I saw a different H-bridge circuit than the H-bridge circuits I’ve seen before. What could the connection to the MCU in the lower left of the circuit be for?
The resistor on the right is a "shunt" resistor. This is a small value resistor which is used to measure the current flowing into the motor down to ground (U = Rshunt*I). The same voltage is developped across the RC circuit. This circuit is a low-pass filter. This will ensure that only the average DC current will be measured by the MCU. The "MCU" output from the RC filter must be connected to the MCU's ADC for measurement.