AT86RF230_09 ATMEL [ATMEL Corporation], AT86RF230_09 Datasheet - Page 69

• Manufacturer Part Number: AT86RF230_09
• Description: Low Power 2.4 GHz Transceiver for ZigBee, IEEE 802.15.4, 6LoWPAN, RF4CE and ISM
• Manufacturer: ATMEL [ATMEL Corporation]

9.6.5 Register Description
5131E-MCU Wireless-02/09
Bit
0x03
Read/Write
Reset value
Bit
0x03
Read/Write
Reset value
To reduce power consumption and spurious emissions, it is recommended to turn off
the CLKM clock when not in use or to reduce its driver strength to a minimum, refer to
section 4.3.
Note:
During reset procedure, see section 7.1.4.2, register bits CLKM_CTRL are shadowed.
Although the clock setting of CLKM remains after reset, a read access to register bits
CLKM_CTRL delivers the reset value 1. For that reason it is recommended to write the
previous configuration (before reset) to the CLKM_CTRL to align the radio transceiver
behavior and register configuration. Otherwise the CLKM clock rate is set back to the
reset value (1 MHz) after the next SLEEP cycle.
For example if the CLKM clock rate is configured to 16 MHz the CLKM rate remains at
16 MHz after a reset, however the register bits CLKM_CTRL are set back to 1. Since
CLKM_SHA_SEL reset value is 1, the CLKM clock rate would change to 1 MHz after
the next SLEEP cycle if the CLKM_CTRL setting is not updated.
Register 0x03 (TRX_CTRL_0)
The TRX_CTRL_0 register controls the drive current of the digital output pads and the
CLKM clock rate.
• Bit [7:6] – PAD_IO
Refer to in section 4.3.3.
• Bit [5:6] – PAD_IO_CLKM
The register bits PAD_IO_CLKM set the output driver current of pin CLKM.
Table 9-9. CLKM Driver Strength
• Bit 3 – CLKM_SHA_SEL
The register bit CLKM_SHA_SEL defines the commencement of the CLKM clock rate
modifications when changing register bits CLKM_CTRL.
Table 9-10. Commencement of CLKM Clock Rate Modification
Register Bit
PAD_IO_CLKM
Register Bit
CLKM_SHA_SEL
CLKM_SHA_SEL
R/W
R/W
7
0
3
1
PAD_IO
Value
Value
0
1
2
3
0
R/W
R/W
6
0
2
0
Description
2 mA
4 mA
6 mA
8 mA
Description
CLKM clock rate changes immediately
CLKM_CTRL
R/W
R/W
5
0
1
0
PAD_IO_CLKM
R/W
R/W
AT86RF230
4
1
0
1
TRX_CTRL_0
TRX_CTRL_0
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