Rainbow Electronics AT86RF231 - Manual (Page 145)

145
8111A–AVR–05/08
AT86RF231
Note: If ANT_DIV_EN = 1 register bit ANT_EXT_SW_EN shall be set to 1, too.
• Bit 2 - ANT_EXT_SW_EN
If enabled, pin 9 (DIG1) and pin 10 (DIG2) become output pins and provide a differential control
signal for an Antenna Diversity switch. The selection of a specific antenna is done either by the
automated Antenna Diversity algorithm (ANT_DIV_EN = 1), or according to register bits
ANT_CTRL if Antenna Diversity algorithm is disabled.
Do not enable Antenna Diversity RF switch control (ANT_EXT_SW_EN = 1) and RX Frame
Time Stamping (IRQ_2_EXT_EN = 1) at the same time, see
Section 11.6 “RX Frame Time
Stamping” on page 150 .
If the register bit is set the control pins DIG1/DIG2 are activated in all radio transceiver states as
long as register bit ANT_EXT_SW_EN is set. If the AT86RF231 is not in a receive or transmit
state, it is recommended to disable register bit ANT_EXT_SW_EN to reduce the power con-
sumption or avoid leakage current of an external RF switch, especially during SLEEP state. If
register bit ANT_EXT_SW_EN = 0, output pins DIG1 and DIG2 are pulled-down to digital
ground.
Note: If ANT_DIV_EN = 1 register bit ANT_EXT_SW_EN shall be set to 1, too.
• Bit [1:0] - ANT_CTRL
These register bits provide a static control of an Antenna Diversity switch. Setting
ANT_DIV_EN = 0 (Antenna Diversity disabled), this register setting defines the selected
antenna.
Table 11-12. Antenna Diversity Control
Register Bit Value Description
ANT_DIV_EN 0 Antenna Diversity algorithm disabled
1 Antenna Diversity algorithm enabled
Table 11-13. Antenna Diversity RF Switch Enable
Register Bit Value Description
ANT_EXT_SW_EN 0 Antenna Diversity RF Switch Control disabled
1 Antenna Diversity RF Switch Control enabled