symmetrical configuration. We are poised to kick off a
Bluetooth mobile app that controls LEDs and a buzzer on
an associated piece of radio-equipped hardware.
The Anaren Multi-Sensor
Behold Photo 1. Everything hardware needed to
interface sensors and the touch screen of a smartphone is
shown in this overhead shot. Let’s take a closer look at the
component makeup of the Anaren multi-sensor
development kit. On the USB side of the dotted line in
Photo 2, we find an FTDI FT2232HL. The FT2232HL is a
dual-interface USB-to-whatever IC, with “whatever” being
bit-bang, JTAG, I2C, or SPI.
You can see the channel activity LED pairs directly
above and below the FT2232HL. At the top center of
Photo 2 lies the resident step-down switching regulator
(U9) which is based on a TI TPS62730. The resources of
the crystal to the upper left of the FT2232HL (Y2) belong
to the FT22232HL. U8 and U12 — which you see directly
below the FT2232 — are buffers that perform a logical
voltage translation between the FT2232HL and the
A20737A I/O pins.
Note the obvious absence of a microcontroller. This
implies that the “smarts” of the Bluetooth system resides
within the radio module. The logical design location of the
logic level converters (U8 and U12) tends to indicate that
the data buck stops at the radio. Another clue that there
may be a microcontroller under the bonnet of the radio is
the silkscreen associated with the I/O pin header positions.
Directly across the dotted line lies what at first glance
appears to be the monolith that the apes (and humans)
were attracted to in 2001: a Space Odyssey. Well, it’s
certainly not some sort of range extender or a ferrite bead
(more like a ferrite block). A bit of web research reveals
that the monolith you see prominently in Photo 3 is
actually a muRata buzzer. The trio of MOSFET drivers
(Q1, Q2, Q3) along one side of the buzzer drives an
integrated RGB (Red/Green/Blue) LCD module, which is
pictured in the lower right corner (D1). MOSFET Q4
drives the buzzer.
Moving in the direction of the radio module, the next
landmark we encounter is a digital joystick. The joystick is
not really a “joystick” in the analog sense, but a series of
four SPST switches (A, B, C, D) that are fired in the
rotation of the “stick.” The 24-pin QFN device nearest to
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ADVANCED TECHNIQUES FOR DESIGN ENGINEERS
; Photo 1. The Anaren Bluetooth development kit is built around the Anaren
A20737A Bluetooth module. This puppy is loaded with sensors that are easily
accessed via your smartphone.
; Screenshot 2.
plays a very
important part in
the behavior of
; Photo 2. The FTDI FT2232HL provides USB connectivity to
the multi-sensor development kit.
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