Using theLPCXpresso11U68 Evaluation Board, the "periph_adc" example has a warning and an invalid configuration.
The code is from: lpcopen_3_01_lpcxpresso_lpcxpresso_11e68
The warning is in Chip_ADC_StartCalibration() because the variable save_ADC_CTRL is set but not used. Removing the declaration and assignment resolves the warning.
The invalid configuration is in the IOCON setup:
/* ADC input 8 is on PIO0_12 mapped to FUNC2 */
Chip_IOCON_PinMuxSet(LPC_IOCON, 0, 12, (IOCON_FUNC3 | IOCON_MODE_INACT | IOCON_ADMODE_EN));
The code sets the pin to Function 3 which is for the CT32B1 peripheral. The comment is correct, Function 2 is for ADC_8. Oddly enough, the ADC actually works with both Function 2 and 3, but Function 2 is specified in the User's Manual Rev. 1.8.