When I received my ZT-280 C91 and let it boot for the first time, I did not yet remove the thin transparent plastic display cover.
At the end of the boot processes, the touchscreen was calibrated automatically, though I did not pay much attention to that.
When I then tried out using the tablet (with the plastic cover meanwhile removed), the touch screen behaved extremely erratically:
for most time it did not respond at all, and when it did, it behaved in a totally wrong way, producing random 'phantom' touches.
I attach a video clip for demonstration: ZT280C91_miscalibrated.wmv 7.56MB 74 downloads.
This made the tablet absolutely unusable, since apps, settings, etc. could not be controlled.
I complained at the online shop and was already preparing to send back the item. Yet meanwhile I got a second tablet of the same kind,
which worked fine. When I updated its firmware, I realized the calibration process and got the idea that I could try the same with the
'broken' tablet. During re-installing, I made sure not to touch its display while calibrating, and then all the problems were gone!
So it turns out that my mistake was not to remove the plastic protection of the display right at the beginning.
Interestingly, the tablet comes with a CapTouch applet, which seems to work on the 2N version, but not on the 3a version.
On the latter version, running the recent ZT280_H1_3a_C91_Android4.0_0206_V1.5 firmware I had downloaded from Zenithink,
the calibration app has no effect. Calling /system/bin/android_I2C_Calibrate_V1_0 manually from the shell prints
apparently because /dev/pixcir_i2c_ts0 does not exist. The logcat output contains:
W/CapTouch( 2032): wait 2 seconds
E/logwrapper( 6724): executing /system/bin/android-I2C-Calibrate-V1.0
failed: No such file or directory
I/logwrapper( 2032): /system/bin/android-I2C-Calibrate-V1.0 terminated
I/ ( 2032): com_zt_CapTouch_CapTouch_execCapPixcir : rc = 255
I/ ( 2032): open '/sys/devices/virtual/input/mice/name' failed
I/ ( 2032): '/sys/devices/virtual/input/input0/name' 'ecompa'
I/ ( 2032): Couldn't find or open 'calibration' driver (No such
file or directory)
W/CapTouch( 2032): myFile : /proc/driver/nastech
W/CapTouch( 2032): myFile is failed
W/CapTouch( 2032): fout = null
Edited by DvO, 19 February 2012 - 01:03 AM.