Product Application

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Rev.1.1
3. FT801 and FT813 specific functionality
All FT8xx chips share exactly the same graphics feature sets. The touch capabilities of the FT800 and
FT812 devices are designed for controlling touch on a resistive panel, while FT801 and FT813 are for
capacitive touch and allows simultaneous up to 5 touch points. Therefore, the FT801/FT813 have a
different touch engine and touch control register set from the FT800/FT812. All the registers which
name starts with “REG_TOUCH” have been assigned to new name “REG_CTOUCH”. By default, the
FT800 and FT812 touch engine work in compatibility mode and only one touching point is detected. In
extended mode, the FT801 and FT813 touch engine can detect up to 5 touching points simultaneously.
3.1 Sketch function in capacitive touch panels
In FT801 chip you must to use CMD_CSKETCH instead of the CMD_SKETCH. This command has the
same functionality as CMD_SKETCH except it has done the optimization for a capacitive touch panel.
Because capacitive touch panels have lower sampling frequencies (around 100Hz) to report the
coordinates, the sketch functionality updates less frequently compared to resistive touch.
CMD_CSKETCH introduces a linear interpolation algorithm to provide a smoother effect when drawing
the output line. Please note this command is not applicable to FT800 and FT812 silicon. Code below
shows how to use this function. Last parameter is sampling frequency.
Ft_Gpu_CoCmd_CSketch(phost, BorderSz2,BorderSz,(FT_DispWidth -
2*BorderSz2),(FT_DispHeight - BorderSz -
BorderSz2),(RAM_G+ending_address),L8,9000);//sketch in L8 format
3.2 Multi-touch usage
In this example, the method for handling multi-touch is presented. You will see on the blue screen
white text “Please Tap from 2 to 5 points”. You can touch up to 5 points simultaneously. After touching
the appropriate polygon will be displayed.
Figure 9. Multi touch demo