Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK Datenbogen
Produktcode
AT91SAM9M10-G45-EK
898
SAM9M10 [DATASHEET]
6355F–ATARM–12-Mar-13
40.7.2
Position Measurement Method
As shown in
linear resistance of the film, there is a voltage gradient from top to bottom. When a contact is performed on the
screen, the voltage propagates at the point the two surfaces come into contact with the second film. If the input
impedance on the right and left electrodes sense is high enough, the film does not affect this voltage, despite its
resistive nature.
screen, the voltage propagates at the point the two surfaces come into contact with the second film. If the input
impedance on the right and left electrodes sense is high enough, the film does not affect this voltage, despite its
resistive nature.
For the horizontal direction, the same method is used, but by applying supply from left to right. The range depends
on the supply voltage and on the loss in the switches that connect to the top and bottom electrodes.
on the supply voltage and on the loss in the switches that connect to the top and bottom electrodes.
In an ideal world (linear, with no loss through switches), the horizontal position is equal to:
VY
M
/ VDD or VY
P
/ VDD.
The proposed implementation with on-chip power switches is shown in
the output of the switch compensates for the switches loss.
It is possible to correct for the switch loss by performing the operation:
[VY
P
- VX
M
] / [VX
P
- VX
M
].