Revision as of 18:08, 14 September 2012

TODO:

Update peripheral tutorials, finish gpio example program

Categorize new tutorials

Finish tutorials below

How to manage the kernel modules on Linux

How do I edit my kernel command line

Basic Software instructions

igep.ini parameters

The kernel command line syntax is name=value1. These next parameters are supported in igep.ini since IGEP-X_Loader 2.4.0-2:

[kernel]

[kparams]

How to use GPIOs (update it)

Overview

This How-To is meant to be a starting point for people to learn use GPIOs for IGEP devices as quickly and easily as possible. For this how-to i used IGEP firmware Yocto

There are more ways to use GPIOs in IGEP v2, but this one is very simple.

Feedback and Contributing

At any point, if you see a mistake you can contribute to this How-To.

Install binaries via IGEP

Testing driver

To make sure than driver works well, make the next test. I used GPIO_136(sdmmc2_dat4) and GPIO_137(sdmmc2_dat5) because IGEP v2 RC5(without WIFI) don't use them by default:

NOTE: For more information visit this page (under construction).

Configure Mux

Go to:/sys/kernel/debug/omap_mux, and change this mux configuration:

echo 0x104>sdmmc2_dat4
echo 0x104>sdmmc2_dat5

Use cat command to check it:

cat sdmmc2_dat4
cat sdmmc2_dat5

The result will be similar at that:

root@localhost:/sys/kernel/debug/omap_mux# cat sdmmc2_dat4
name: sdmmc2_dat4.gpio_136 (0x48002164/0x134 = 0x0104), b ae4, t NA
mode: OMAP_PIN_INPUT | OMAP_MUX_MODE4
signals: sdmmc2_dat4 | sdmmc2_dir_dat0 | NA | sdmmc3_dat0 | gpio_136 | NA | NA | safe_mode

and

root@localhost:/sys/kernel/debug/omap_mux# cat sdmmc2_dat5
name: sdmmc2_dat5.gpio_137 (0x48002166/0x136 = 0x0104), b ah3, t NA
mode: OMAP_PIN_INPUT | OMAP_MUX_MODE4
signals: sdmmc2_dat5 | sdmmc2_dir_dat1 | cam_global_reset | sdmmc3_dat1 | gpio_137 | hsusb3_tll_stp | mm3_rxdp | safe_mode

Note: OMAP_PIN_INPUT=Input/Output pin and OMAP_PIN_OUTPUT=Output pin, for Read/Write test you need the first one. GPIO is configured in mode 4.

Read/Write test

Link GPIO_136 and GPIO_137 with a wire, these pins are located in J990 connector with numbers 7 and 9. I use the next connector to join them:

Now type next code:

root@localhost:~/gpio-driver/app# ./gpio input 136
root@localhost:~/gpio-driver/app# ./gpio output 137 0
root@localhost:~/gpio-driver/app# ./gpio get 136     
0
root@localhost:~/gpio-driver/app# ./gpio output 137 1
root@localhost:~/gpio-driver/app# ./gpio get 136     
1
root@localhost:~/gpio-driver/app# 

The results (CMOS Voltages: 0V-1V8):

The code above shows that driver works properly, GPIO_136 is configured like input and GPIO_137 is configured like output with value 0, when read GPIO_136 the result is 0. To make sure that works well, configure GPIO_137 with value 1, now GPIO_136 reads 1.
This driver have more options like IRQ, but is not explained here.