#123 Looking at some common IO expanders
What to do when you are using n 8-pin MCU to to the job of a 16pin ore even a 20pin MCU? Well it depends.. but if all you are doing is using IO’s to switch for example relays or similar tasks where the amount of IO’s is important, and not the capabilities of the IOs then you may be able so save costs by purchasing an IO expander instead of an abundantly pin gifted MCU.
These come in all shapes and package sizes and don’t increase the project size too much. Also I tend to use I2C much more then SPI but IO expanders can support both these packages.
Examples like the PCF8574, MCP23017, 74LVC595 and the MCP23S17 which uses SPI if you want to use that instead. The expanders support interrupts but always double check the datasheet before purchasing!
Something similar but not an expander more of a multiplexer IC is the MC14051B Analog Multiplexer/Demultiplexer this is quite common and affordable at least in South Africa and allows analogue pins to be expanded instead of digital.
Some Links to shops in South Africa that sell these expanders:
PCF8574
MCP23017
74LVC595
- not common in South Africa
MCP23S17