LPC1833 Strange ADC behavier

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by hamu on Fri Nov 15 01:13:35 MST 2013

I want to convert all 8 ADC channels but the behavier is not as expected.

Example (V_ref = 2.5V):
Reading channel 5 with the CMSIS funcions

ADC_ChannelCmd (LPC_ADC0, 5, 1);
ADC_StartCmd(LPC_ADC0, 1);
while(!ADC_ChannelGetStatus(LPC_ADC0, 5, 1));
Value1 = ADC_ChannelGetData(LPC_ADC0, 5);
ADC_ChannelCmd (LPC_ADC0, 5, 0);

The result is always 0x3FF althought the value on the pin is 0,398V. With burst mode the conversion delivers the same result.
If I convert more than one channel in burst mode the conversion results depends on the number of activated channels. If I convert only channel 5 I get 0x3FF but when I convert channel 0 and channel 5 the conversion value for channel 5 is 0x190 (with same voltages on the pins).

Has anyone a working sample for the ADC??