IO Expander Shield. User Guide. Rev 9

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1 IO Expander Shield User Guide Rev

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3 IO Expander Shield User Guide Introduction Numato Lab's IO Expander Shield extends Arduino's digital and analog I/O pins and makes Arduino suitable for high pin count applications. This shield suitable for applications that needs to control more number of input and output devices (sensors, LEDs etc..). This shield will add additional I/O pins to your Arduino. of these pins are digital I/Os controlled via IC bus by using two IC pins on Arduino (A and A) and rest pins can be used as analog inputs, which uses only one analog pin(a) of Arduino. Overall plugging this shield on to Arduino will give pins to work with (including existing Arduino's I/Os). Some of the possible uses of this shield include Robotics Lighting Control Sensor and switches interfacing Keyboard interfacing General purpose I/O functionality DIY and Hobby Features Adds digital I/O and Analog Input pins by using just Arduino pins. Two Microchip MCP ICs for digital I/O expansion One NXP HC Analog Multiplexer/Demultiplexer IC for Analog expansion Jumpers provided for IC Address selection for MCP ICs Arduino Uno, Arduino Mega compatible Small size, Low cost and Light weight IO Expander shield consists of two bit MCP GPIO Expander ICs(U & U) and one NXP HC Analog Multiplexer. The digital I/O pins from MCP(U) are available on header and digital I/O pins from MCP(U) are available on header. These headers include V, and Interrupt pins for convenience. More details on Digital I/O pins is available else where in this document. HC is a channel Analog Multiplexer/Demultiplexer with four selection inputs(s, S, S, S) connected to the MCP(U) IC PORTA pins(pa, PA, PA, PA), independent inputs/outputs(y to Y) are available on a header along with two V and two pins. This shield is powered from Arduino Vin pin, an on board voltage regulator is provided on the shield to derive V operating power supply. A power on LED indicates when the shield is powered up. NUMATO SYSTEMS PVT LTD

4 IO Expander Shield User Guide How to Use the Shield The following section describes how to use this shield. Components / Tools Required Along with this shield, you may need the following items for easy and fast installation.. Arduino Uno / Arduino Mega or a Compatible board. -V External DC power supply to power Arduino. USB A to B cable to connect Arduino to host PC. Connection Diagram Address Pins MCP IC slave interface can have up to unique bus addresses, that means chips can communicate over a single IC bus at a time. IO Expander shield uses two MCP ICs (U and U) NUMATO SYSTEMS PVT LTD

5 IO Expander Shield User Guide each supports bit addressing with four fixed upper bits() and three user defined hardware address bits(a, A, A). Jumpers are used to set the user definable part of the device address. There are six selection jumpers available on the board for these hardware address bits. AD, AD and AD for MCP(U), and AD, AD and AD for MCP(U) thus allowing user to set the address of each IC by connecting the address pin to () or (). The shield is shipped with address for U and for U. One can use shields over single IC bus ie shields can be controlled with single Arduino board by properly selecting address for each chip. Stacking the multiple shields this way can yield up to I/O pins. Table below summarizes the Address pins connection in detail. I/O Ports Selection Jumper Pin connection with MCP Default jumper position on shield AD A of MCP(U) () AD A of MCP(U) () AD A of MCP(U) () AD A of MCP(U) () AD A of MCP(U) () AD A of MCP(U) () There are total digital I/O and analog pins available on three separate headers on the shield. The digital pins are numbered from to in which to are controlled by MCP(U) and to are controlled by MCP(U) through IC bus. Each pin can individually be controlled by accessing the specific port register. Please refer to MCP data-sheet for register addresses and more details. The Analog pins are numbered from to. These pins are connected to analog multiplexer IC HC. The selection inputs(s, S, S, S) of this IC are connected to the PORTA pins(pa, PA, PA, PA) of MCP(U), hence the pin selection for HC IC can be done by writing the address input( ) to PORTA register of MCP(U). The Z terminal (common terminal) of HC is wired to Arduino's Analog pin(a). Reading Arduino's A pin will read the analog voltage on HC's analog pin that is selected by the selection inputs(s, S, S, S). Each header has V and connections available for convenience. Table below summarizes the description of each pin on the header. NUMATO SYSTEMS PVT LTD

6 IO Expander Shield User Guide Digital I/Os Pin out connections of MCP (U) Pin name on the Digital Header Description Pin out connections of MCP (U) Pin name on the Digital Header Description INT Interrupt output for PORTB INT Interrupt output for PORTB INT Interrupt output for PORTA INT Interrupt output for PORTA I/O pins of PORTB(GPB-) I/O pins of PORTB(GPB-) I/O pins of PORTA(GPA-) I/O pins of PORTA(GPA-) Ground Connection Ground Connection V Connection V Connection Analog Inputs Pin name on the Analog Header Pin connection with HC Description Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In Y Analog In NUMATO SYSTEMS PVT LTD

7 IO Expander Shield User Guide Power Supply The power supply for this shield is derived from Vin/DC Jack of the Arduino board, connect a -V of DC supply to the external power supply pin (DC Jack) of Arduino. This power supply voltage is regulated using an onboard voltage regulator. The power on LED indicates the power supply status. Additional Information Selection Jumper(GS) This on board jumper pin is used to connect the Enable input pin of HC IC to. When this Enable input pin is LOW one of the sixteen Analog pins of HC IC is selected(on state). All unselected pins will be in OFF state. When this pin is HIGH, it makes all pins to OFF state. (This shield is shipped with Enable Input connected to ). Common Input/Output Common Input/Output (Z)pin of HC IC, is connected to Arduino's Analog pin A. This common I/O is internally routed to one of the I/Os (Y Y) on the chip based on the configuration of selection inputs. Interrupt Pins The Interrupt pins of MCP are brought out as standard header pins in which INT, INT are associated with PORTA and INT, INT are associated with PORTB of corresponding chips. The chip generates an interrupt if a mismatch condition exists between the current port value and the previous port value. This could be very useful for detecting changes quickly without having to poll all the I/O over IC frequently. Please see MCP data-sheet for more details on using interrupts. NUMATO SYSTEMS PVT LTD

8 IO Expander Shield User Guide Connecting the shield to Arduino Uno. Mount IO Expander Shield on Arduino Uno (or compatible) board.. Connect -V DC power supply to the Arduino's external DC jack/vin.. Download Arduino IO Expander Demo code from.. Open the code in Arduino IDE, compile and upload to the board. The following three sample sketches are available.. DigitalOut.ino Generates square wave on all Digital pins. DigitalIn.ino Prints the logic state on digital input pins if at least one input is high. AnalogIn.ino Displays reading equivalent to the analog voltage on analog input pin. Test the port outputs using LEDs or a multimeter.. Test the port inputs using potentiometers (for analog input) or other input devices.. Open serial monitor to check the input readings. NUMATO SYSTEMS PVT LTD

9 IO Expander Shield User Guide Technical Specifications Parameter * Value Unit Basic Specifications Number of Expanded Digital I/Os Number of Expanded Analog I/Os Digital circuit power supply voltage - V Maximum current drawn by shield ma MCP Specifications Supply Voltage().-. V GPIO Input Low Voltage(VIL) VSS-. V GPIO Input High Voltage(VIH).- V GPIO Output Low Voltage(VOL). V GPIO Output High Voltage(VOH) -. V Maximum Output Current sunk/source by any output pin ma HC Specifications Supply Voltage(VCC) - V Supply Current(ICC) ma Input Voltage -VCC V Output Voltage VCC V * All parameters considered nominal. Numato Systems Pvt Ltd reserve the right to modify products without notice. NUMATO SYSTEMS PVT LTD

10 IO Expander Shield User Guide FAQ Q. Where do I find Demo code for this product? A. Visit and navigate to the product page to download Demo code. Q. I need a customized version of this product, can Numato do the customization for me? A. Yes, we can definitely do customization but there may be minimum order requirements depending on the level of customization required. Please write to sales@numato.com for a quote. Q. Where can I buy this product? A. All Numato products can be ordered directly from our web store We accept major credit cards and Paypal and ship to almost all countries with a few exceptions. We do have distributors in many countries where you can place your order as well. Please find the current list of distributors at NUMATO SYSTEMS PVT LTD

11 IO Expander Shield User Guide Physical Dimensions Schematics See next page NUMATO SYSTEMS PVT LTD

12 A A B B C C Date: jun KiCad E.D.A. Rev: Size: A Id: / Title: IO expander File: IOexpaander.sch Sheet: / Numato Lab License : CC BY-SA GS GS RESET V V VIN A A A A A/SDA/IC A/SCL/IC /PWM RX /PWM/SS TX /PWM/MOSI/SPI /MISO/SPI /PWM /SCK/SPI /PWM AREF /PWM U AURD_COMM_SHIELD AD AD AD AD AD AD PWR LED V V ANALOG DIGITAL INT V INT INT V INT PWR_FLAG C UF VIN VIN C.UF C UF VI VO U GS GS GS GS GS GS GS GS GS GS GS GS INTB INTA INTB INTA INTB INTA INTB INTA R K P CONN_X D LED C.UF P CONN_X P CONN_X R K R K C.UF C.UF Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y PB PB PB PB PB PB PB PB PA PA PA PA A A A A A A A A B B B B B B B B PA PA Y Y Y Y Y Y Y Y PA PA Y Y Y Y Y Y Y Y Z Z PA PA PA PA PA PA PA PA PB PB PB PB PB PB PB PB A A A A A A A A B B B B B B B B GPB GPB GPB GPB GPB GPB GPB GPB VSS INTA NC GPA SCL GPA SDA GPA NC GPA A GPA A GPA A GPA RESET GPA INTB U MCP GPB GPB GPB GPB GPB GPB GPB GPB VSS INTA NC GPA SCL GPA SDA GPA NC GPA A GPA A GPA A GPA RESET GPA INTB U MCP R K R K Z Y Y Y Y Y Y Y Y S Y S Y Y S Y S VCC E Y Y Y Y U HC