CYW20734
1.13 Shutter Control for 3D Glasses
The CYW20734, combined with the Cypress Bluetooth host device, provides full system support for 3D glasses on televisions. The
Cypress Bluetooth host device gets frame synchronization signals from the TV, converts them into proprietary timing control
messages, then passes the messages to the CYW20734. The CYW20734 uses these messages to synchronize the shutter control
for the 3D glasses with the television frames.
The CYW20734 can provide up to four synchronized control signals for left and right eye shutter control. These four lines can output
pulses with microsecond resolution for on and off timing. The total cycle time can be set for any period up to 65535 msec. The pulses
are synchronized to each other for left and right eye shutters.
The CYW20734 seamlessly adjusts the timing of the control signals based on control messages from the Cypress Bluetooth host
device, ensuring that the 3D glasses remain synchronized to the TV display frame.
3D hardware control on the CYW20734 works independently of the rest of the system. The CYW20734 negotiates sniff with the
Cypress Bluetooth host device and, except for sniff resynchronization periods, most of the CYW20734 circuitry remains in a low power
state while the 3D glasses subsystem continues to provide shutter timing and control pulses. This significantly reduces total system
power consumption.
1.14 Triac Control
The CYW20734 includes hardware support for zero-crossing detection and trigger control for up to four triacs. The CYW20734 detects
zero-crossing on the AC zero detection line and uses that to provide a pulse that is offset from the zero crossing. This allows the
CYW20734 to be used in dimmer applications, as well as any other applications that require a control signal that is offset from an
input event.
The zero-crossing hardware includes an option to suppress glitches.
1.15 Serial Peripheral Interface
The CYW20734 has two independent SPI interfaces. One is a master-only interface (SPI_2) and the other (SPI_1) can be either a
master or a slave. Each interface has a 64-byte transmit buffer and a 64-byte receive buffer. To support more flexibility for user
applications, the CYW20734 has optional I/O ports that can be configured individually and separately for each functional pin. The
CYW20734 acts as an SPI master device that supports 1.8V or 3.3V SPI slaves. The CYW20734 can also act as an SPI slave device
that supports a 1.8V or 3.3V SPI master.
Note: SPI voltage depends on VDDO/VDDM; therefore, it defines the type of devices that can be supported.
1.16 Infrared Modulator
The CYW20734 includes hardware support for infrared TX. The hardware can transmit both modulated and unmodulated waveforms.
For modulated waveforms, hardware inserts the desired carrier frequency into all IR transmissions. IR TX can be sourced from
firmware-supplied descriptors, a programmable bit, or the peripheral UART transmitter.
If descriptors are used, they include IR on/off state and the duration between 1–32767 µsec. The CYW20734 IR TX firmware driver
inserts this information in a hardware FIFO and makes sure that all descriptors are played out without a glitch due to underrun (see
Figure 6).
Figure 6. Infrared TX
Document Number: 002-14874 Rev. *S
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