April
2005, Issue 177
Simple
USB Data Acquisition
LPC2138
MCU
The
LPC2138 is one of Philips’s newest ARM-based microcontrollers.
Having previously designed with the LPC2106, the LPC2138
piqued my interest given its vast assortment of added
peripherals. The addition of ADCs, DACs converters,
an external memory controller, and edge-sensitive interrupts
made it the perfect migration part for my LPC2106 designs
(see Figure 2).
|
(Click
here to enlarge)
|
Figure
2—A 32-bit ARM7 core lies at the heart of the LPC2138.
Given the chip’s high-performance core and numerous
peripherals, it can cover a vast number of applications. |
The
small LPC2138 contains everything but the kitchen sink.
In addition to a ton of peripherals and general-purpose
I/O, it’s loaded with 512 KB of flash memory (128 bits
wide for high speed) and 32 KB of RAM—definitely not
the typical memory sizes I’m used to seeing in plain-vanilla
8-bit microcontrollers. Another remarkable feature is
the chip’s size. The 64-pin QFP part measures in at
10 mm × 10 mm, making it perfect for tightly spaced
applications.
And
then, of course, there’s the one thing that makes this
microcontroller shine: an ARM 32-bit ARM7TDMI-S core.
This 32-bit ARM core yields 54 MIPS when running at
60 MHz, which is easily achieved by utilizing the LPC2138’s
on-board PLL. So, not only do you get a vast number
of peripherals and tons of memory, you get all the benefits
of using an ARM core! What are the benefits, you ask?
An obvious one is its high performance and low-power
consumption combination. Others are its vast software
tool support, real-time debugging, and code density
options (Thumb) for high-volume applications with memory
restrictions.
The
ARM core definitely has found its way into numerous
applications via microprocessors, ASICs, SoCs, and FPGAs.
And now, with its growing use in cost-effective microcontrollers,
I may think twice before choosing a performance-limited
8-bit microcontroller for my next application. Either
way, if you’re into embedded design, there’s no doubt
that having ARM experience under your belt would be
beneficial to your career. ARM is an interesting and
detailed topic in and of itself. Refer to the Resources
section of this article for more information.
I
hope I’ve piqued your interest in the LPC2138. Now let’s
examine how the LPC2138 fits into the USB ARM data acquisition
(DAQ) design.
