#Kernel module for dothat (Display O Tron Hat) This driver is still experimental. Use it at your own risk. He can not be load with kernel tree for the moment.
##Why a kernel module? The first things when I bought one is try to play with. The installation install lots of thing and it's really a pain to test it. Why just plug it and play it just on line in bash? The only language available is python. I love python but i don't want to be limited in one language. I'll really want to control it with C / bash / etc.. and share with several processus. The python lib by piromoni not work very well with touch. First i think it's a hardware problem but you can check that the touch work very well with this driver.
##The hardware:
The display o tron hat is not just on components but three components togother:
- A sn3218: used to backlight the LCD. Its a 6 segments BGR color.
- A cap1166: used to handle touch and control the 6 graph leds.
- A st7036: The LCD components to draw.
This 3 components not use the same protocol. The sn3218 and cap1166 use I2C and the st7036 use SPI. The st7036 is also controlled by a GPIO PIN to selected a dedicated register.
##Requirements: You need the source of your kernel and the spidev need to be disable. The spidev is not compile in module with all kernel provide by Hexxeh with rpi-update. Thanks to the Kernel-tree we are not need to recompiled the kernel. Just copy the nospidev.dtbo in your /boot/overlays and add this line in /boot/config.txt:
dtoverlay=nospidev
##How to compile: You can update with the rpi-update
sudo rpi-update
Install or update your source kernel by the method provide here: https://github.com/notro/rpi-source/wiki
Then
git clone https://github.com/realPy/dothat-module.git
cd dothat-module
make
insmod dothat.ko
Compile the client: Replace the "tun0" reference in the ioclient.c source by the interface of your choice (eth0 for example) Compile with:
gcc -o ioclient ioclient.c -lm
Run and push the button :)
##Control with sysfs: The driver can be controlled by sysfs. You just need to read or write to a virtual file in /sys/
###Backlight LCD
####/sys/class/dothat/sn3218/enable Value: 0 for disable , 1 or enable
echo 1 > /sys/class/dothat/sn3218/enable
####/sys/class/dothat/sn3218/lcd Set the color of one segment or get all color of segment
Get the color status:
cat /sys/class/dothat/sn3218/lcd
B: 0x00 0x00 0x00 0x00 0x00 0x00
G: 0x00 0x00 0x00 0x00 0x00 0x00
R: 0x00 0x00 0x00 0x00 0x00 0x00
Set the color blue to the segment 2
echo "2 FF0000" > /sys/class/dothat/sn3218/lcd
####/sys/class/dothat/sn3218/monocolor Set the same color for all segment or get all color of segment
Set the color red for all segments
echo "0000FF" > /sys/class/dothat/sn3218/monocolor
####/sys/class/dothat/sn3218/lcd_raw
Set the colors of segments in one time. You need provide a the 6 colors of the segments [BGR][BGR][BGR][BGR][BGR][BGR]
echo "0000FF00FFFF0000FF0000FF0000DF0000CC" > /sys/class/dothat/sn3218/lcd_raw
###TEXT LCD
####/sys/class/dothat/st7036/clear Write to it clear the screen and set the cursor to the position 0,0
echo 1 > /sys/class/dothat/st7036/clear
####/sys/class/dothat/st7036/contrast Use to control the contrast of the lcd. By default the value is 40 decimal. echo 40 > /sys/class/dothat/st7036/contrast
####/sys/class/dothat/st7036/cursor_on Set the cursor "_" to on or disable it echo 1 > /sys/class/dothat/st7036/cursor_on
For disable: echo 1 > /sys/class/dothat/st7036/cursor_on
####/sys/class/dothat/st7036/cursor_blink Blink the cursor echo 1 > /sys/class/dothat/st7036/cursor_blink
For disable: echo 0 > /sys/class/dothat/st7036/cursor_blink
####/sys/class/dothat/st7036/cursor_position The LCD have a 3 lines of 16 character. A "8 0" value mean column 8, row 0 echo "8 1" > /sys/class/dothat/st7036/cursor_position You can also get the current position with: cat /sys/class/dothat/st7036/cursor_position
####/sys/class/dothat/st7036/lcd_buffer Write on it write the text a the cursor position: Example: echo "2 0" > /sys/class/dothat/st7036/cursor_position echo "Hello World" > /sys/class/dothat/st7036/lcd_buffer
We set the cursor a the 2 0 and write "Hello world". The Hello world is centered at the first line.
####/sys/class/dothat/st7036/shift_display Shift the display with the correspondant value:
-
'>' character, shift the text to the right echo '>' > /sys/class/dothat/st7036/shift_display
-
'<' character, shift the text to the left echo '<' > /sys/class/dothat/st7036/shift_display
###Graph leds
####/sys/class/dothat/cap1166/blink
Blink the led at the blink_rate value. The leds is coded in one byte. Each leds is coded with a bit value. [LED 6 | LED 5 | LED 4 | LED 3 | LED 2 | LED 1 ]
To blink 5 / 3 / 1 its 010101 binary. In decimal the convert value is 21
echo 21 > /sys/class/dothat/cap1166/blink
####/sys/class/dothat/cap1166/blink_rate
Set the blink rate in ms echo 500 > /sys/class/dothat/cap1166/blink_rate
####/sys/class/dothat/cap1166/graph_bar Set the all 6 leds as a progress bar. The light value go from the top to the bottom 0 value mean 0% 255 value mean 100% echo 127 > /sys/class/dothat/cap1166/graph_bar
####/sys/class/dothat/cap1166/graph_bar_reverse Same as graph_bar except that the light value go from the bottom to the top
####/sys/class/dothat/cap1166/leds Enable the leds. The leds is coded in one byte. Each leds is coded with a bit value. [LED 6 | LED 5 | LED 4 | LED 3 | LED 2 | LED 1 ]
Enable leds light not mean that is light always on. If polarity is disable the led is light. If polarity is enable , enable the led light off the leds and disable light on.
####/sys/class/dothat/cap1166/luminosity Set the luminosity of the enable leds echo 144 > /sys/class/dothat/cap1166/luminosity
####/sys/class/dothat/cap1166/polarity Set the polrity of the leds. The leds is coded in one byte. Each leds is coded with a bit value. [LED 6 | LED 5 | LED 4 | LED 3 | LED 2 | LED 1 ] The polarity inverse the logical state of the specified leds. Example *led1 polarity is OFF led 1 is enable: led 1 is light on *led1 polarity is OFF led 1 is disable: led 1 is light off *led1 polarity is ON led 1 is enable: led 1 is light off *led1 polarity is OFF led 1 is disable: led 1 is light on
###Touch sensors: The touch sensors is recognized like a classic unix keyboard at /dev/input/by-path/platform-3f804000.i2c-event See the C example ioclient.c to handle. This example show the Bandwidth of a VPN tun interface in real time.
####Why the rainbox effect is in the client code and not directly hardcoded in the driver? To calculate a rainbow effect we use the HSV color transformation. This require floating point. Linus not recommanded to use floating point in kernel module and I'm agree.