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eZ430 RF5509 USB Stick

This is a USB stick kit from Texas Instruments that is suitable for OpenTag development or evaluation. It uses the MSP430F5509, and OpenTag supports the onboard USB. The Demo_PaLFi Master (Gateway) application is the typical application for this board.

Hardware Overview


The cut PCB is approximately 48x15mm. The approximate bounding dimensions, including the USB port connector (Type-A male), are 62x15x6mm. The dimensions make it one of the most compact OpenTag boards available today.


Integrated Antenna

The chip antenna and integrated balun from Johanson (0433BM15A0001) are designed specifically for the CC430/CC1101, so they allow an extremely compact form factor.

Spy-Bi-Wire Programming

The 4-pin Spy-Bi-Wire interface can be used to load programs or debug. The 1.27mm 4-pin header is not included, so you must add one yourself. The soldering is not terribly difficult when using a fine-tip iron, but the PCB wiring of connection itself is quite frangible, and it is easy to damage the board if you put too much strain on the 1.27mm 4-pin header.

NOTE (JP): I recommend soldering a Spy-Bi-Wire eZ430 interface directly to this board if you plan on doing extensive test & debug.

Internal Schematics

The primary components of the design are:

  • MSP430F5509 (25 MHz, 24KB Program Flash, 512B Info Flash, 4KB SRAM, 2KB USB-RAM)
  • CC1101 with 433 MHz front-end
  • 32768 Hz can-type crystal attached to MSP430
  • TPS78225 LDO voltage regulator (2.5Vout, 150mA max)
  • 26 MHz SMD crystal attached to CC1101
  • (1) 574nm green LED

Here is the Schematic PDF. It appears to have been designed in EagleCAD, so you might want to contact TI if you use EagleCAD and would like to update the hardware.


  • The 5V USB power is dropped to 2.5V by the TPS78225, and thus it prevents operation above 20MHz. The TPS78230 would be a better choice, as it could allow reliable operation up to 25 MHz. The extra voltage is just being sunk by the LDO, anyway.
  • There is only a single LED. It is 574nm green and located on the same side of the board as the CC1101.
  • The 26MHz crystal is attached directly to the CC1101, and it must be bypassed onto XTAL2 of the MSP430 in order for USB to work. This requires that GDO2 is used permanently to drive the 26 MHz clock, and also that CC1101 is permanently kept in IDLE mode.
    • It would be a good choice to replace the 32768Hz can XTAL (which connects to XTAL1) with a 4MHz crystal attached to XTAL2, therefore also removing the GDO2-XTAL2 bypass currently in the design. Doing this will dramatically improve RF performance according to the CC1101 datasheet, which explicitly warns about driving GDOx with a clock signal during RX or TX (page 62, SWRS061G).
    • Using a 4MHz crystal on XTAL2 would also allow the CC1101 to go to sleep more easily, thereby improving the possibility of building a detachable USB stick with battery-backup.
    • Using a 4MHz crystal allows USB bootloading on other MSP430F55xx devices, which might be substituted.
    • XTAL1 is not imperative to the design. The internal REFOCLK is sufficient to use as a 32768Hz source.
  • Consider substituting the MSP430F5509 with MSP430F5510. The 5509 does not have enough Flash to run complex applications or support a non-volatile filesystem. Remember than the USB driver firmware consumes approximately 4KB. On this board, the program & data outlay of the PaLFI-Master demo app is ~21KB.

Firmware Overview

This board is official supported by the OpenTag Mainline Distribution, via the board file: board/msp430f5/board_RF430USB_5509.h. It is used specifically in the PaLFI demo app as the Master/Gateway.


  • The board support header and the CC1101 driver have special provisions to support this unusual hardware.
  • The Veelite filesystem must be used in mirror-only mode, due to the constrained Flash of the MSP430F5509 and the added requirement of the USB driver.
  • It is advised to use CCSv5, with CL430 4.x optimized for size, and COFFABI. This will generate the smallest code.
opentag/board/ez430-rf5509.txt · Last modified: 2012/07/10 21:07 by jpnorair