Specifications

Refer to the API documentation on crossConnect() in section 7 for more details.
Debugging
Application development with SNAP offers an unprecedented level of interactivity in embedded
programming. Using Portal you can quickly upload bits of code, test, adjust, and try again. Some tips
and techniques for debugging:
• Make use of the “print” statement to verify control flow and values (be sure to connect STDIO to a
UART or Intercept STDOUT with Portal)
• When using Portal’s Intercept feature, you’ll get source line-number information, and symbolic
error-codes.
• Invoke “unit-test” script functions by executing them directly from the Snappy Modules Tree in
Portal’s Node Info panel.
• Use the included SNAP Sniffer to observe the RPC calls between devices.
Sample Application – Wireless UART
The following scenario is very common: two devices communicating over a RS-232 serial link.
RS-232 serial data cable
The two devices might be two computers, or perhaps a computer and a slave peripheral. For the
remainder of this section, we will refer to these devices as “end points.”
In some cases, a direct physical connection between the two end points is either inconvenient (long
distance) or even impossible (mobile end points).
You can use two SNAP nodes to wirelessly emulate the original hardwired connection. One SNAP
node gets paired with each end point. Each SNAP node communicates with its local end point using its
built-in RS-232 port, and communicates wirelessly with the other end point.
RS-232 802.15.4 Wireless RS-232
To summarize the requirements of this application:
We want to go from RS-232, to wireless, back to RS-232
Page 30 of 202 SNAP Reference Manual Document Number 600-0007K