Rainbow Electronics AT86RF231 - Manual (Page 122)

122
8111A–AVR–05/08
AT86RF231
If the PLL operates for a long time on the same channel, e.g. more than 5 min, or the operating
temperature changes significantly, it is recommended to initiate the calibration loops manually.
Both calibration loops can be initiated manually by setting PLL_CF_START = 1 (register 0x1A,
PLL_CF) and register bit PLL_DCU_START = 1 (register 0x1B, PLL_DCU). To start the calibra-
tion the device must be in PLL_ON or RX_ON state. The completion of the center frequency
tuning is indicated by a PLL_LOCK interrupt.
Both calibration loops may be run simultaneously.
9.7.5 Interrupt Handling
Two different interrupts indicate the PLL status (refer to register 0x0F). IRQ_0 (PLL_LOCK) indi-
cates that the PLL has locked. IRQ_1 (PLL_UNLOCK) interrupt indicates an unexpected unlock
condition. A PLL_LOCK interrupt clears any preceding PLL_UNLOCK interrupt automatically
and vice versa.
A PLL_LOCK interrupt is supposed to occur in the following situations:
• State change from TRX_OFF to PLL_ON / RX_ON
• Channel change in states PLL_ON / RX_ON
Any other occurrences of PLL interrupts indicate erroneous behavior and require checking of the
actual device status.
The state transition from BUSY_TX to PLL_ON after successful transmission does not generate
an IRQ_0 (PLL_LOCK) within the settling period.
9.7.6 Register Description
Register 0x08 (PHY_CC_CCA):
This register sets the IEEE 802.15.4 - 2.4 GHz channel number
• Bit 7 - CCA_REQUEST
Refer to Section 8.5 “Clear Channel Assessment (CCA)” on page 94 .
• Bit [6:5] - CCA_MODE
Refer to Section 8.5 “Clear Channel Assessment (CCA)” on page 94 .
• Bit [4:0] - CHANNEL
The register bits CHANNEL define the RX/TX channel. The channel assignment is according to
IEEE 802.15.4.
Bit 7 6 5 4 3 2 1 0
+0x08 CCA_REQUEST CCA_MODE CHANEL PHY_CC_CCA
Read/Write W R/W R/W R/W R/W R/W R/W R/W
Reset Value 0 0 1 0 1 0 1 1