Enforcing Regulated Fares at the Vehicle Level: An Offline ESP32 Meter for Auto-Rickshaws

Auto-rickshaws carry a large share of short-distance
urban trips in Bangladesh, yet most of them run without any fare
meter. Fares are settled verbally before each trip, and the gap
between what a driver asks and what a passenger expects to pay
is a common source of arguments. Commercial GPS taximeters
do not fit this market: they cost too much, draw too much
power, and depend on cellular data that many drivers cannot
afford. This paper presents a low-cost fare meter built around
the ESP32-WROOM microcontroller that runs fully offline. The
system measures distance from wheel rotation using an FC-03
optocoupler sensor read through a hardware interrupt, converts
pulse counts to distance with a calibration constant, and computes
the fare from a rate structure based on the government-notified
auto-rickshaw tariff. An L298N motor driver moves the prototype
chassis, an LM016L LCD shows the running distance and fare
to both driver and passenger, and a battery pack with a TP4056
charger and an LM2596S buck converter powers the unit. A
three-state controller (IDLE, ACTIVE, TRIP END) manages the
trip cycle and returns the meter to its starting state after each
trip. The fare model implemented in firmware follows a 20 tk
minimum with a 12 tk/km rate and rounds the display to the
nearest 5 tk, which matches how fares are actually settled on the
street. The prototype demonstrated stable pulse counting, correct
motor control, consistent power delivery, and a fare display that
tracked the measured distance during operation.