User`s guide

LPC3250 Developer’s Kit v2 - User’s Guide
Page 25
Copyright 2012 © Embedded Artists AB
4.12 SP8: Digital IO
There is a push-button (SW6) that is connected to a signal that enable the service mode after reset on
the OEM Board. For the LPC3250 this is pin GPI_01. If this pin is sampled low after reset, the uart
service mode for the LPC3250 is entered (allowing program code download to internal SRAM via
UART #5). LED30 is positioned above SW6 and will light when SW6 is pressed. It is also possible to
control LED30 as an output from the OEM Board without damaging the output driver when SW6 is
pressed. R110 limits the current.
There is also a 5-key joystick that directly connects to five general purpose input/output pins. See
picture below for locating SW6 and SW7.
Figure 11 – Digital IO
Signals
LPC3250
GPIO_10
GPI_01
GPIO_73
P2.0
GPIO_74
P2.1
GPIO_75
P2.2
GPIO_76
P2.3
GPIO_77
P2.4
4.13 SP8: Serial Expansion Connector
The Serial Expansion Connector is a standardized serial interface connector that is included on many
boards from Embedded Artists, including the OEM Base Board. The purpose is to provide a simple
expansion connector for smaller expansion modules. Such modules are typically sensors of different
kinds and communication modules, but can also be smaller displays.
The connector contains 14 pins that support SPI, UART and I2C communication. Four additional pins
exist for specific functionality, like module reset, interrupt pins, analog signals and pwm signals. Power
(3.3V) is also provided. Maximum current consumption of the external module is 250mA. All signals
are protected with 470 ohm series resistors to minimize current in case of shorts to ground, +3.3V, or
similar.
Usage of the different signals is specific for each module connected. All signals can be configured as
either main function or alternatively as a general purpose input/output signal (GPIO). The picture below
show where the connector can be found and the table lists which pins are connected. The application
program has the responsibility to program the individual pins to correct state/function.
Note that the UART channel is not directly connected to a UART channel on the LPC3250. It is
multiplexed with other UART channels, see section 4.15 for details. Also note that the Serial Expansion
Connector and the RF-module (see section 4.14 ) share the same UART channel. Once the RF
module is soldered, the Serial Expansion Connector cannot be used for UART communication.
5-key Joystick
SW7
Push-button
SW6