I have just started writing a simple application for the LPC2129. I have a problem with polling the DONE bit of the ADC. The ADC clock is 3.68 MHz. I set the ADC to be 10 bits, single shot. I start the ADC and then poll the done bit like this:- while( !(ADDR & 0x80000000) ); The code is compiled using the Keil ARM tools (demo version). When I run the code on the simulator it works correctly, when I run it on the target it returns incorrect values. The returned value does track the input voltage but is quantised to 0x0000, 0x6000, 0x8000 or 0xE000 (Only 4 discrete values). If I single step or place a delay function before polling the DONE bit then the code runs correctly. Am I doing something wrong or is there a problem with polling this bit?