'µMeasure' Current Meter

This device employs low-side shunt resistors to measure current. When a configurable maximum shunt voltage is reached, a comparator switches the next latch to reduce the total shunt resistance by a factor of 10. When the voltage falls beneath a minimum shunt voltage, the resistance is increased by a factor of 10. By employing four stages of this, the device can dynamically measure currents from a couple microamps to about an amp.

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The current meter has an analog section to amplify and compare the shunt voltage while the digital section controls four D-flip flops used to latch resistor states. In the future, a microcontroller with 12-bit ADC and FTDI USB-UART bridge IC will be used to pipe current measurements over serial to a host PC. PySerial and various Python graphical packages will allow the user to configure the timebase, scale, and averaging factor for measurement.