Timing Parameters For Packet Detection; Detection Of Valid Wakeup Packets - Motorola M68HC08 Designer Reference Manual

Receiver Firmware
DRM055
36
Freescale Semiconductor, Inc.
For this short detection period, there is the possibility that the noise hit into the
RF front end would have a pattern like a packet portion. Therefore, if a packet
portion is detected, the MCU will turn on for a longer duty cycle. This duty cycle
is for receiving the next complete RF packet that can wake up the host.
The mechanism and the timing parameters for detecting a wakeup packet are
shown in Figure 7-7, Figure
TRANSMITTER
MOUSE PACKET
JB12 IRQ
JB12 WAKEUP
DUTY CYCLE
t : Length of one complete RF packet
PKT
t : Time interval of successive IRQ wakeup periods during device suspend.
IRQ
t : Duration of MCU being turned on in each IRQ wakeup period. MCU is turned
ON1
on in this period to detect a (portion of) RF packet has been received.
Figure 7-7. Timing Parameters for Packet Detection
TRANSMITTER
RF PACKET
MOUSE 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 turn on (t
ON1
for a longer time to detect a complete RF packet.
If one complete RF packet is received, the MCU will wake up the host.
Figure 7-8. Detection of Valid Wakeup Packets
Receiver Firmware
For More Information On This Product,
Go to: www.freescale.com
7-8, and Figure 7-9.
RF PACKET
t
PKT
t
IRQ
t
ON1
t
Sleep
RF PACKET
t
ON1
t
ON2
High Data Rate Wireless USB Optical Mouse Solution
NEXT MOUSE PACKET
VALID DATA DETECTED
JB12 WILL WAKE UP
THE HOST
)
ON2
MOTOROLA