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5.6
External Control Software for RF Evaluation Mode
Software Overview
In the RF evaluation mode, the TRF4903 transmitter is controlled by external software run on a PC rather
than by the game/demo firmware installed on the MSP430. There is no operational link in RF evaluation
mode; the transmitter is set to one operational state at a time. Jumper JP2 sets the board operation mode
to game/demo or RF evaluation.
The RF control software has a graphical user interface (GUI) for the user to set the transmitter frequency,
power, etc. In the RF evaluation mode, the external software GUI controls the TRF4903 by passing control
register words through the computer COM1 serial port, RS232 driver IC (MAX3232), and finally through
the MSP430 microcontroller to the transmitter.
shows the graphical user interface that communicates with the circuit board through the COM1
RS232 serial port. The user must click on the adjacent COM1 button if its caption reads Com1 Closed in
order to open the serial port. The RF evaluation GUI is written in Borland C++ Builder, version 6, and
integrates utilities from Winsoft Ltd. to write to the serial port (Comport). In RF evaluation mode, the serial
port COM1 is used to control the TRF4903.
An example GUI setup for the TRF4903 (transmit mode) is shown in
. Several boxes and pick
lists have to be filled out by the user before clicking the Send All button to configure the RF transceiver.
Some of the boxes will toggle state when the cursor is placed over the box contents and double-clicked
(power amplifier).
The crystal frequency should be set to 19.6608 MHz. Set the reference divider to 48 (enter value and click
the Set button). The crystal tune capacitance should be set to an intermediate value like 17, 20, or 22 pF.
The charge pump current is 0.5 mA. In the Mode Select box, Either A-Word or B Word can be selected for
transmit mode. The phase-frequency detector reset should be set to Prescaler. Enter the power amp
output frequency and click the Set Freq button; the software rounds off the output frequency to an integer
multiple of the reference frequency. The Band Select List box can be used to select for the ISM band of
operation. The Modulation box should be set to FSK. For initial evaluation, set TXM=0 and TXDATA to
Low. The Multiplex Terminal List box can be used to define the output at terminal 16 of the TRF4903.
Other communication utilities such as HyperTerminal or ProComm can be used in place of the external
software GUI to control the TRF4903 in pass-through mode. Set the transmission raw data rate to
38.4 kbps, 8 bits data, no parity, 1 stop bit, no flow control or handshake. Send the 24-bit control words for
registers A through E in ASCII hex with a leading asterisk (hex 2A) and trailing carriage return (hex 0D),
i.e., “*[A][B][C][D][E]<CR>”.
TRF4903 With MSP430 Demonstration and Development Evaluation Kit
20
SWRU010A – October 2004 – Revised May 2005