Difference between revisions of "Example egpc"
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If a mask is specified then it sets each bit's corresponding pin output latch to high/low accordingly.<br /> | If a mask is specified then it sets each bit's corresponding pin output latch to high/low accordingly.<br /> | ||
If a mask is not specified then the current pin state is retrieved.<br /> | If a mask is not specified then the current pin state is retrieved.<br /> | ||
| − | For example, this writes all pin ouput latches on | + | For example, this writes all pin ouput latches on PortC to high. |
| − | ./egpc /dev/ | + | ./egpc /dev/portc d 0xff |
| − | ...and this reads the current pin data state of | + | ...and this reads the current pin data state of PortC |
| − | ./egps /dev/ | + | ./egps /dev/portc d |
| + | |||
| + | '''Note''' The pin values for Port C are displayed on the board's strip of 8 LEDs. Observe that the LEDs change state when we write to Port C. This only works for Port C, however. Ports A and B must be read with an oscilloscope or multimeter. | ||
===Usage Example. Writing to Port C=== | ===Usage Example. Writing to Port C=== | ||
Revision as of 14:07, 27 December 2013
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.
stub
2. Open the project files.
stub
3. Build the project.
stub
4. Upload the executables to the target system.
stub
Usage and Behavior
egpc reads/writes/configures the GPIO ports.
Hardware Requirements
The egpc C example project will run on any EMAC carrier board.
VERIFY THIS
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].
Usage Example. Port Configuration
./egpc device c (mask)
If a mask is specified it configures the pins for input/output.
If no mask is specified it returns the current configuration.
mask is an input/output bitmask. 1=output and 0=input.
For example, this sets every other pin on PortA to be an output.
./egpc /dev/porta c 0xaa
...and this reads the current pin configuration state of PortA.
./egpc /dev/porta c 0xaa
Usage Example. Port Data
./egpc device d (mask)
If a mask is specified then it sets each bit's corresponding pin output latch to high/low accordingly.
If a mask is not specified then the current pin state is retrieved.
For example, this writes all pin ouput latches on PortC to high.
./egpc /dev/portc d 0xff
...and this reads the current pin data state of PortC
./egps /dev/portc d
Note The pin values for Port C are displayed on the board's strip of 8 LEDs. Observe that the LEDs change state when we write to Port C. This only works for Port C, however. Ports A and B must be read with an oscilloscope or multimeter.
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
