Cypress CY4672 manual Suspend and Remote Wakeup, Interrupt Usage/Timing, Parameter Icc Units

Bridge

5.3.7Platform 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.

5.3.8Initialization

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.

5.3.9Wireless 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.

5.3.10Suspend 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.

Table 5-2. Bridge Average Icc in Suspend State

Parameter	Icc	Units
Bridge Average Suspend Power Consumption–REMOTE WAKE	1.44	mA
UP ENABLED
Bridge Average Suspend Power Consumption–REMOTE WAKE	0.3	mA
UP DISABLED

5.3.11 Interrupt Usage/Timing

The polling method is used for the Bind button.

CY4672 Reference Design Guide, Document # 001-16968 Revision ** 87

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