Leveraging high resolution capture for single wire data transfer
Pulse Width Modulation (PWM) is a powerful way of encoding analogue signal levels and is commonly used for controlling DC power to an electrical device. PWM can also be used for data transmission by varying the output pulse width proportionally with the data to be transferred, but a powerful decoding unit is required at the receiver.
Normal capture peripheral eCAP cannot support high transmission frequencies for high resolution data communication, which results in a high latency solution. However, HRCAP of C2000 operates over and above standard eCAP and is capable of measuring width of external pulses to a higher degree of accuracy compared to standard capture unit eCAP.
Thus, using HRCAP as a decoding unit at the receiver adds differentiation to the system by significantly reducing the latency for high resolution data transfer. The application report describes the high resolution peripherals of C2000 in brief and discusses the system implementation details. The document also discusses the software flow of both the transmitter and receiver examples and the achieved effective number of bits (ENOB) and latency at various transmission frequencies. Use Table 1 to choose various parameters while designing your own system.
The showcasing example configures F2838x as transmitter and F28004x as receiver, but the software can easily be ported to any C2000 device that supports HRCAP Type 1. Also in order to quickly evaluate the system, the single device loopback example is also provided where the same F28004x device is used as both transmitter and receiver.
To read the full paper, click here.