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Demo Examples
9.6
Demo 6: Trimming the TMS37157 Target Board
This demo shows how to trim the TMS37157 target board, which is required if a different antenna is used.
The trimming of the TMS37157 target board is done by the MSP430 via the SPI interface. The trimming
procedure is implemented in the MSP430 firmware.
To determine if trimming is necessary:
1. In the Direct Access Mode tab, read page 2 (see
Figure 29
).
2. If the TMS37157 is already trimmed, the content of the Page 2 is 0x01.
Figure 29. Demo 6 - Read Page 2
To activate the trimming process:
1. Program Page 2 with the value 00 (see
Figure 30
).
2. After programming, in the Received Byte field, the content of Page 2 is 00.
3. Connect the new antenna.
4. Connect the battery board to the target board.
5. Set the jumper on the battery board to supply the TMS37157.
6. Press the Push Button on the target board.
The green and red LEDs turn on.
7. Wait while the red LED turns off and the green LED flashes.
8. Trimming is complete when the green LED turns off.
After the trimming, use the Read Page command to verify that the content of Page 2 is 0x01.
The variation of the resonance circuit should be in the range of
±
2 kHz and the quality factor of the
antenna should be approximately 60 (see
SWRS083
).
29
SLAU281B
–
November 2009
–
Revised March 2010
eZ430-TMS37157 Development Tool
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Copyright
©
2009
–
2010, Texas Instruments Incorporated
