Example egpc
This is a guide to the egpc C example project included in the EMAC OE SDK.
egpc is an application for reading/writing/configuring gpio character devices. Specifically, we read/write/configure the 3 ports (ports A, B and C) on the GPIO header.
The egpc project builds one executable: egpc.
Contents
Opening, Building and Uploading the Project Files
1. Open the C/C++ editing perspective.
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2. Open the project files.
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3. Build the project.
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4. Upload the executables to the target system.
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Usage and Behavior
egpc reads/writes/configures the GPIO ports.
Hardware Requirements
The egpc C example project will run on any EMAC carrier board.
Using egpc
./egpc device d/c/i (mask)
device is /dev/porta, /dev/portb or /dev/portc
d/c/i specifies the port command : d(data), c(configure) or i(index)
mask is a bitmask in hex format in range [0x0,0xff].
Our three commands work like this:
c (mask) Configures the pins for input/output if a mask is specified. Returns the current configuration if no mask is specified. mask is input/output bitmask 1 = output 0 = input ex:
./egpc /dev/porta c 0xaa
sets every other pin on PortA to be an output.
./egpc /dev/porta c
reads the current pin configuration state of PortA.
Usage Example. Writing to Port C
We write a data bitmask to Port C. The values are rendered in our LED strip. (note that only PortC is displayed in the LED strip. Ports A or B would require kind of device to read them; a multimeter or oscilloscope or something like that.)
./egpc /dev/portc d 0x55
LEDs 1-8 are lit: 10101010
MIKE I was thinking that maybe we could have some kind of general purpose "know your board" images (I have created a few) or wiki pages. They would point out things like the GPIO header and the LED strip.
./egpc /dev/portc d 0xaa
LEDs 1-8 are lit: 01010101
