number (starting at 1), and then the
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I2C address with optional I2C bus number: `pcf8575-1,0x4c,3`'
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---
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## Information
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The IOT Electronic 16 Channel I2C Solid State Relay Module provides 16 isolated
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channels for Arduino and Raspberry projects, supporting 100-240V AC control.
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This IOT Electronic 16 Channel I2C Solid State Relay Module offers robust
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control for your microcontroller projects. Designed for compatibility with
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Arduino, Raspberry, and other microcontrollers, it provides 16 isolated solid
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state relay channels.
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### Key Features
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- Control 16 independent channels using an I2C interface.
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- Built around the efficient **PCF8575** I2C expander chip.
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- Designed for compatibility with Arduino, Raspberry, and various
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microcontrollers.
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### Device Specifications
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- PCB Board Dimension: 210mm x 72mm
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- Compatibility: DRG-01 DIN rail plastic holder
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- Isolation: Full opto and air isolation from high voltage
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- Operation DC Voltage: 3.3V and 5.0V
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- Maximum Current @5.0V: 450mA
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- AC Controlling Voltage Range: 100…240VAC
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- AC Voltage Frequency Range: 50…60Hz
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- Minimum AC Current per Channel: 30mA
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- Maximum AC Current per Channel: 2A
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- I2C Device Slave Address: Changeable
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- Expandability: Connect up to 8 devices to one I2C bus, controlling up to 128
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channels
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- Indicators: Red LED indicators for each SSR relay channel
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This versatile relay module simplifies projects requiring multiple high-voltage
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switching capabilities. Its I2C interface allows for easy integration and
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expansion, enabling control of up to 128 channels with multiple modules. The
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opto and air isolation ensure safety and reliability when dealing with AC loads
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up to 240V, making the IOT Electronic 16 Channel I2C Solid State Relay Module an
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excellent choice for demanding applications.
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### Ideal for
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- Makers and hobbyists working with Arduino and Raspberry Pi.
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- Automation projects requiring multi-channel AC switching.
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- Industrial control applications needing isolated relay outputs.
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- Projects where space-saving and expandability are crucial.
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- Electronics enthusiasts building custom control systems.
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[16 Channel I2C Electromagnetic Relay Module PCF8575](https://www.tindie.com/products/bugrovs2012/16-channel-i2c-electromagnetic-relay-module-iot/#product-description)
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{% include_relative _relay_detail.md %}

‎docs/_hardware/hd30a-4-channel_relay.md‎

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---
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title: HD30A 4 Channel Electromagnetic I2C Relay 12V 30A
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title: HD30A 4/8 Channel Electromagnetic I2C Relay 12V 30A
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categories: [Hardware, Relay]
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tags: [relay, HD30A]
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tags: [relay, HD30A, 4channel, 8channel]
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image:
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path: /assets/img/HD30A_4_Channel_Electromagnetic_I2C_Relay_12V_30A.webp
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[HD30A 4CH/8CH Channel Electromagnetic relay](https://www.tindie.com/products/bugrovs2012/hd30a-4-channel-electromagnetic-i2c-relay-12v-30a/)
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Other relay boards with a **PCF8574** chip should work.
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[8 Channel I2C Electromagnetic Relay Module](https://www.tindie.com/products/bugrovs2012/8-channel-i2c-electromagnetic-relay-module/)
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{% include_relative _relay_detail.md %}

‎docs/_hardware/io-expander.md‎

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---
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title: IO Expander
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categories: [Hardware, Button, I2C]
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tags: [button, expander, pcf8574]
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tags: [button, expander, pcf8574, pcf8575]
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permalink: /hardware/io-expander/
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image:
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alt: 'PCF8574 IO Expander'
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---
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With the IO expander pcf8574 you can add more GPIO
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With the IO expander pcf8574/5 you can add more GPIO
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[relays](/TerrariumPI/hardware/#relays) and
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[buttons](/TerrariumPI/hardware/#buttons) to TerrariumPI. This IO expander does
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only support on/off actions. So it is not possible to use this IO expander with
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a DHT sensor. You cannot read out the extra GPIO ports.
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## PCF8575 Bug
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At the moment it is **not** possible to use a pcf8575 IO expander to add more
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buttons. Due to a
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[bug in the used library](https://github.com/rp3tya/PCF8575/issues/5), we can
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only support [relays](/TerrariumPI/hardware/#relays) with this IO expander.
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## Addressing
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In order to use this IO expander, enter the following address in the GPIO relay
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or button address field.\
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`pcf8574-<IO expander port>,<I2C Address>,[I2C Bus number]`
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`pcf857[4/5]-<IO expander port>,<I2C Address>,[I2C Bus number]`
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`<IO expander port>` is mandatory and is a number from 1 till max ports.
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`<IO expander port>` is mandatory and is a number from **1** till max ports.
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`<I2C Address>` is mandatory and specified
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[here](/TerrariumPI/hardware/#i2c-bus).

‎docs/_tabs/hardware.md‎

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[pcf857**5**](/TerrariumPI/hardware/io-expander/) to select the used IO
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expander.
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`<IO expander port>` is mandatory and is a number from 0 till max ports - 1.
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`<IO expander port>` is mandatory and is a number from **1** till max ports.
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`<I2C Address>` is mandatory and specified [here](#i2c-bus).
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‎docs/assets/img/16 Channel I2C Electromagnetic Relay Module PCF8575.webp‎

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‎hardware/button/__init__.py‎

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"Create a new button based on type"
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self._device = {"device": None, "id": None, "address": None, "name": None, "state": None}
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self._checker = {"running": False, "thread": None}
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self._inverse = False
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self.id = button_id

‎hardware/io_expander.py‎

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# pip install i2crelay (git)
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from i2crelay import I2CRelayBoard
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# pip install pcf8575
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from pcf8575 import PCF8575
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class terrariumIOExpanderException(TypeError):
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@classproperty
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def available_hardware(__cls__):
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return {"PCF8574": lambda: terrariumPCF8574IOExpander}
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return {"PCF8574": lambda: terrariumPCF8574IOExpander, "PCF8575": lambda: terrariumPCF8575IOExpander}
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# Return polymorph IO expander....
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def __new__(cls, hardware_type, address):
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def _load_device(self, address):
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return I2CRelayBoard(address[1], address[0])
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class terrariumPCF8575IOExpander(terrariumIOExpander):
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HARDWARE = "PCF8575"
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NAME = "PCF8575 Expander (16 ports)"
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# Work around bug: https://github.com/rp3tya/PCF8575/issues/5
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# Alternative in comments https://www.tindie.com/products/bugrovs2012/16-channel-i2c-electromagnetic-relay-module-iot/
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# Keep own internal state
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# Relays starting at number 1 (human counting)
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def __set_relay(self, port, action):
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self.__internal_state[port-1] = action
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self.__device.port = self.__internal_state
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def __get_relay(self, port):
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return self.__internal_state[port-1]
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def _load_device(self, address):
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device = PCF8575(address[1], address[0])
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# Force all relays to off position
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self.__internal_state = 16 * [False]
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device.port = self.__internal_state
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return device
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def switch_on(self, port):
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self.__set_relay(port, True)
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def switch_off(self, port):
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self.__set_relay(port, False)
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def is_on(self, port):
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return self.__get_relay(port) == True
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def is_off(self, port):
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return not self.is_on(port)

‎hardware/relay/gpio_relay.py‎

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device = None
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if address[0].lower().startswith("pcf8574-"):
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device = terrariumIOExpander("PCF8574", ",".join(address[1:]))
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elif address[0].lower().startswith("pcf8575-"):
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device = terrariumIOExpander("PCF8575", ",".join(address[1:]))
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if device is not None:
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device.set_port(int(address[0].split("-")[1]))

‎requirements.txt‎

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# Hardware / sensors packages
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gpiozero==2.0.1
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# Github version is more updated
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# Github versions are more updated
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git+https://github.com/oweidner/i2crelay
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git+https://github.com/rp3tya/PCF8575
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smbus2==0.5.0
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smbus==1.1.post2
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# Github version has some serious patches which we need. Pyipi version is outdated

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