Bearing in mind that the goal of this project is to create a tool that makes it easier to debug and optimize devices that need to operate on very low power, I think that the clogger should have at least the following features:

• The clogger should be able to accurately measure currents down to ~+/-5 uA.
• It should be able to measure the supply voltage for the device under test.

• The analog to digital converter should sample fast enough to measure current spikes only 10usec long. It is not uncommon for microcontrollers to turn on peripherals for only microseconds.
• The amplifier should have a high bandwidth. Signal features lasting only 10usec should not be significantly attenuated. That is going to be tough.
• The clogger should be possible to feed the amplified current measurements directly out to an oscilloscope (in addition to feeding it out to the ADC).
• It should be possible to log measurements directly to an SD card.
• It should be possible to stream average measurements to a computer.
• The device under test should be able to send markers to the logger.
• The computer should be able to send commands to the logger to enable, disable, and control features.
• If it is necessary to have multiple ranges, it should warn users if they are measuring outside the safe range.
• The power supply input for the device under test (DUT) should be over-voltage protected and reverse current protected. Overvoltage events should trigger warnings visible.
• The device should have a button to start/stop logging and an led to indicate whether logging is in progress.
• The clogger should have an LED indicating when it has received messages from the device under test.
• The clogger should have an LED indicating when it has received a message from the computer.

There are plenty of other features that would be nice, but not essential:

• An onboard display showing the average current over the selected time window would be nice.
• A potentiometer for adjusting the time window on the fly would also be nice.
• Alternatively, it might be nice to support a bluetooth interface to allow users to check average current measurements using their phones.
• It would be fantastic to include a high resolution onboard display with a high refresh rate to display real time current measurements.
• It would be nice if the clogger could operate as a standalone device (without being attached to a computer). That would mean having its own power supply.

Based on these features, there are really just three main systems: the amplifier, the analog to digital converter, and the controller (which includes the sd card, the led indicators, and all the communication systems).