The Internet connectivity in electronic devices has
been progressively increasing over the years. While radio frequency
(RF)-based communications dominate Internet of Things
(IoT) applications, they face some issues such as interference and
spectrum limitations. Visible light communications (VLC) uses
light emitting diodes (LEDs) lights with intensity modulation to
convey the signal and it has been demonstrated as a viable alternative
for indoor IoT scenarios. On the other hand, data clock
synchronization between the transmitter (Tx) and the receiver
(Rx) is crucial for reliable data transmission, mitigating timing
errors and packet losses. Typical implementations are complex
and require high-speed processing. This paper introduces an
algorithm for data clock synchronization in a hybrid multiband
carrierless amplitude and phase (m-CAP)/quadrature amplitude
modulation(QAM) VLC system for IoT devices, ensuring accurate
clock recovery that can be implemented in a low-cost
microcontroller. The system achieves synchronization with a clock
mismatch tolerance of up to 4200 ppm, supporting frames with
a payload length up to 624 octets. By using averaging window
sampling instead of a single sample acquisition, it is possible an
extension of the payload length by approximately 208 octets.