Power Consideration; Id Updating Process; Jb12 Rejecting Packet-Like Noise To Prevent False Wakeup - Motorola M68HC08 Designer Reference Manual

7.3.2 Power Consideration

7.4 ID Updating Process

High Data Rate Wireless USB Optical Mouse Solution
MOTOROLA
Freescale Semiconductor, Inc.
RECEIVER RF
FRONT END
NOISE SIMILAR TO
PORTION OF PACKET
JB12 IRQ
JB12 WAKEUP
DUTY CYCLE
PORTION OF
PACKET DETECTED
If during a t period a portion of a RF packet is detected, the RF receiver will be
ON1
turned on (t ) for a longer time to detect a complete RF packet.
ON2
If the receiver does not receive a complete RF packet, the MCU/receiver will sleep again.
If the receiver receives a complete RF packet, the MCU/receiver will wakeup the host.
Figure 7-9. JB12 Rejecting Packet-Like Noise to Prevent False Wakeup
The average power consumption during suspend is given by the following
equation:
P x t
ON
P =
Average
Power consumption can be decreased by increasing t
than t the receiver may not catch the incoming RF packet. Therefore,
PKT
choosing t equal to t
IRQ
Another way for reducing power consumption is to shorten t
be too small in practice. Otherwise, the false wakeup for 2nd stage complete
packet detection can occur more frequently resulting in more power being
actually consumed (refer to
fine-tuned in the actual application system.
The user must following these steps to update the mouse ID:
1. Press and hold the "PTA0" button in the receiver
2. Press the "CONNECT" button once in the mouse
3. Release the "PTA0" button in the receiver
Once these steps are complete, the new mouse ID will be updated in the
receiver.
Receiver Firmware
For More Information On This Product,
Go to: www.freescale.com
RANDOM NOISE
t
ON1
t
ON2
NO VALID DATA
DETECTED
+ P x (t – t
ON Sleep IRQ ON
t
IRQ
could be an optimizing value for t
PKT
Figure 7-9). Note that this parameter can be
Receiver Firmware
ID Updating Process
SLEEP AGAIN
)
But, if t is larger
IRQ. IRQ
.
IRQ
. But, t cannot
ON ON
DRM055
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