BMSKTOPASA900(DCE) Toshiba, BMSKTOPASA900(DCE) Datasheet - Page 745

• Manufacturer Part Number: BMSKTOPASA900(DCE)
• Description: KIT STARTER TMPA900 USB JTAG
• Manufacturer: Toshiba
• Series: TOPASr
• Type: MCUr

Specifications of BMSKTOPASA900(DCE)

• Contents: Evaluation Board, Cable(s), Software and Documentation
• For Use With/related Products: TMPA900CMXBG
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Touch screen resistor
The resistance depends
on the touch screen.
SMY (SMX)
ON-resistor: Rmy (Rmx)
SPY(SPX)
ON-resistor: Rpy (Rpx)
: Rty (Rtx)
3.21.4
10 Ω (typ.)
10 Ω (typ.)
measuring following the procedure below:
X/Y Position Measuring Procedure
<X-position coordinate measurement>
<Y-position coordinate measurement>
During the routine of pen-touch and INTA interrupt generation, execute a pen position
setting, an analog voltage that shows the X position will be input to the PD5/MY/AN5
pin. The X-position coordinate can be measured by converting this voltage into digital
code using the AD converter.
setting, an analog voltage that shows the Y position will be input to the PD4/MX/AN4
pin. The Y-position coordinate can be measured by converting this voltage into digital
code using the AD converter.
measurement above can be determined with the ratio between the ON resistance value
of the switch in the TMPA900CM and the resistance value in the touch screen as shown
in Figure3.21.5
voltage will be neither 3.3 V nor 0 V.
during designing. It is also recommended that an average taken from several AD
conversions performed if required be adopted as the final correct value.
Make the SPX and SMX switches ON, and the SPY and SMY switches OFF. With this
Make the SPY and SMY switches ON, and the SPX and SMX switches OFF. With this
The analog voltage which is input to the AN5 and AN4 pins during the X and Y position
Therefore, even when touching an end area on the touch screen, the analog input
Note that the rate of each resistance varies. Remember to take this into consideration
AVCC3AD = 3.3 V
R2
R1
Figure3.21.5 Analog input voltage calculation values
Touch point
AN4 (AN5) pin
TENTATIVE
TMPA900CM- 744
[Analog input voltage to the AN4 and AN5 pins: Formula to calculate E1]
Example) Where
Note 1: An X-coordinate position can be calculated in the same way
Note 2: Rty = R1 + R2
AVCC3AD = 3.3 V, Rpy = Rmy = 10 Ω R1 = 400 Ω and R2 = 100 Ω
though above formula is for Y-coordinate position.
E1 = ((R2 + Rmy) / (Rpy + Rty + Rmy)) × AVCC3AD[V]
E1 = ((100 + 10) / (10 + 400 + 100 + 10) × 3.3
= 0.698 V
TMPA900CM
2009-10-14