User manual

4D SYSTEMS Armadillo-43(T) – Linux based Computer Display Module
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Armadillo-43(T) – Linux based Computer Display Module
be ‘taken over’ by the audio system, if audio is
started, such as playing a movie.
Please refer to section 5.7 “Audio – On Board and
External” for more information on using the PWM
for audio.
Special PWM 5.5.
4D Systems has developed a driver for the
Armadillo which has the ability to clock most of
the GPIO with a PWM clock generated by the
unused PCM clock on the BCM2835, coupled with
DMA.
One of these pins is allocated to the Backlight, to
allow the backlight to be dimmed. Please refer to
the “TFT LCD Display Backlight” section for more
information.
In regards to the additional PWMs, an Application
Note will be made available to detail how to use
these, and what the limitations are. This will be
available on the 4D Systems website, Application
Note page.
Serial UART 5.6.
There are two GPIO which by default are
configured to be a Serial UART. These can be used
as GPIO instead if required.
The signals can be found on the following pins:
Header
GPIO Number
Signal Name
H2 Pin 7
GPIO33
RX0
H2 Pin 8
GPIO32
TX0
This Serial UART can be used to log into the
Armadillo using a serial console application, an
example is Putty. By default the Baud Rate to do
this is 115200. This Serial UART can also be used
for many applications by the User. Some require
control to be removed from Linux so the Serial
UART can be used by the User or the Users
scripts/applications.
Please refer to the “How To” section, and the area
titled “Setting the Serial UART for User Control”.
The Serial port will no longer be used by Linux and
therefore you will no longer be able to log into the
Armadillo using the Serial UART, however this does
now allow your scripts/applications to use the
Serial UART instead.
Audio – On Board and External 5.7.
The Armadillo features an on board amplifier and
tiny speaker, which are connected to the line out
pin which is present on the H2 header.
The on board speaker is small and designed only to
provide a small level of audio capability to the
display module. If the audio level is raised too high
in software, it can cause the output to distort and
become inaudible. The on-board audio capability
of the Armadillo is mono only, and features only a
single (mono) line out signal.
If a more capable audio system is desired to be
connected to the line out signal, the on board
amplifier and speaker can be disabled, and an
external amplifier can be connected to the H2
Header, which would enable a more powerful
audio system to be connected.
If Stereo or better audio is required, both PWM
signals are available on the H2 header, and with
appropriate external filtering circuitry, a more
capable stereo audio system could be created
using these 2 signals. Alternatively, a USB
Soundcard can be connected to the Armadillo.
To disable, enable or control the on-board
amplifier with a GPIO, there is a 3 pin male jumper
header titled JP2, to the left of the speaker, above
the Display flex connector. Please refer to Section
3, “Pin Configuration and Summary” and the table
pertaining to “JP2 Jumper Header” for more
information on this Jumper and its settings.
Resistive Touch Screen 5.8.
The resistive touch screen on the Armadillo-43T is
a 4-wire variety, and interfaces to the BCM2835
SoC via a Microchip AR1021 resistive touch
controller, using the I2C0 bus.
A driver has been provided by Microchip for this
device, which has been integrated into the Kernel
shipped with the 4D Systems Raspbian Image,
which enables the resistive touch controller to be
used.
Inside the modified Kernel which is provided in the
4D Systems Raspbian Image, is a modified I2C
driver which directs the I2C channels to the
appropriate pins, for use by the AR1021 driver.
Calibration of the Resistive Touch is described in
the How To section.