TDP-P75
Service Manual
the DDP2000 to place specific data on each pin.
The recommended operating conditions for these signals are given in section 2 and
include the following:
Sink current: 4 mA maximum
Source Current: 4 mA maximum
4.7.10.
Peripherals Used in the Reference Design
The list of peripherals that are demonstrated in the reference design is as follows:
....
Fans and Blowers (GPIO, PWM)
....
Temperature sensors (GPIO and I
2
C)
....
Infra-red sensors for remote controls (dedicated I/O)
....
Keypad for user inputs (GPIO)
....
Power monitor circuitry (dedicated power sensor signal)
....
In-Circuit Emulator (JTAG)
....
RS-232 (UART)
4.7.11.
Fans and Blowers
Fan and blowers are used to regulate the temperature within the projector housing.
Simple units are only electrically connected to an appropriate power source. However,
more sophisticated operation can be achieved by varying the voltage to the fan.
The TI reference design contains an example of how to use a PWM signal from the
DDP2000 to pulse width modulate the fan input power. With this technique the average
input voltage to the fan can be regulated to be between 0% and 100% of the available
power.
Also, in this example, an output of the fan which indicates the fan is not rotating is routed
to a GPIO line.
4.7.12. Temperature
Sensors
Temperature sensors can be located in key locations inside the projector and provide
feedback to the processor or the user. The system designer can choose to connect these
sensors via GPIO or I2C
In the reference design, TI has chosen a bimetal switch to indicate a lamp over
temperature condition to the DDP2000 via a GPIO signal.
4.7.13. Infra-red
Sensors
The DDP2000 ASIC has two ports dedicated to IR sensor controls. Serial data from each
of the IR ports is routed to the DDP2000 ASIC.
4.7.14.
Keypad for user inputs (GPIO)
In the TI reference design 6 GPIO signals are used to monitor the keypad.
4.7.15.
ARM In-Circuit Emulator
In the reference design a 20 pin connector is provided for the ARM in-circuit emulator.
This is useful for software integration but is not expected to be on the product design.
Please see the TI reference design for connectivity.
4.7.16.
ARM Embedded Trace
In the reference design a 38 pin connector is provided for the ARM Embedded Trace
function. This is useful for software integration but is not expected to be on the product
design. Please see the TI reference design for connectivity.
4.7.17. RS-232
In the TI reference design, one of the two UARTs from the DDP2000 is used as an RS-232
port. This usage requires a level shifter, TI has chosen a Max3232 for the reference
design, as well as a standard 9 pin serial connector.
Figure 1. Input Board
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