User's Manual

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M2x40 Mote Datasheet Dust Networks™ 10
Vcc Inrush Current (Power On with Supply Impedance of 1 Ohm)
0
250
500
750
1000
0 50 100 150 200 250
Time (us)
Current (mA)
Figure 4 V
CC
Inrush Current
7.3 Serial Interface Boot Up
7.3.1 M2x40 Serial Interface Boot Up
Upon M2x40 power up, the MT_CTS
¯¯¯¯¯¯¯
line is high (inactive). The M2x40 serial interface boots within boot_delay (see Error!
Reference source not found.) of the mote powering up, at which time the M2x40 will transmit an HDLC Mote Information
packet. Note that full handshake (see section 8.3.2) is in effect and is required to receive this packet.
8.0 Interfaces
8.1 Timestamps
The M2x40 has the ability to deliver network-wide synchronized timestamps. The M2x40 sends a time packet (as described
in Error! Reference source not found.) through its serial interface when one of the following occurs:
• Mote receives an HDLC Get Parameter request for time/state (see Error! Reference source not found.)
• On the M2x40, mote TIME
¯¯¯¯
signal is activated
The TIME
¯¯¯¯
pin is optional and has the advantage of being more accurate. The value of the timestamp is taken within
approximately 1 ms of receiving a TIME
¯¯¯¯
signal activation. If the HDLC request is used, because of packet processing, the
value of the timestamp may be captured several milliseconds after receipt of the packet. The real time delivered to the sensor
processor is relative to the real time clock on the Manager, which serves as the Network Real Time Clock (NRTC). The time
stamp skew across the network is guaranteed to be within ±250 ms of the NRTC.
Figure 5 Network Real Time Clock
When the time pin is activated for at least min_strobe_length (see Error! Reference source not found.), the mote responds
by sending the time packet within 100 ms delay.