WM_PRJ_Q2400_PTS_005 -007
18th January 2006
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2.1.3.3 Decoupling of power supply signals
Decoupling capacitors on VBATT and VDD lines are imbedded in the module. So
it should not be necessary to add decoupling capacitors close to the module.
However, in case of EMI/RFI problem, some signals like VBATT and charge line
(CHG_IN) may require some EMI/RFI decoupling: parallel 33 pF capacitor close to
the module or a serial ferrite bead (or both to get better results).
In case a ferrite bead is used, the recommendation given for the power supply
connection must be carefully followed (high current capacity and low
impedance).
2.2 Digital I/O and peripheral implementation
2.2.1 Electrical information for digital I/O
All digital I/O comply with 3Volts CMOS.
To interface the WISMO Quik Q24x6 sub-series digital signals with other logics:
•
3.3 V logic: some serial resistors (more than 11k
Ω
) can be added on the
lines,
•
For higher voltage logics, a resistor bridge or a level shifter IC can be
added.
2.2.2 LCD interface
The WISMO Quik Q24x6 sub-series can be connected to a LCD module driver
through either a SPI bus or a two-wire interface.
2.2.2.1 SPI bus
The SPI bus includes a CLK signal (SPI_CLK), an I/O signal (SPI_IO) and an EN
signal (SPI_EN) complying with SPI bus standard.
