Robostix i2c-io

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Many people have requested the ability to read the robostix ADC lines and GPIO lines from the gumstix. i2c-io allows this to happen.

i2c-io consists of two parts, i2c-io.hex which is installed on the robostix, and the i2c-io program which runs on the gumstix. There are two precompiled versions of i2c-io available:


Contents

Installing i2c-io on the robostix

You need to install the i2c BootLoader first. Then execute this command: 

i2c-load --reset 0x0b write i2c-io.hex

This will download the i2c-io-hex file to the robostix. When the i2c-io program is running, the red LED will flash twice quickly, followed by a longer pause. This sequence will repeat about once per second.

Using i2c-io

The i2c-io program has the following online help: 

Usage: i2c-io [options] i2c-addr cmd [cmd-options]
Manipulate robostix I/O pins

The following commands are supported: 

Info Retrieves information about the robostix program
Get port.pin Retrieves the value of a pin
Set port.pin val Sets the value of a pin
SetDir port.pin dir Sets the direction of a pin
ReadReg regIdx Reads an 8 bit register
WriteReg regIdx val Writes a value into an 8 bit register
 
port.pin specifies a port using a letter (A-G) and a pin (0-7)
For example, C.3 means Port C pin 3
The port may also be specified using the special port ADC
 
The following arguments may be used to modify the behaviour
--hex (or -x) Print ReadReg results in hex
--decimal (or -d) Print ReadReg results in decimal
--version Print the version information for this program
--verbose Print additional information
--help Prints this information


i2c-io i2c-addr Info

The Info command prints some version information about the robostix portion of the i2c-io program: 

# i2c-io 0x0b info
version: 1
minVersion: 1
SVN Revision: 793


i2c-io i2c-addr Get port.pin

Retrieves the value detected on the indicated port and pin. The port can be the letters from A thru G, or ADC. For ports A thru G, the pin can have the range 0 thru 7. For the ADC port, the pin can have the values 0 thru 31. 0 thru 7 correspond to reading pins AD0 thru AD7 in single ended modes. For values 8 thru 31, refer to the ATMega128 datasheet.

One thing to be careful about, on the robostix there are pin numbers in the range 1 thru 8 on the top side of the board. These will be off by one. If you look on the back side of the board, you'll see PC0 thru PC7 and AD0 thru AD7. The numbers here are the pin number being referred to.

When reading an ADC port, the 10-bit value (in the range 0 thru 1023) is printed. For other ports only the value 0 or 1 is printed.


i2c-io i2c-addr Set port.pin value

Sets the value output on a port. If the pin is configured as an output pin, then this will cause the pin to drive at 0v (for an output of 0) or 5v (for an output of 1). If the pin is configured as an input pin, the setting the pin to 1 enables a pullup resistor, and setting the pin to 0 disables the pullup resistor.

'value' can also be the strings on or off (on=1, off=0). Only ports A thru G are valid.


i2c-io i2c-addr SetDir port.pin dir

Sets the direction of the indicated GPIO pin. 'dir' may be 0 or 1, or in or out (in=0, out=1).


i2c-io i2c-addr GetDir port.pin

Returns the direction of the indicated pin


i2c-io i2c-addr ReadReg register

Reads a value from a 'register' on the robostix. The registers can be specified using a symbolc name (i.e. portf) or a number.


i2c-io i2c-addr WriteReg register value

Writes a value into a 'register' on the robostix. The registers can be specified using a symbolc name (i.e. portf) or a number.


Examples

This will turn the Blue LED on: 

i2c-io 0x0b setdir g.3 out
i2c-io 0x0b set g.3 0


And this will turn the Blue LED off: 

i2c-io 0x0b set g.3 1


This will also turn the Blue LED on using the writereg command: 

i2c-io 0x0b writereg ddrg 0x18
i2c-io 0x0b writereg portg 0


And this will turn the Blue LED off: 

i2c-io 0x0b writereg portg 0x08


Source code

The source code for the i2c-io is available from SVN, You'll also need the robostix/Common and robostix/Shared directories to build the robostix side of i2c-io, and the robostix/gumstix/Common and robostix/gumstix/i2c-io directories to build the gumstix side of things.

API

There is a C library available for i2c-io called i2c-io-api.

Troubleshooting

There are some steps for testing the i2c hardware connection on the Robostix i2c test page.

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