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SCHEMATIC 1. This is a classic implementation of the MRF24WB0MA. Note the absence of any type of crystal.
The Simple Mail Transfer Protocol is designed to be a
relatively simple means of transporting mail via the Internet.
In the good old days, one could manually send an email
using an ASCII terminal and a Telnet session. With the
advent of SPAM and all of its wonders and mutations,
authenticated email has become the domain of specialized
email programs that run on PCs.
While companies like MarshallSoft provide tricky
software libraries for C and BASIC, our folks at Microchip
are covering email’s embedded side. The latest version of
the Microchip TCP/IP stack contains code that enables most
PIC18, PIC24, and PIC32 class microcontrollers to send open
and authenticated email messages.
Microchip goes beyond covering the embedded email
model with its microcontrollers. A series of their wired and
wireless Ethernet adapters complete the tool set necessary
to send an email through the routers and servers that make
up the Internet. For stationary robots, the 10Base-T wired
email solutions include the ENC28J60 and PIC18F97J60.
Roaming robots can keep in touch via the MRF24WB0MA
Wireless SMTP Hardware
The MRF24WB0MA is easy to implement. However,
why would we want to scratch-build our email hardware
when a perfectly good ready-to-go platform already exists?
The Wi-Fi Comm demo board shown in Photo 1 is more
than capable of assembling and sending an SMTP message.
The Wi-Fi board is based on a PIC32MX695F512H. The
only other active components on it are a boost regulator
and the MRF24WB0MA. The MCP1642 is a higher current
version of the MCP1640 boost regulator that is capable of
starting up and working from a single-cell alkaline battery.
Microchip plans to release the MCP1642 toward the end of
the year. Three LEDs and a pushbutton switch emulate a
display and keyboard, respectively. Just enough I/O is
exposed on the sensor expansion port to interface an SPI or
I2C peripheral and a pair of USARTs. You can get
connection details from Schematic 1.
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