Datasheet

User Manual Rev. 1.0 — 9 June 2017 11 of 14

NXP Semiconductors

UM11057

User Manual

6. Power measurement

JP2 is provided to enable supply current to the LPC845 to be measured by placing an

ammeter in line with JP2 pins. By default this jumper is bypassed by solder jumper (SJ6).

Header P1 may be installed to measure supply power to the LPC845 by measuring

voltage drop across a 2.43 ohm resistor on the board.

7. Other board features

This section describes other board features not detailed elsewhere in this document.

7.1 ISP booting and the ISP button

The LPC845 can be forced into ISP boot mode by holding down the ISP button (SW1) and

then holding and releasing reset. The ISP button is connected via a 100 ohm resistor to

LPC845 pin PIO0_12, which is also routed to the LPCXpresso expansion connector (pin

45) and to the cathode of the red user LED. LPC845 pin PIO0_12 can be reconfigured by

software so that the button can be used by an application as a general purpose button

(refer to the LPC84x User Manual).

7.2 Wake button

The Wake button is for general purpose use by LPC845 applications. It is connected via a

100 ohm resistor to a 100K ohm pullup to 3.3V, and to the LPC845 PIO0_4 pin. This pin

can wake the LPC845 from deep power-down. Note that PIO0_4 is also connected to the

P3 LPCXpresso expansion connector (pin 50).

7.3 User LEDs

Three users LEDs are provided on the board, one blue, one green and one red. The

anodes of the LEDs are connected together, through solder jumper SJ1 to the 3.3V

regulator output. SJ1 can be opened to prevent leakage from the LPC845 pins through

the diodes if accurate power measurement measurements are being performed. The

LEDs are connected to the LPC845 as shown in Table 6.

Table 6. LED connections

LED LPC845 pin Notes

Blue (D2) PIO1_15

Shared with LPCXpresso connector pin 44

Red (D3) PIO0_12 Shared with ISP pin and LPCXpresso connector pin 45

Green (D1) PIO0_0 -