NXP Semiconductors
UM10300
User Manual OM6290
UM10300_1
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 1.0— 8 August 2008
6 of 30
2.4 Connectors
On the left below LCD3 a pin strip P3 is available which carries the following signals: 5V,
3V3, SCL, GND, SDA and nRES. The latter is connected to the reset circuit IC6 and by
making nRES LOW, a defined reset signal is generated.
On the right side of the board a USB connector has been provided. At the time of writing
the first revision of this manual the only purpose of the USB connector is to offer the
option of powering the board via USB. Future updates of the firmware which would also
enable data communication between the LCD driver ICs and a GUI which then would run
on a PC, are under consideration.
The serial interface RS1 (UART) below the USB connector is used for updating the
firmware in the microcontroller.
2.5 Reserved components
The board layout includes a few components which are not directly necessary for the
primary purpose of the board which is providing a hands-on tool to work with the three
different types of NXP LCD drivers. Therefore these components are not mounted.
However, in some scenario’s it may be desired to explore more of the options of the on-
board microcontroller. Therefore three optional areas may be mounted by the user of the
board in order to add extra functionality.
1. Real Time Clock of LPC2148: By mounting a 32.768 kHz crystal at position Y2 as
well as two capacitors at positions C29, C30 the internal RTC can be used. The
values of C29 and C30 depend on the crystal used. A crystal for an RTC is designed
to operate with a certain load capacitance C
L
. A common value for the required load
capacitance of such a crystal is 12.5 pF. Seen from the crystal C29 and C30 are in
series. Taking into account parasitic capacitances as well, C29 and C30 will have to
be 22 pF or 25 pF if a 12.5 pF crystal is used.
2. JTAG interface: On the right side of the board under LCD1, space is provided for a
JTAG connector. This is a 20-pin header with pitch of 2.54 mm. The required pull-up
resistors are already mounted.
3. Pin strips P1 and P2 near the bottom edge of the board. If a pin strip is soldered on
the board at this position, all unused pins of the microcontroller are accessible.
If mounted, exercise caution not to overload these signal lines !
Besides these microcontroller related items, another option is to remove resistor R29
(470
Ω
) and mount potentiometer Pot1 (4k7) instead. This enables adjustment of the
contrast of display LCD3. The location of these components is between LCD2 and LCD3.