
190
42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
Figure 12-2 shows the chained startup procedure after power up. The Figure 12-3
shows the startup from DEEP_SLEEP. A module is only switched on if it is not
deselected by power reduction register (PRR1 or PRR2). This is possible for SRAM
blocks and radio transceiver power switch. At the end of the startup, the pin RSTON is
enabled. Depending of the currently enabled memory blocks (NSRAM), the startup
procedure takes different time.
tSTARTUP_TOTAL = tBG + tDVREG + NSRAMtDRT_ON + 3tPWRSW_ON + tOSC_STARTUP
The SRAM is organized in 4kByte blocks, the NVM in 128kByte blocks. Deselected
SRAM blocks (by PRR2 register) reduce the wakeup time from DEEP_SLEEP. For
Figure 12-2. Timing visualization of power up
s t a r t u p
b a n d g a p
s t a r t u p
D V R E G
D R T s w i t c h
S R A M # 0
P O R
D R T s w it c h
S R A M # 1
D R T s w i t c h
S R A M # 2
D R T s w it c h
S R A M # 3
p o w e r s w i t c h
r a d i o t r a n s .
p o w e r s w i t c h
N V M
o s c il l a t o r
s t a r t u p
t P O R
t B G
t D V R E G
t D R T _ O N
t P W R S W _ O N
t O S C _ S T A R T U P
R S T O N
t S T A R T U P
Figure 12-3. Timing visualization of wakeup from DEEP_SLEEP
s t a r t u p
b a n d g a p
s t a r t u p
D V R E G
D R T s w it c h
S R A M # 0
S L E E P
D R T s w i t c h
S R A M # 1
D R T s w i t c h
S R A M # 2
D R T s w i t c h
S R A M # 3
p o w e r s w it c h
r a d i o t r a n s .
p o w e r s w i t c h
N V M
o s c il l a t o r
s t a r t u p
t B G
t D V R E G
t D R T _ O N
t P W R S W _ O N
t O S C _ S T A R T U P
t S T A R T U P
Sleep
Six sleep modes are defined for the CPU. Disabling the power-chain and thus switching
off of the above mentioned blocks makes only sense for the modes “power-down” and
“power-save”. Also an enabled radio transceiver prevents the power-chain from being
disabled.
In order to disable the power-chain, one of the following conditions must fit:
The radio transceiver has to be disabled (power reduction register PRR1 bit
PRTRX24).
The radio transceiver is sent into SLEEP mode (register TRXPR bit SLPTR).
The SRAM blocks may be configured separately to decrease their leakage current (see
The following table shows the different implemented sleep modes and the behavior of
the power-chain depending on the current state of the radio transceiver.
Table 12-2. Power states of microcontroller and radio transceiver
AVR State
Radio Transceiver State
Powerchain
ON
off (SLEEP or power reduction)
ON
off
(1…6)
ON
off
(1,4…6)
off (SLEEP or power reduction)
ON