EarthLCD ezLCD-405, Руководство пользователя

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e z L C D -­‐ 4 0 5 | 40
Rev.
© 2016 Earth Computers Tech. Inc.
1.5.3.3 CalibratedXY
When the CalibratedXY protocol is selected, the ezLCD:
·∙ ezLCD sends TOUCH_X and TOUCH_Y packets (X and Y coordinates), when the screen is
pressed
·∙ ezLCD sends PEN_UP packets when the touch screen is not pressed.
·∙ Packets are sent continuously, 5 to 50 times per second.
In order to select the CalibratedXY protocol, send TOUCH_PROTOCOL (64) to the ezLCD.
Sending of the touch screen coordinates by the ezLCD
The touch screen coordinates are sent by the ezLCD only when the CalibratedXY protocol is
selected.
For ezLCD-­‐405: Xmax= 319 Ymax= 233
Touch screen coordinates are sent in multi-­‐byte packets:
·∙ Packets are sent in non particular order
·∙ Each packet is starts with the PACKET_ID byte
·∙ Each packet is identified by it's PACKET_ID byte
·∙ The PACKET_ID may be followed by the data bytes, however there are packets which only
consist of the PACKET_ID with no data bytes
·∙ Bit 7 of the PACKET_ID is always 1
·∙ Bit 7 of the data bytes is always 0