Embedded Dreams

ED1021 - I/O Expander with UART interface
ED1021 is an I/O expander fully controlled and configured through an UART interface. I/O expanders expand the number of pins available to a host system (typically, a microprocessor). This product includes a low profile 4.000 MHz crystal and pair of 22pF capacitors to easily put you up running.

Highlights

• 4.5V to 5.5V power supply.
• 12 GPIOs.
• Up to 40mA maximum current in each output except GPIO8 (up to a total device current of 175mA).
• Most GPIOs can be an input to a 10bit ADC.
• Simple interface to most PC serial ports.
• Uses a common 4.000 MHz crystal.
• Easy to use UART interface at 38400 bps.
• One of a set of 4 GPIO pins can be used as an interrupt request (IRQ) pin.
• High stability internal ADC voltage reference for precise readings.

Description
Each pin can be configured either as an input, input with pull-up, input to an internal 8 or 10-bit ADC (10 of the 12 GPIOs), push-pull output or disconnected. When a change happens in a GPIO configured as digital input, ED1021 can automatically send a notification to the host system through the UART interface or an IRQ line. The IRQ line can be configured to be any of the GPIO8-11 pins.

Example Application
Below is an example application in which a PC controls 2 LEDs, reads 4 pushbuttons and 3 slow changing analog signals and monitors a V+ voltage (to display a battery charge state).


Connection to the PC uses the COMx port. Most PC serial ports and USB-to-Serial converters will tolerate the lower voltage levels provided by ED1021. Some USB-to-Serial converters even use 5V TTL signals, which make them just perfect for interfacing with this I/O expander. The circuit must be powered up before connecting the serial port cable to the PC. (click the schematics for a bigger view)

Resources
Datasheet: Download
Windows PC graphical demo application: Download
You can use this application to control an ED1021 connected to a PC through a serial COM port. No installation nor administration rights needed.

Price: 4.00 €

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