Toshiba TDP-D1 Service Manual page 91

Microprocessor
Items that support the Microprocessor include:
  General Purpose I/O (GPIO)
  D ecoded Chip Select (CS)

  E xternal Interrupts

  I nfrared (IR) Receivers

  U niversal Asynchronous Receiver Transmitter (UART)

General Purpose I/O (GPIO)
GPIO port pins can be used to implement a keypad interface and other general control functions.
Pixelworks recommends using Port A0 and Port A1 as the default 2-wire serial bus. The GPIO ports
are not 5V tolerant. Care should be taken to protect these pins from 5V inputs. GPIO outputs are
3.3V CMOS. These pins have 4mA output drivers. Therefore, they are not recommended to be used
to directly drive LEDs or other high-current devices.
Chip Select—I/O Expansion and Other
Decoded Chip Selects (CS) are available to allow interfacing to additional external devices on
the ImageProcessor bus. You can easily add additional GPIOs by using the CS line with an 8-bit
latch or buffer, as shown in Figure 6. The processor bus is not 5V tolerant, so 3.3V devices or buffers
must be used.
Figure 6. I/O Expansion Examples
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