Datasheet

NXP Semiconductors

UM11121

LPCXpresso51U68

UM11121

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User manual

Rev 1.1 — 27 April 27, 2018

16 of 22

7. LED indicators

The LPCXpresso51U68 board LED locations are shown in Fig 2. A description of each

on-board LED indicator is shown in Table 3.

Table 3. LED indicator functions

LED reference

Description

Link2 MCU BOOT0_LED indicator. Reflects the state of Link2 MCU P1_1.

When the boot process fails, D1 will toggle at a 1 Hz rate for 60 seconds.

After 60 seconds, the Link2 MCU is reset. It will be ON when the Link2

MCU is Booting using DFU (See description for JP6).

Tri-color LED – Driven by Target LPC51U68 MCU. The red led is driven by

P0_29. The green led is driven by P1_10. The blue led is driven by P1_9.

LEDs are on when the LPC51U68 port is output low. By default the 0Ω

resistor at JS17 provides the shunt for JP6. To measure the lowest

possible current from LPC51U68 remove the 0Ω resistor at JS17 (remove

+3.3V from led common anode). After removing JS17, to light any of the tri-

color leds, JP8 must be installed.

Target LPC51U68 power LED. This LED is on any time power is applied to

the Target LPC51U68 MCU. LED will have a brighter intensity when the

LPC51U68 is powered from +3.3V than when powered by +1.8V.

Target Reset LED. This LED is on anytime the Target RESETn is pulled

low.

8. Expansion connectors

The LPCXpresso51U68 board includes four expansion connectors plus a PMod™

compatible connector (J3). The expansion connectors (J1, J2, J7 and J8) incorporate an

Arduino Uno revision 3 footprint in their inner rows. Not all connector locations are

populated on the expansion connectors since the LPC51U68 does not have enough I/O

to utilize all of the available connections (additional pin locations are provided for

compatibility with future LPCXpresso boards).