LPC1837 ADC Problem

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by Cusko on Mon Mar 11 04:31:32 MST 2013
I discovered some problems with an ADC on the LPC1837.

1. If I initialize an I2C1 with the ports (P2_3 and P2_4) then  the ADC0_1 and the ADC0_3 show some values even if they are zero. And when the ADCs have some value they have also some offset. Only if I lower a processor frequency to 24Mhz the ADCs show correct value or if I turn the I2C initialization off.

2. If I don’t have a sensor connected on the ADC0_3 and  the ADC0_1  has some value, then ADC0_3 shows some value too. If ADC0_1 doesn’t have any value then ADC0_3 is zero too. If a sensor is not connected the ADC0_3 value must be zero and must not be correlated to value on the ADC0_1. (In the case of the problem 2 the I2C was not initialized.)

Is this some kind of errata or what?