DART-SD410 Android Examples

DART-SD410 - Using Peripherals

This WIKI describes how to use some simple peripheral devices available on VAR-DT410CustomBoard.

Using User LED1

User LED1 (D6) connected to GPIO21 of the CPU. The LED1 is defined in the apq8016-var-dt410.dtsi file under gpio-leds section.

general1 {
	gpios = <&msm_gpio 21 0>;
	label = "led1";
	linux,default-trigger = "none";
	default-state = "off";
	retain-state-suspended;
};

You can access the LED device via serial console by:

$ su 
# cd /sys/class/leds/led1
# echo 1 > brightness
Writing any value other then 0 will turn the led on
# echo 0 > brightness
The led will turn off

You can view available triggers by typing:

# cat trigger
The output will be:
[none] boot-indication usb-online mmc0 mmc1 battery-charging-or-full battery-charging battery-full battery-charging-blink-full-solid wlan-indication-led

Set the trigger to mmc0 device by typing:

# echo mmc0 > trigger

Test it by reading mmc0 device:

# dd if=/dev/block/mmcblk0 of=/dev/null bs=128 count=1000000

Using GPIO

User LED2 (D9) connected to GPIO120 of the CPU. The LED1 is not defined in the apq8016-var-dt410.dtsi file under gpio-leds section.
This allow user acces to this LED as GPIO device. To change the state of the LED via serial console type:

$ su
# cd /sys/class/gpio
# echo 1022 > export
This line creates a new directory gpio1022
The number 1022 calculated as 120 + 902. 120 is the GPIO number, 902 is static offset for CPU gpio.
So changing any other GPIO will lead to 902 + GPIO number.
# cd gpio1022
# echo out > direction
# echo 1 > value
The led will turn on
#echo 0 > value
The led will turn off

To read the current state type:

# cat value
The output will be 0

You can change active state to active low.

# echo 1 > active_low
# echo 0 > value
The led is active low, writing 0 will turn on the led.
# echo 1 > value
The led is active low, writing 1 will turn off the led.

To see all allocated GPIOs in the system type:

# cat /sys/kernel/debug/gpio
The output will be:
GPIOs 577-608, platform/qcom,smp2pgpio-ssr-smp2p-4-out.19, master-kernel:
GPIOs 609-640, platform/qcom,smp2pgpio-ssr-smp2p-4-in.18, slave-kernel:
GPIOs 641-672, platform/qcom,smp2pgpio-ssr-smp2p-1-out.13, master-kernel:
GPIOs 673-704, platform/qcom,smp2pgpio-ssr-smp2p-1-in.12, slave-kernel:
GPIOs 705-736, platform/qcom,smp2pgpio-smp2p-4-out.16, smp2p:
GPIOs 737-768, platform/qcom,smp2pgpio-smp2p-4-in.14, smp2p:
GPIOs 769-800, platform/qcom,smp2pgpio-smp2p-1-out.10, smp2p:
GPIOs 801-832, platform/qcom,smp2pgpio-smp2p-1-in.8, smp2p:
GPIOs 833-864, platform/qcom,smp2pgpio-smp2p-7-out.6, smp2p:
GPIOs 865-896, platform/qcom,smp2pgpio-smp2p-7-in.4, smp2p:
GPIOs 897-900, spmi/qpnp-pin-ffffffc0319b4c00, pm8916-gpio:
 gpio-899 (qcom,hub-reset-gpio ) out hi
 gpio-900 (qcom,sw-sel-gpio    ) in  lo
GPIOs 901-901, spmi/qpnp-pin-ffffffc0319b4800, pm8916-mpp:
GPIOs 902-1023, platform/1000000.pinctrl, msm_tlmm_gpio:
 gpio-914 (ft5x06_reset_gpio   ) out hi
 gpio-915 (ft5x06_irq_gpio     ) in  hi
 gpio-922 (adv7533_hpd_irq_gpio) in  lo
 gpio-923 (led1                ) out lo
 gpio-933 (adv7533_irq_gpio    ) in  hi
 gpio-934 (disp_rst_n          ) in  hi
 gpio-940 (7864900.sdhci cd    ) in  lo
 gpio-1009 (volume_up           ) in  hi
 gpio-1010 (home                ) in  hi
 gpio-1011 (back                ) in  hi
 gpio-1022 (sysfs               ) out lo
 gpio-1023 (USB_ID_GPIO         ) in  hi

From this table you can see that offsets are:

• CPU gpio is 902
• PMIC gpio is 897
• PMIC mpp is 901

Using RTC

There are two RTC devices defined in the system. One is inside DART-SD410 PMIC chip and the second is on VART-DT410CustomBoard.
The main RTC device is DS1307 that is assembled on VART-DT410CustomBoard. It can be accessed via console in the following manner:

$ su
# cd /sys/class/rtc/rtc0
# cat date
Output similar to 2000-01-01
# cat time
Output similar to 00:00:36

To set the timezone use:

# setprop persist.sys.timezone "America/Chicago"

To set the time and date use:

# date -s 20160119.122100
The format is YYYYMMDD.HHmmss

To read back from the RTC0 device use:

# cat date
Output is 2016-01-19
# cat time
Output is 18:21:04
Pay attention that RTC stores time without timezone offset

You can use CR1225 lithium cell to run the RTC clock, insert it into battery holder JBT1.
Set the time and remove the power.
Wait for 5 minutes, plug the power in and verify RTC is still running.

Capturing Screen snapshot

To save the screen contents to a file use:

$ su
# screencap -p /sdcard/screen.png
The file screen.png is created in the /sdcard folder