Creating an RF RSSI Sniffer Tool for Car Access Systems

By Chris Wunderlich and George Rueter

By reconfiguring the Atmel ATA5830N UHF transceiver chip through a simple method using its Flash program capability, you can create a received signal strength indicator (RSSI) monitoring tool that you can use both in a lab setting as well as in a vehicle.

The ATA5830N chip integrates a high-performance UHF transceiver with a low-power Atmel AVR 8-bit microcontroller. The device also has 6KB of Flash memory—this Flash memory space is what you can use to develop an application for an RSSI monitor that generates USART-formatted messages with RSSI data.  

To create the RSSI monitoring tool, we developed the software using the ATAK51002-V1 evaluation kit, a +5V power supply and the RF signal input. The kit includes a reference design that consumes about 9mA when running our application—low enough to support battery operation. Once we powered up the reference design, we awakened the ATA5830N device by momentarily connecting any of the “npwron” pins to ground or the “pwron” pin to +5V. Once the part was awake and active, we didn’t need to provide additional input and the RSSI data was available at PC3 pin 17.

Using the EEPROM configuration file, we programmed desired radio parameters into the part. You can select these values using an Excel spreadsheet tool that automatically generates the EEPROM file. Once we programmed the values into the EEPROM, the application of power automatically initiated the self-configuration and execution of the Flash application program.

You can use the resulting application for several common RF engineering tasks, including RF environment analysis, performance tuning of the receiver section, RF component selection and antenna performance evaluation. For diagrams and the full details about creating the RSSI tool, read our full article, “RF RSSI Sniffer Tool for Car Access Systems.”