Simultaneous RFID Tag Reader Hookup Guide
Power Supply Considerations
The SRTR can be powered from the target board, the USB connection, or an external power supply.
USB Power (Good)
Standard USB ports will source up to 500mA. Because the Nano module can pull up to 720mA when powered from 5V the module will brown out and reset when operating at full read power. However, if read power is kept below 5dBm the SRTR can be evaluated using a simple USB-to-serial connection such as the FTDI Basic or Serial Basic.
USB power only. Limited to 5dBm read power.
External/Battery Power (Better)
There is a footprint available to install a 2mm JST connector or a 3.5mm screw terminal. LiPos work well to power the module, however, if using a LiPo battery (3.7V nominal voltage) you can expect to use more than 1000mA during full read power. Pick your battery size accordingly. Alternatively, the 3.5mm screw terminal may be installed to connect to external power such as a bench power supply.
LiPo Battery powering the RFID shield
Target Power (Best)
Powering the SRTR over the 5V pin from an Arduino works well if the Arduino has an external power supply such as a 5V wall adapter. If the Arduino is powered only by USB the module will brown out under full read power. It’s important to note that the shield gets its power from the 5V pin which means it’s drawing power from the onboard regulator of whatever platform you are using. If you provide your RedBoard with 9V and draw 1A through the 5V regulator it will get red-hot. Use a 5V power adapter to reduce the thermal strain on your regulator.
RedBoard with 5V adapter attached