Lab127 team.

HIGN SPEED USB MODULE OF NANONET STANDARD

According to the scheme below high speed USB-nanoNET module consists of nanoPAN radio, ATmega32L microcontroller and interface chip FT245RL. MCU performs low level control of transceiver and does frames preparation and data exchange with a computer.

ATmega32L is clocked by external 8 MHz quartz oscillator. The signals of SPI bus, RX and TX of USART are routed to pins of the corresponding connectors. The possibility of external power supply (for example for period MCU flash programming) is provided as well. ATmega32L and nanoPAN5631 have +3 Volt power supply, stabilized by ADP3330, which is connected to +5 Volt USB line. Antenna connector - SMA female.

Evaluation kit includes:

USB radio module of nanoNET (IEEE 802.15.4a) standard
Antenna 2.4 GHz
USB cable to a computer
Demo software for ATmega32L

TECHNICAL OVERVIEW

In the experiments on data transfer rate measurement with the use of a pair of USB modules the special embedded software was developed for ATmega32L. From the one hand it received the data from a computer through USB, formed the data packets and sent them to transceiver through SPI. And vice versa, it read the data received from radio ether and sent them to the computer. The moment of possibility of data transfer in forward and backward directions was determined by polling the state of FT245RL and reading the status registers of nanoPAN correspondingly.

The embedded software for both USB modules was practically the same (ATmega code differs only by MAC adresses assigned to transceivers).

USB radio modules were connected to different computers. On each of them the FTDI drivers were installed. Communication with FT245RL was carried out in the mode of Virtual Com Port. So Windows HyperTerminal was used as a communication software. After start of the software and hardware the symbols typed in one terminal were shown on the other and vice versa.

Hyperterm-nanoNET

To execute the long file transfer we used the function "Send File" with option "Z-modem with error recovery". The data transfer correctness was approved by testing the archive's integrity. Maximal data throughput of 720 kbps was achieved (see picture). The transceivers were configured with Acknowledgement option ON and maximum retransmissions equal to 3.