May
2006, Issue 190
ARM-Based
Modern Answering Machine
Philips
ARM Design Contest 2005 First Prize
FOUR-PIN
ETHERNET
I
was fortunate enough to obtain an early sample of the
ENC28J60 Ethernet chip. It’s an interesting device.
The ENC28J60 makes it extremely easy to add Ethernet
connectivity to a small processor as long as the processor
carries a SPI. I chose this interface because it requires
only four pins: SPI IN, SPI OUT, CLOCK, and CHIP SELECT.
The
ENC28J60 includes two configurable LED drivers. I used
the default configuration, which is a Carrier Detect
indication on one LED and a Traffic Indicator on the
other. I mounted the LEDs on the PCB for debugging purposes,
but they aren’t shown outside the box. The chip requires
only two additional components: a decoupling capacitor
for the internal regulator and a bias resistor.
I
was initially concerned about the process of developing
a new driver for a new part. But the task was facilitated
because the chip performed exactly as documented despite
all the vendor warnings that came with an early sample.
