SP2-433-160 Datasheet, PDF (11/27 Pages) Radiometrix Ltd – UHF SpacePort Transceiver

3.0 SP2’S SWITCHES
SWITCHES is memory location 00h in RAM, it contains 8 flags which are used to determine the SP2's
operation. On SP2 reset, power-up or watchdog Time-Out it is loaded from location 08h (in EEPROM).
The default value is 00 hex - this is all functions deselected.
PS1 PS0 HTO RTO WE
7
6
5
4
3
ST LBT DBT
2
1
0
LBT & DBT - Collision Avoidance
LBT DBT Function
0 0 Immediate TX, no channel check
0 1 Fixed delay TX, no channel check
1 0 Immediate TX after channel clear
1 1 Random delay TX after channel clear
ST - Self Test Flag
WE - EEPROM Byte Write Enable
RTO - Radio Time Out
No Time Out
Time Out after > 2.9 S of plain preamble
HTO - Host Time Out
0 No Time Out
1 ^{Time Out if no reply from host after 2.9S}
PS1 & PS0 - Power Saving
PS1 PS0 Function
0 0 Continuous
0 1 Power Save
1 0 Sleep
1 1 Off
figure 11: Switches
3.1 PS0 & PS1 - POWER SAVING
The SP2 has 4 levels of power saving selected by PS0 & PS1 in SWITCHES. Power saving is achieved by
shutting down the Transceiver and the SP2 for a period of time (OFF-TIME) when the SP2 is in the Idle
state (i.e. nothing happening). During the OFF period current is reduced to the device leakage of <50 µA
typ. The SP2 will still respond immediately to a Host TX Request but cannot receive radio signals. After
the programmed OFF-TIME the SP2 will wake itself up, turn the receiver on and listen for valid
preamble. ON time = PWR->RX (EEPROM address 05h) + 2.5ms = 3.3ms (using SP2 Default values) If
preamble is found the SP2 will stay ON and decode the packet, if not
the SP2 will shut down for another OFF time period.
Also see - WAKE-UP (address 02h of EEPROM) and paragraph 2.3.2 .
Radiometrix Ltd, SP2 data sheet
page 11