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TS-5700 User's Manual
6 Digital I/O
There are 23 Digital Input/Output (DIO) lines available on the TS-5700. These are available on two headers
labeled DIO and LCD. In addition to the DIO signals, each header also has 5 Volt power and Ground available,
while the DIO header has an external reset available on pin 12 and IRQ6 in available on pin 13. The header
labeled LCD can be used as 11 DIO lines or as an alphanumeric LCD interface
DIO lines are arranged as byte-wide ports that can be programmed as either inputs or outputs in groups of 4-bits.
Four of the DIO lines are dedicated 0-5V swing outputs with high current drive capability. Two of these outputs
can sink or source 25 mA, while the other two can sink or source 100 mA.
The 5V power output pins on these headers have a 750 mA Poly-Fuse to prevent excessive current.
6.1 DIO Header
The DIO port provides +5V, GND, and 12 digital I/O lines that may be used to interface the
TS-5700 with a wide range of external devices. DIO lines DIO_0 thru DIO_7 are a byte-wide
port accessed at I/O location Hex 7E, while the 4 other DIO lines DIO_8 thru DIO_11 are
accessed in the lower 4 bits of I/O location Hex 7F. I/O location Hex 7D is a control port for
DIO. The direction of DIO lines DIO_0 thru DIO_3 is controlled by bit 0 of I/O location Hex
7D, and the direction of DIO_4 thru DIO_7 is controlled by bit 1 of I/O location Hex 7D. The
DIO_8 thru DIO_11 lines are always outputs. In all cases, when a control bit is a "1", it is
setting the corresponding DIO lines to be Outputs, while a "0" sets them to be Inputs. All
control bits at I/O location Hex 7D are initialized at reset to be "0".
The DIO_0 thru DIO_7 digital outputs on this port can source 4 mA or sink 8 mA and have
logic swings between 3.3V and ground. The digital inputs have standard TTL level
thresholds and must not be driven below 0 Volts or above 5.0 Volts. DIO lines DIO_0 thru
DIO_5 have 4.7KW pull-up resistors to 5V biasing these signals to a logic"1". DIO_6 and
DIO_7 are not biased and may float to either state when configured as Inputs, if not being actively driven.
DIO_10 and DIO_11 outputs have very high current drivers and can source or sink 100 mA each.
DIO_8 and DIO_9 outputs can source or sink 25 mA. DIO_8 thru DIO_11 all swing between 0 and 5V.
Pin 14 on the DIO header is connected directly to IRQ6 (also available on the PC/104 bus).
Pin 12 is an active low reset signal. It has a 4.7K pull-up resistor to 5V. A logic low on this signal will cause a
hard reset to the TS-5700 (same as a power cycle).
It is possible change the DIO_11 output so that it is driven by the Timer2 signal. The Timer2 signal has
historically been used to drive the speaker in a PC. The DIO_11 output has 100 mA source and sink drive
capability, so it could be used to directly drive a small 8 ohm speaker if a series capacitor is used to block the
DC component and a series resistor is added to reduce the power out. A 47 uF capacitor and a 27 ohm resistor
is a good starting point (adjust the resistor for volume).
If bit 2 at I/O location Hex 79 is set, Timer2 will drive the DIO_11 output (instead of bit 3 at I/O location Hex 7F).
Technologic Systems
11
http://embeddedARM.com/
(See Section
6.2). Most of the
Table 6.1 DIO Header
Pinout
5 V
16 15 DIO_7
IRQ6
14 13 DIO_6
Reset#
12 11 DIO_5
DIO_11 10 9
DIO_10 8
DIO_9
6
DIO_8
4
GND
2
5/2009
DIO_4
7
DIO_3
5
DIO_2
3
DIO_1
1
DIO_0
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