anyone, and is supplied by FTDI. As you can see in
Photo 1, the VM800B50A EVE development unit is
ready for installation, and comes complete with a
bezel.
Driver Hardware
I will take you through each and every step
necessary to bring our FT800 and LCD panel to life.
The first order of business is to find out what the EVE
unit requires as far as a hardware interface. Take a
look at Photo 2. Note the absence of any I2C signals.
That’s because the development kit design ties the
FT800’s MODE pin to GND which enables SPI mode
on the FT800’s MCU interface. The USB connector
does not carry any USB signals and is used to
alternately supply 5.0 volt power to the EVE
development environment. We will use the 10-pin
male header to provide 3. 3 volt power, as well as the
SPI signals.
We could easily drive the FT800 with a Microchip
enhanced mid-range microcontroller such as the
PIC16F1829. A PIC18F microcontroller would fit
nicely here, as well. This time around, we’re going to
change it up and use a PIC32MX device. We don’t
need native USB or CAN support. We also don’t
need large amounts of SRAM. So, we can choose a
relatively “small” 32-bit PIC32MX microcontroller.
Rather than reinvent the wheel, let’s choose an
off-the-shelf PIC32MX platform that meets our
requirements.
The Digilent chipKIT MX3 shown in Photo 3 will
do nicely. The chipKIT MX3 is hosted by a
PIC32MX320F128H. The chipKIT MX3’s 32-bit MCU
natively supports an SPI portal and a number of
external interrupt pins. There are ample idle GPIO
pins to service the FT800’s PD# pin, as well as any
other GPIO-oriented task we may have to undertake.
If you wish to take a look at the entire chipKIT MX3
hardware configuration, you can download the
schematic and user’s manual from the Digilent site
( www.digilentinc.com).
The chipKIT MX3 was originally designed to
ADVANCED TECHNIQUES FOR DESIGN ENGINEERS
June 2014 69
■ Photo 1. Everything we need to succeed is in this
package. In addition to the FT800, this EVE
development environment includes a 3. 3 volt LDO
voltage regulator, level shifters for 5.0 volt tolerance
on the MCU interface, an audio subsystem, a 12 MHz
crystal, and a 5.0 inch touch-enabled LCD panel.
■ Photo 2. There are no I2C interface pins as the FT800's MODE
pin is tied to GND which enables SPI mode on the FT800's
MCU interface.
■ Photo 3. The chipKIT MX3 was originally designed
to accommodate Digilent's line of Pmods. However,
the compact and logical layout of the MX3's GPIO
pins makes this little board perfect for our EVE needs.
