NXP Semiconductors
UM10744
OM13500 & OM13500A user manual
UM10744
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© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 23.September 2013
7 of 14
cases, communication with the LCD driver is through the I
2
C-bus. This are pins 40
and 41 of the LPCXpresso connector.
•
IDD_IC3: This jumper is not soldered onto the board during manufacturing.
Instead, a 0 Ω resistor (R11) is mounted, in parallel with this jumper. Removing the
0 Ω resistor and mounting the jumper makes it easy to insert a current meter and
measure the current consumption to the Vdd pins of PCA9620. After
measurements, a jumper header can be inserted.
•
IDD_IC8: This jumper, along with 0 Ω resistor R17 fulfills the same function as
IDD_IC3, but for the PCA8537. Note, that either PCA9620 or PCA8537 is
mounted, never both.
In addition a few SMD 0 Ω resistors are mounted for I
2
C address selection. The
expectation is that these will seldom be removed, but it allows selecting a different I
2
C
slave address for PCA9620 (resistors R4 – R7) or PCA8537 (R18 and R20), without
cutting tracks on the PCB.
2.5 Use of internal / external oscillator
Both LCD drivers offer the option of using the internal or an external oscillator. This can
be set using the configuration registers. If the internal oscillator is used, the oscillator
signal is available at connector “CLK”. If an external oscillator signal is used, this can be
supplied to the LCD driver using this connector “CLK”.
2.6 Connectors
Besides the previously mentioned connectors, connector P2 contains the I
2
C and SPI
signals, along with V
SS
and a reset signal. This connector can be used to connect the
baseboard to another application / microcontroller. In that case, the LPCXpresso board
must be removed.
3. Board schematic and layout
On the next pages the circuit diagram and PCB layout of the board are given. Refer to