IOX-16 User`s Manual - Unified Microsystems
Contents
1. Unified Microsystems 1OX 16 User s Manual Version 1 00 April 2013 Overview The IOX 16 Arduino compatible shield is an easy way to add 16 additional digital Input Output I O lines to your Arduino system It uses 12C communications for control 12C is a bidirectional serial protocol that only requires two control lines The 12C protocol allows interfacing with a wide variety of devices and multiple units of the same device For example up to 8 IOX 16 boards may be stacked providing a total of 128 additional I O lines Note that I2C is also referred to as a Two Wire Interface TWI The heart of the IOX 16 is a Microchip Technology MCP23017 I O expander IC The MCP23017 has two 8 bit ports A amp B Each port has its own set of registers that must be configured in your program sketch for the desired operation Each bit in the ports can be individually configured as an input or output The pins configured as outputs can be set high or low and the state of the input pins can be read by the Arduino The MCP23017 is a complex IC The examples in Appendix 1 use the simplest modes to be easier to understand and make changes If you need to use the more complex features of the OX 16 it is suggested you study the MCP23017 data sheet available on the Microchip website www microchip com and write your program to match your particular application The IOX 16 has several hardware features to make it as flexible as possible to meet the n2. the A4 and AS signals on the Arduino Uno and Duemilanove Newer version Arduino processor boards may expand the connector with I O pins D8 D13 to 10 pins and put the SDA and SCL signals on the new pins The Uno R3 has SDA and SCL on both the A4 and A5 lines as well as these expansion pins The IOX 16 PCB has support for future use of the alternate source Jumpers J16 and J17 select the source for SDA and SCL These jumpers should be left in the factory default state with the shorting blocks to the sides with the J16 and J17 labels when using Arduino Uno R3 and earlier boards that provide the 12C signals on pins A4 and AS 12C Control Signal Pull Ups The SDA and SCL 12C control lines are open collector types This means they need to have pull up resistors to the source voltage Only one set of pull up resistors should be on the I2C bus Jumpers G1 and G2 are used to connect the 2 2K ohm pull up resistors to the supply voltage Remove G1 and G2 if you have another shield using 12C and it is using its own pull ups If you have multiple OX 16 boards in your project leave G1 and G2 installed on one board and remove them on the others I O Headers The 16 expansion I O lines are available on 10 pin right angle connectors on the edge of the board The bits are segregated into two 8 bit ports Port A and Port B The right angle headers are designed to be used with standard 1 ribbon connectors The pin out of the connectors is shown in the following tabl
3. AARA HAHAHAHAHHA HHHH HHHH HHRHH HAHAHHAHAHA HAHAA HHHH HHAH HHHH HHHH HHHH HHHHHHHHHHHHHHHHHHHH OX 16 Arduino Input Demo program Read the values of the inputs and send the results to the Arduino Serial Monitor This program is a simple example to show how to set up the IOX 16 or other Arduino shield that uses a Microchip MCP23017 I O expander IC It reads Port A and prints the the results in the Serial Monitor The OX 16 must be set up as follows The address is set up to 0 For a simple test Port A data pins can be connected to ground through switches Port A pin Ground Switch Duplicate the above circuit for each Port A pin 0 7 Enter this program and Upload to the Arduino Once upload is completed open the Serial Monitor in the Tools tab If a switch is closed the corresponding pin will show up as a 1 on the Serial Monitor display Revision 1 00 4 20 2013 Gary C Sutcliffe and Unified Microsystems www unifiedmicro com This program is released to the public domain Yf EE EEERT LAE ELEALEALE LARS AE SLE E SEES EL SELES RA EEEE SALLE FEIET KEEFER TETEE EEL SALA REALS SE RELL ERLE SESS ELAS LANALE TESTER ERE EE ES include lt Wire h gt The I2C communications uses the Wire library You might need to download from Arduino cc and put into your library directory const byte IOX_BASE_ADR 0x20 Base Address of MCP23017 Chip with address lines all set to ze
4. ccess These are labeled with the letter A or B and the bit number For example AO is bit O of Port A B3 is Port B bit 3 etc 1 O Connector Spare The right angle I O headers leave one pin available for connection to one of the Arduino signals power or a signal on your custom circuit These go to pin 1 of the right angle headers Pad AX is for Port A and BX is on the Port B connector Interrupt lines The MCP23107 IC has a number of options that allow the IC to generate an interrupt to the host CPU under certain circumstances such as an input pin changing state The interrupt signal lines for Port A and Port B are available at the pads marked IA and IB respectively If you want to use interrupts you will need to wire up one or both of these pins to one of the Arduino pins supporting interrupts Refer to the MCP23017 data sheet for information on configuring the internal registers for generating interrupts Programming Information Since the lOX 16 uses the 12C interface the easiest way to communicate with it is with the standard Arduino Wire library functions If you are not familiar with 12C or the Arduino Wire library more information can be found at http arduino cc en Reference Wire If the Wire library is not already in your library directory down load it from the Arduino site and install it The Microchip MCP23017 is a complex IC To fully utilize its capability refer to the data sheet available from www microchip com However for simpl
5. e Pin Signal Pin Signal 1 AX BX Spare connect as needed 6 Port bit 4 2 Ground 7 Port bit 3 3 Port bit 7 8 Port bit 2 4 Port bit 6 9 Port bit 1 5 Port bit5 10 Port bit O Prototyping Support The IOX 16 has areas to put your own custom circuitry needed for your project in the form of pads in a 1 grid The OX 16 has additional features to make wiring your custom circuits easier There are two areas of the prototype area with white outline boxes near the edges of the circuit board These indicate areas where the Arduino CPU board has connectors that might interfere with your circuit wiring Special care must be used above the USB connector where the metal case may short out your circuitry Use care when placing components in these zones Ground Pads There are two sets of 3 pads in a white box labeled GND You can get access to ground by wiring to any of these pads VDD Pads There are 3 pads in a white box labeled VDD near the center of your board You can access your supply voltage from any of these pads The voltage at these pads will be the same as the voltage selected with J7 Arduino Signal Pads The signals from the Arduino are brought out to pads next to the stacking connectors These pads are labeled for your convenience 1 O Expansion Signal Pads The 16 I O lines are routed to the 10 pin right angle connectors Each signal also has a solder pad if your custom on board circuitry needs a
6. e applications the examples in Appendix 1 will help get you going quickly You can down load these examples from the Support and Download page at www unifiedmicro com Warranty Information The IOX 16 is warranted for 90 days from purchase date Unified Microsystems will at its option repair or replace defective units returned during the warranty period Warranty does not cover damage due to improper setting of the voltage select jumpers or damage caused when adding circuits to the prototype area Unified Microsystems reserves the right to change specifications of it products at any time without notice Schematics sample programs FAQs and additional information can be found at www unifiedmicro com support Support is provided by email only w9xt unifiedmicro com Include IOX 16 in the subject line www unifiedmicro com APPENDIX 1 Example Program Output Demo This program can be entered by hand or can downloaded from the support and down load page at www unifiedmicro com EEE EEE EEE EEE HAHAHHAHAHA HAHHAA ARHAR HHHH H HHHH H HHHH H HHHH HHHHHHHHHHHHH OX 16 Arduino Output Demo program writes test pattern to LEDs on both ports This program is a simple example to show how to set up the IOX 16 or other Arduino shield that uses a Microchip MCP23017 I O expander IC It will turn the LEDs on and off in a set of patterns The LEDs can be connected to either port The OX 16 must be set up as follows The address is set
7. eeds of your application This requires the OX 16 to be configured before use IMPORTANT The IOX 16 voltage jumper must be set before plugging it into your Arduino or Arduino compatible CPU modules Severe damage to the IOX 16 and or Arduino can result from improper configuration Specifications Models 1OX 16 Expander with 8 pin header for use with Duemilanove Uno etc IOX 16 R3 Expander with 10 pin connector for use with Uno R3 and later Arduino models Size 2 75 X 2 1 Maximum external DC supply voltage 15V Internal Supply voltage 3 3V or 5 V selectable Output sink source current maximum Individual pin 25ma_ IC total 125ma Configuration This section covers how to set the jumpers on the IOX 16 prior to use The jumpers must be configured before installing the IOX 16 on your Arduino Voltage Selection Jumper J7 is used to set the operating voltage It is critical that the voltage is set to match the voltage of the Arduino or Arduino compatible CPU Mixed voltages may damage or destroy the Arduino IOX 16 or other shields in the stack You can use the 5V or 3 3V supplied by the Arduino by setting the jumper J7 to 5A 5V from Arduino or 3A 3 3V from Arduino The Arduino on board regulator may not be able to supply enough current if your application draws too much power Also USB supplied power is limited to 500ma If your application requires more current you can supply power through the DC in connector on the Arduino Th
8. en you can use the OX 16 5V on board regulator by setting jumper J7 to the L position Local Regulator L L J7 J7 J7 o 3A 3A 3A 3 O 5A 5A 5A 5V From Arduino 3 3V From Arduino IOX 16 Regulator Address Selection The Arduino communicates to the IOX 16 using the 12C protocol The 12C protocol includes a two part address The first part of the address identifies the type of IC on the bus This allows using ICs with different functions on the 12C bus You could for example have an 12C memory device or a real time clock device in addition to the IOX 16 expander The base address for the OX 16 is hex 0x20 The second part is the unit address It represents the unit number You can have up to 8 IOX 16 boards stacked to get up to 128 additional I O lines Each IOX 16 must have a different address with a value of 0 7 The first OX 16 will normally have the address 0 the second will be address 1 etc The factory default is address 0 The jumpers SO S1 and S2 set the board address Add or remove the shorting blocks per the table below to set each IOX 16 board addresses Unit ADDRESS S2 S1 so Unit ADDRESS S2 S1 so 0 0x20 IN IN IN 4 0x24 OUT IN IN 1 0x21 IN IN OUT 5 0x25 OUT IN OUT 2 0x22 IN OUT IN 6 0x26 OUT OUT IN 3 0x23 IN OUT OUT 7 0x27 OUT OUT OUT 12C Control Signal Source The IOX 16 uses two 12C control lines SCL clock and SDA data These signals are shared with
9. lues on Port A will be displayed in the Serial Monitor byte readData location to store data from Port A Wire beginTransmission IOX_BASE_ADR need to set up the proper register before reading it Wire write GPIOA Even though we are doing a read we first have to write the address of the register the read will be from Wire endTransmission Wire requestFrom IOX_BASE_ADR byte 1 Now we start the actual read while Wire available 0 wait unit the data gets back readData Wire read get the data note bitwise inversion to make it easier to tell what switch is closed Wire endTransmission Serial println readData BIN Print out results on Serial Monitor delay 500 wait 500 miliseconds before checking again end of loop
10. n join i2c bus The port pins can be either inputs or outputs Set both ports to all outputs Wire beginTransmission IOX_BASE_ADR all 12C commands begin with this statement and the address of the chip Wire write byte IODIRA select a write to the IODIRA register Wire write byte 0x00 set all of bank A to outputs O output 1 input Wire write byte 0x00 set all of bank B to outputs If we do multiple writes inside a single 12C command the port address increments Wire endTransmission all 12C commands must end with this statement end of setup void loop Each pass through the loop will incremend idx which is used to index the pattern in the testPat array for byte idx 0 idx lt MAXPAT idx Wire beginTransmission IOX_BASE_ADR All accesses to the expander start with this statement to the chip address Wire write GPIOA address bank A Wire write byte testPat idx value to send Wire endTransmission after sending the pattern to Port A repeat to Port B Wire beginTransmission IOX_BASE_ADR Wire write GPIOB address bank B Wire write byte testPat idx value to send Wire endTransmission delay 300 wait 300 miliseconds before changing to the next pattern endof loop Example Program Input Demo This program can be entered by hand or can downloaded from the support and down load page at www unifiedmicro com HHHH HHHH HHHH HHHH HHHH H
11. ro grounded Address for second MCP23017 would be 0x21 the next 0x22 etc MCP23017 internal registers Not all registers included See the Microchip MCP23017 datasheet for full list const byte IODIRA 0x00 Port A direction register Write a O to make a pin an output a 1 to make it an input const byte GPIOA 0x12 Register Address of Port A read data from or write output data to this port const byte GPPUA 0x0c Register to enable the internal pull up resistors on Port A 1 pull up enabled void setup Serial begin 9600 configure the serial port so we can use the Serial Monitor Wire begin join i2c bus The port pins can be either inputs or outputs Set Port A pins as all inputs Wire beginTransmission IOX_BASE_ADR all I2C commands begin with this statement and the address of the chip Wire write byte IODIRA select a write to the IODIRA register Wire write byte Oxff set all of bank A to inputs 0 output 1 input Wire endTransmission all 12C commands must end with this statement This sets the pull ups on the port Don t do this if port is actively driven or circuit has external pull ups Wire beginTransmission IOX_BASE_ADR Wire write byte GPPUA Select port A pull up register Wire write byte Oxff turn all the pull ups on 1 ON O OFF Wire endTransmission end of setup void loop Port A will be read each pass through the loop and the va
12. up to 0 The output pins are connected to LEDs with appropriate current limit resistors Port pin gt Ground 330 ohm resistor LED Duplicate the above circuit for each Port pin 0 7 Revision 1 00 4 19 2013 Gary C Sutcliffe and Unified Microsystems www unifiedmicro com This program is released to the public domain LL ERSESEL NALA EE LS EEE EEL EREL ELE ELENA ENEE ESE E LLL ERE SELLA RELL AAS ELLE EAE LEAL EE LEELA NEES LL ELEL ELSE LALA ELE LES ES TEEPEE EEEE KEETE include lt Wire h gt The I2C communications uses the Wire library const byte IOX_BASE_ADR 0x20 Base Address of MCP23017 Chip with address lines all set to zero grounded Address for second MCP23017 would be 0x21 the next 0x22 etc MCP23017 internal registers Not all registers included See the Microchip MCP23017 datasheet for full list const byte IODIRA 0x00 Port A direction register Write a O to make a pin an output a 1 to make it an input const byte IODIRB 0x01 Port B direction register const byte GPIOA 0x12 Register Address of Port A const byte GPIOB 0x13 Register Address of Port B define MAXPAT 15 Number of LED test patterns the testPat array holds the patterns to output to turn the LEDs on and off A 1 will turn the LED on const byte testPat Oxff 0x00 0xaa 0x55 0x00 0x01 0x02 0x04 0x08 0x10 0x20 0x40 0x80 0x00 0xOf void setup Wire begi
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