NXP Semiconductors
UM10300
User Manual OM6290
UM10300_1
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 1.0— 8 August 2008
14 of 30
3.3.3 Block
diagram
mgs465
DISPLAY DATA RAM
MATRIX DATA
RAM
DATA LATCHES
MATRIX
LATCHES
COLUMN
DRIVERS
C0 to C127
PCF8531
R0 to R33
ROW
DRIVERS
COMMAND
DECODER
ADDRESS
COUNTER
DISPLAY
ADDRESS
COUNTER
TIMING
GENERATOR
OSCILLATOR
INTERNAL
RESET
POWER-ON RESET
ENR
RES
OSC
I
2
C-BUS
CONTROL
INPUT
FILTERS
SA0
SCL
SDA
SDACK
V
LCDOUT
V
LCDSENSE
V
LCDIN
T4
T3
T2
T1
34
V
SS2
V
SS1
V
DD1
V
DD2
V
DD3
V
LCD
GENERATOR
BIAS
VOLTAGE
GENERATOR
128
Fig 4. Block diagram PCF8531
4. The onboard microcontroller
The microcontroller chosen for this board is the LPC2148 which is a member of the NXP
ARM7 controller family. This microcontroller is based on a 16-bit/32-bit ARM7TDMI-S
CPU with real-time emulation and embedded trace support and embedded high-speed
flash memory of 512 kB. A 128-bit wide memory interface and a unique accelerator
architecture enable 32-bit code execution at the maximum clock rate. For critical code
size applications, the alternative 16-bit Thumb mode reduces code by more than 30 %
with minimal performance penalty.
The LPC2148 is highly over specified for the demo application program. This allows the
user to program the MCU with much more advanced applications. Also, it has some very
convenient features like an integrated USB interface and the possibility to program new
firmware versions in the embedded flash using In-circuit Serial Programming via the PC’s
serial port. This enables modifications in the firmware to be quickly evaluated.