CoolRunner-II-Based Digital Telemetry Transmitter

摘要

With the inroads that programmable logic has made into CPU interfaces, new versions of these JTAG programmable devices have now gained sufficient bandwidth to directly transmit wireless data. Take a look around. Integrated wireless ICs abound, and wireless data communication builds on each part's RF capabilities. Although many off-the-shelf products for wireless data transmission are available, that usually means living with someone else's design decisions that may not match the design requirements you have in mind. And, if you're working on a battery-powered wireless system, then power draw and reception range are likely two features of the circuit design that you'll need to optimize. For sensor applications, though, it's easy to build a simple low-power, moderate-speed wireless link that you can add to a battery-powered microcontroller circuit to transmit one-way information such as temperature, pressure, or something more dynamic and complex like acceleration. As an embedded programmer, you know the versatility of a serial datastream. Let's consider the circuit needed to take that serial data onto the wireless highway, and then, with the help of a commercial radio receiver, build a local off-ramp for your serial data. Through all of these transformations, keep in mind that wireless data transmission might just as well be called making electromagnetic interference (EMI) work for you as digital radio.