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Issue #211 February 2008
RFID Payment Terminal
by Carlos Cossio
Start | System Overview | Energy Transmission | 100% Amplitude Modulation | Load Modulation | MIFARE Card | MIFARE and ISO 14443 | Pay as You Go | Hardware Design | Antenna Design Rules | Antenna Size | Directly Matched Antenna | Firmware Design | Catch the Wave! | Sources & PDF
FIRMWARE DESIGN
I developed all of the firmware with the help of an ARM Keil mVision 3 IDE with a RealView compiler toolset. You may download a trial version limited to 16 KB of code generation (www.keil.com/arm). The firmware for the RFID payment terminal requires the installation of the Stellaris driver library (a set of drivers for accessing the peripherals found on the Stellaris family of ARM Cortex M3 microprocessors) in the Keil distribution package.
All of the software has been developed in a modular and hierarchical way and in C language, so maintenance and improvements are fairly simple to perform (see Figure 7).
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| Figure 7—The module hierarchy for the firmware is fairly simple. There are different layers of complexity. Each microcontroller peripheral has its own driver in a separate source file. There is no need for an RTOS. |
A description of the modules and the functions included in every module is posted in the Software Modules pdf on the Circuit Cellar FTP site.
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