
198
42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
Bit 1 – SLPTR - Multi-purpose Transceiver Control Bit
The bit SLPTR is a multi-functional bit to control transceiver state transitions.
Dependent on the radio transceiver state, a rising edge of bit SLPTR causes the
following state transitions: TRX_OFF => SLEEP (level sensitive), PLL_ON =>
BUSY_TX. Whereas the falling edge of bit SLPTR causes the following state transition:
SLEEP => TRX_OFF (level sensitive). When the radio transceiver is in TRX_OFF state
the microcontroller forces the transceiver to SLEEP by setting SLPTR = H. The
Transceiver awakes when the microcontroller releases the bit SLPTR. In states
PLL_ON and TX_ARET_ON, bit SLPTR is used as trigger input to initiate a TX
transaction. Here SLPTR is sensitive on rising edge only. After initiating a state change
by a rising edge at Bit SLPTR in radio transceiver states TRX_OFF, RX_ON or
RX_AACK_ON, the radio transceiver remains in the new state as long as the pin is
logical high and returns to the preceding state with the falling edge.
Bit 0 – TRXRST - Force Transceiver Reset
The RESET state is used to set back the state machine and to reset all registers of the
transceiver (except IRQ_MASK) to their default values. A reset forces the radio
transceiver into the TRX_OFF state and resets all transceiver register to their default
values. A reset is initiated with bit TRXRST = H. The bit is cleared automatically. During
transceiver reset the microcontroller has to set the radio transceiver control bit SLPTR
to the default value.
12.6.6 DRTRAM0 – Data Retention Configuration Register #0
Bit
7
6
5
4
3
2
1
0
NA ($135)
Res1
Res0
DRTSWOK ENDRT
DRTMP1 DRTMP0 DRTMN1 DRTMN0 DRTRAM0
Read/Write
R
RW
Initial Value
0
The DRTRAM0 register controls the behavior of SRAM block #0 (ATmega256RF block
#0 and #1 in parallel) in the power-states "power-save" and "power-down". To prevent
any data loss the SRAM will not completely disconnected from the power supply.
Reserved bits will be overwritten during chip reset by the factory calibration and should
not be modified.
Bit 7:6 – Res1:0 - Reserved
Bit 5 – DRTSWOK - DRT Switch OK
This bit indicates the status of the SRAM power-switch. A logical one indicates that the
SRAM supply voltage is fully available and the memory may be accessed normally.
Bit 4 – ENDRT - Enable SRAM Data Retention
During "Deep-Sleep" each SRAM block will either be switched off or provides data
retention of its memory content. This bit must set to one if data retention mode should
be used. Otherwise the SRAM is switched off (disconnected from the power supply)
and all its data are lost.
Bit 3:2 – DRTMP1:0 - Positive Data Retention Voltage Setting
The bits DRTMP1:0 define the reduction of the positive supply voltage during data
retention (DRT) mode. A preprogrammed calibration value is automatically written to
this register during chip reset, giving the factory value. The DRT mode must be enabled
by setting ENDRT high. Otherwise the SRAM is switched off (disconnected from the
power supply) and all its data are lost. The typical voltage reduction levels are shown in
the following table.