4 Digital I/O
There are 20 Digital Input/Output (DIO) lines available on the TS-7200. These are
available on two headers labeled “DIO” and “LCD”. The header labeled LCD can be
used as 11 DIO lines or as an alphanumeric LCD interface (
See Section 4.2
). The
header labeled DIO has 9 DIO pins available. In addition to the DIO signals, each
header also has a power pin and Ground available. The LCD header has 5V power
available while the DIO header has 3.3V power.
Three pins on the DIO header are used to bring out the EP9302 SPI bus. By using
some of the DIO pins as peripheral Chip Select signals, a complete interface is
available for SPI peripherals. It is also possible to bring out a fourth SPI bus function
[SPI_Frame] by adding a 10 ohm resistor in the position labeled R1 on TS-7200 RevB
boards. This signal is not required for many SPI peripherals but it may prove useful in
some applications.
All of the DIO lines are programmable as either inputs or outputs and the direction of
each I/O pin can be individually programmed. All DIO control registers are 8-bits wide
and aligned on word (32-bit) boundaries. For all registers, the upper 24 bits are not
modified when written and are always read back as zeros. Every DIO pin has two
registers used to access it, an 8-bit data register and an 8-bit data direction register
(DDR). The DDR controls whether each DIO pin is an input or an output (”1” = output).
Writing to the data register only affects pins that are configured as outputs. Reading the
data register always returns the state of the DIO pin.
Many of the DIO pins (DIO_0 thru DIO_8 and LCD_0 thru LCD_7) can also be
programmed to cause interrupts. The interrupt properties of these pins are individually
configurable -- each interrupt can be either high or low level sensitive or either rising or
falling edge triggered. It is also possible to enable debouncing on any of these
interrupts. Debouncing is implemented using a 2-bit shift register clocked by a 128 Hz
clock.
Download the EP9301 User Manual
and see Chapter 21 for details.
The TS-7200 RevB boards also allow access to two 12-bit A/D channels on the DIO
header.
The 5V power output pin on the LCD header has a 750 mA Poly-Fuse to prevent
excessive current. The 3.3V power on the DIO header is current limited to
approximately 1 Amp by an LM1117 3.3V regulator.
TS-7200 User's Manual
Technologic Systems
http://www.embeddedARM.com/
13
12/2004
Summary of Contents for TS-7200
Page 1: ...TS 7200 User s Manual...