SN260 Datasheet, PDF (37/88 Pages) STMicroelectronics – ZigBee® 802.15.4 network processor

SN260
7.2.5
7.2.6
7.2.7
EmberZNet serial protocol
Power management
The SN260 will always idle its processor whenever possible. To further reduce power
consumption, the SN260 can be put to sleep by the Host. In power down mode, only an
external interrupt will wake the SN260. In deep sleep mode, the SN260 will use its internal
timer to wake up for scheduled events. The SN260 provides two independent timers that the
Host can use for any purpose, including waking up the SN260 from deep sleep mode.
Timers are set using the setTimer command and generate timerHandler callbacks.
The initial frame control byte of every command tells the SN260 which sleep mode to enter
after it has responded to the command. Including this information in every command
(instead of having a separate power management command) allows the SN260 to be put to
sleep faster. If the Host needs to put the SN260 to sleep without also performing another
action, the nop command can be used.
In deep sleep mode, the SN260 will wake up for an internal event. If the event does not
produce a callback for the Host, the SN260 will go back to sleep once the event has been
handled. If the event does produce a callback, the SN260 will signal the Host and remain
awake waiting for the callback command. If the frame control byte of the callback
command specifies deep sleep mode, then the SN260 would normally go back to sleep after
responding with the callback. However, if there is a second callback pending, the SN260 will
remain awake waiting for another callback command.
To avoid disrupting the operation of the network, only put the SN260 to sleep when it is not
joined to a network or when it is joined as a sleeping end device. If the SN260 is joined as a
sleeping end device, then it must poll its parent in order to receive messages. The Host
controls the polling behavior using the pollForData command. Polls are sent periodically
with the interval set by the Host or a single poll can be sent. The result of every poll attempt
is optionally reported using the pollCompleteHandler callback.
Tokens
Some of the non-volatile storage on the SN260 is made available for use by the Host. Up to
8 manufacturing tokens stored in the flash information area can be read using the
getMfgToken command and up to 8 tokens stored in the simulated EEPROM can be read
and written using the setToken and getToken commands. Each token is 8 bytes. Tokens
preserve their values between reboots. Refer to section Simulated EEPROM for a
description of the simulated EEPROM and write cycle estimates.
RAM
Some of the RAM on the SN260 can be reserved by the Host for its own use. The amount of
space reserved is the EZSP_CONFIG_HOST_RAM configuration value (set using the
setConfigurationValue command). The Host can then read and write data using the
setRam and getRam commands. If the Host chooses to reserve RAM, this will reduce the
number of messages and callbacks that the SN260 can buffer.
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