User manual

LPC3250 Developer’s Kit v2 - User’s Guide

Page 59

information about appropriate management of invalid blocks can be found in technical notes and

datasheet from Samsung.

5.6.3 Brand of Memory Chips

Note that there is no guarantee for a certain brand or version of memory chips; SPI-NOR flash, parallel

NAND flash and mobile DDR SDRAM. The lifetime of memory chips is limited and availability can also

be limited from time to time. Embedded Artists make every effort to mount the original design chip on

the board. In case that is impossible a compatible chip will instead be mounted without any prior

notice. There can be small programming differences between mounted brands. The application

program shall always read the chip id of flash devices to make certain which chip is actually mounted

on the board.

The support page contains datasheets to the different memory devices and information about mounted

devices on different board versions.

5.6.4 LPC3250 Peripherals

The key scan interface peripheral cannot be used with the LPC3250 OEM Board because the Ethernet

interface is active.

5.6.5 Current Consumption and Limits of USB Ports

The current consumption of LPC3250 OEM Board, OEM Base Board, and the 4.3 inch LCD Board is in

the region of 90-150mA. This is below what a normal USB-A port can supply. However, if the boards

are powered from a USB-A port (for example a PC or laptop) and there are problems, like spontaneous

resets or other strange things, it is likely that an external power supply is needed. Powering via a USB

hub is also a possibility.

When using the 7 inch LCD Board an external power supply is always needed. A normal USB-A

port cannot supply the needed current when the 7 inch LCD is used.

5.6.6 LCD flickering

When using the LCD expansion interface, R163 must be removed on the OEM Base Board. If not, the

LCD can start flickering and the blue component of the pixel color can disappear for short time periods

(= the flickering). If the picture is mainly blue it will look like a black row on the display. If other colors

are dominating on the picture shown, it can also look like yellow lines (white minus block color

component result in a yellow color).

The reason for this problem is that the I2C interface of the MIC2555 USB OTG transceiver is

connected to the two MSB signals of the blue color component. Even though the pixel data is very

much out of spec for the I2C interface, the MIC2555 reacts on some sequences and start driving the

MSB signal low, which is the flickering that is seen. The solution is to remove resistor R163.

The LCD interface and the USB OTG transceiver cannot be used at the same time on the OEM Base

Board.