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CY4672 Reference Design Guide, Document # 001-16968 Revision ** 87
Bridge
5.3.7 Platform and Architecture Portability
The bridge firmware was designed to use the hardware features of the PRoC LP such as USB.
Porting the code to another microprocessor architecture may require modification of the existing
code to support the different processor specific features.
5.3.8 Initialization
The initialization of the PRoC LP chip is done by code that is generated in boot.asm by the PSoC
Designer software. The module
boot.asm calls main once the PRoC LP has been configured and ini-
tialized.
Main initializes the components of the bridge along with the radio modules. The bridge firmware
enters a loop to receive and handle radio packets and generate USB packets.
5.3.9 Wireless Protocol Data Payload
The RDK HID protocol has been optimized to reduce the ‘on time’ of the radio, which equates to
reduced power consumption on the LP devices. Refer to the RDK keyboard and RDK mouse sec-
tions for radio packet format details.
5.3.10 Suspend and Remote Wakeup
In order to meet the USBIF Compliance requirements regarding power consumption during suspend
state, the PRoC LP RDK bridge must reduce the over all power consumption to less than 500 µA if
Remote Wakeup is not enabled (Remote Wakeup is the device ability to wake up a suspended PC
with user’s input such as a key press, mouse movement, and others). Because the PRoC LP RDK is
not configured to wake up the suspended host PC, the entire bridge must go into deep sleep state to
conserve power. Only bus activity from the host PC can bring the bridge back to normal operation.
If Remote Wakeup is enabled, the bridge may draw up to 2.5 mA in suspend state. This requires that
the radio circuitry be off most of the time. It is necessary to periodically turn the radio on to sense
activity from the PRoC LP mouse or keyboard (and thereby know when to wake the host). The wake
up period is configurable and is set to 1 second (see Register OSC_CR0 setting). Increasing the
wakeup interrupt frequency results in a faster response to the user's wakeup events at the expense
of a slightly higher than average sleep current.
5.3.11 Interrupt Usage/Timing
The polling method is used for the Bind button.
Table 5-2. Bridge Average Icc in Suspend State
Parameter Icc Units
Bridge Average Suspend Power Consumption–REMOTE WAKE
UP ENABLED
1.44 mA
Bridge Average Suspend Power Consumption–REMOTE WAKE
UP DISABLED
0.3 mA
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