Component: IO Expander (PCF8574) (PCF8574) (General Input): Difference between revisions

Latest revision as of 14:37, 13 July 2026

Author	Matrix TSL
Version	1.0
Category	General Input

IO Expander (PCF8574) component

Provides 8 digital input/output pins arranged into an 8-bit port using a I2C bus connection. Up to eight expanders can be connected to the same I2C peripheral by means of three address pins. Supports the PCF8574 and PCF8574A devices allowing up to 16 expanders to be connected to the same I2C bus ( 8 x PCF8574 + 8 x PCF8574A ).

Component Source Code

Please click here to download the component source project: FC_Comp_Source_IOEXP_PCF8574.fcfx

Please click here to view the component source code (Beta): FC_Comp_Source_IOEXP_PCF8574.fcfx

Detailed description

No detailed description exists yet for this component

Examples

No additional examples

Macro reference

Initialise

	Initialise

- VOID	Return

ReadPort

	ReadPort
Reads the value of the IO pins.
- BYTE	Return

WritePort

	WritePort
Writes a value to the IO pins.
- BYTE	Value
Value to write. Range 0-255
- VOID	Return

Property reference

	Properties
	I²C Communications
	Device Type

	External Address
Selects the value of the three address pins for the MCP23S17.
	Channel
Channel selection
	Stop Delay
On older microcontroller devices there is a potential for the I2C hardware channel to lock up if there is not a 10ms delay between an I2C stop event and the next I2C start event. Most modern microcontrollers will not have a problem so this property can be disabled to speed up the I2C communications.
	Baud Select
Baud rate option selector
	Baud Rate
Baud rate to be used
	SDA
Pin used for SDA (data signal)
	SCL
Pin used for SCL (clock signal)
	Simulation
	Label

	Scope Traces
Selects if the scope traces are automatically generated or not
	Console Data
Selects if the console data is automatically generated or not
	API

@@ Line 146: / Line 146: @@
 |-
 |-
-| width="10%" align="center" style="background-color:#EAE1EA;" | [[File:Fc9-conn-icon.png]]
+| width="10%" align="center" class="mtx-class-propfolder" | [[File:Fc9-conn-icon.png]]
-| width="90%" style="background-color:#EAE1EA; color:#4B008D;" | I²C Communications
+| width="90%" class="mtx-class-propfolder" | I²C Communications
 |-
 |-
@@ Line 190: / Line 190: @@
 | colspan="2" | Pin used for SCL (clock signal)&nbsp;
 |-
-| width="10%" align="center" style="background-color:#EAE1EA;" | [[File:Fc9-conn-icon.png]]
+| width="10%" align="center" class="mtx-class-propfolder" | [[File:Fc9-conn-icon.png]]
-| width="90%" style="background-color:#EAE1EA; color:#4B008D;" | Simulation
+| width="90%" class="mtx-class-propfolder" | Simulation
 |-
 |-

SteveT (talk | contribs)