Datasheet

User Manual Rev. 1.0 — 9 February 2018 13 of 16

NXP Semiconductors

LPCXpresso804

User Manual

8.3 DAC/ADC continuity tester circuit

The PLU shield includes a simple circuit to implement a continuity tester, as shown below.

By enabling PIO0_11 as a DAC output, a test signal can be driven to a circuit probe

connected to JP3, then the voltage at the voltage divider formed by R18 and R20 can be

measured using an LPC804 ADC input (PIO0_19). In order to use this circuit it is

recommended that R15 is removed and S3 set to the VCC position.

9. Capacitive Touch Shield

The OM40001 package includes a shield board for evaluation of the LPC804 capacitive

touch feature. The Capacitive Touch Shield provides the following features:

• 5 capacitive touch buttons

• 5 LEDs, available for user applications (typically to indicate a button press)

The connections for the capacitive touch buttons are shown in Table 9. As some signals

are shared with other functions, the jumpers shown in the table should be removed from

the LPCXpresso804 board when using the capacitive touch shield.

D6 PIO0_20 JP11

D7 PIO0_7 JP4 I

C connections also used for LM75. Remove JP23

to isolate.

D8 PIO0_14 JP5 I

C connections also used for LM75. Remove JP23

to isolate.

Table 8. PLU shield LEDs

LED LPC804

signal

Jumper installed

to enable

Notes

Table 9. Capacitive touch button signals

Button LPC804 I/O Capacitive touch signal Shared with / remove jumper

S1 PIO0_12 CAPT_X0 User LED / JP22

S2 PIO0_21 CAPT_X1

S3 PIO0_13 CAPT_X2 User LED / JP25

S4 PIO0_11 CAPT_X3 User LED / JP21

S5 PIO0_19 CAPT_X4