Hi Rob,
I've no direct resolution to your problem.
But maybe some ideas...
But I have quite similar effects on a QD4 part, which I want to operate at variable Vdd in range 3.0 Volt ... or 4.5 ... 5 Volt.
I use Cyclone Pro, feed power from my variable power supply to power-in-jack of CyclonePro.
From power-out-jack, the connection goes to Vdd of my target.
Only jumper no. 5 of CyclonePro is selected.
I made a support request to PE Micro (supplier of CyclonePro) and they did tell me that this is the right connection.
1.) Debugging ADC with active BDM
My function on QD4 should measure it's Vdd, by use of the known internal bandgap reference.
10 bit ADC mode is used.
In general, this works.
But I've found that there ist a lot of traffic on the BDM line.
This results in a significant noise (ripple) also on the Vdd and makes the measurement UNUSABLE, when BDM is connected.
This does also taking place when in "RUN" mode , even if no debug window is selected for periodic update.
I've not made final tests, if all these windows are manually put into "frozen" state...
This means: Debugging of small ADC signals, espacially Vdd, is hard to be done with active BDM traffic.
I've not found a option like "disable BDM traffic when in RUN mode".
2.) Endless waiting for COCO with single-step:
I also have the problem you wrote about:
...
92: while (!ADCSC1_COCO) { ; /* wait */ }
0000FA43 0F10FD BRCLR 7,0x10,*+0 ;abs = 0xFA43
...
In single step mode, the debugger always wait endlessly in the BRCLR loop...
But: This is independent from Vdd , at my target.
--> Maybe the other windows in real-time-debugger ( e.g. "memory" ) does disturb the COCO flag reading, especially when pointing to the area of the internal io registers.
This suspicion I have.
3.) Other debugging problems and hints:
Also, my activated PWM output signal stops in debug mode ... I don't know if this is normal behaviour.
I've not found any option like "don't stop peripherals in single-step mode".
Another point is, that there is only a single breakpoint.
If a breakpoint is set by me, single-step is possible, but no "step out". For this feature, a temporary breakpoint would be required, which is not available any more...
Rob, if you have different effects on 3V vs. 5V, also look to the settings (and defaults) for low voltage detect.
On my QD4, this is SPMSC2_LVDV , SPMSC2.
My conclusion is: Very hard debugging for these small uP.
And strange behaviour sometimes.
===> If somebody else is reading this message, and does have some ideas or knowledge about the debugger, please ANSWER !
Klaus