User manual

Local Terminal

A command like crossConnect(DS_UART0, DS_STDIO) will send characters received on UART0 to your

SNAPpy script for processing. The characters will be reported to your script via your speciﬁed HOOK_STDIN

handler. Any text “printed” (using the print statement) will be sent out that same serial port.

This makes it possible to implement applicaons like a Command Line Interface.

Remote Terminal

A command like crossConnect(DS_TRANSPARENT, DS_STDIO) will send characters received wirelessly to

your SNAPpy script for processing. Characters “printed” by your SNAPpy script will be sent back out over the air.

This is oen used in conjuncon with a

crossConnect(DS_UARTx, DS_TRANSPARENT) in some other SNAP

Node.

Packet Serial

The last column of the table shows the eﬀect of various combinaons using DS_PACKET_SERIAL.

A command like

crossConnect(DS_UART0, DS_PACKET_SERIAL) will conﬁgure the unit to talk Synapse’s

Packet Serial protocol over UART0. This enables RS-232 connecon to a PC running Portal or SNAP Connect.

It also allows serial connecon to another SNAP Node, if the appropriate “cross-over” cable is used.

This allows “bridging” of separate SNAP Networks (networks that are on diﬀerent channels and/or diﬀerent

Network IDs, or two nodes that work in diﬀerent radio frequency ranges).

A command like

crossConnect(DS_UART1, DS_PACKET_SERIAL) will conﬁgure the unit to talk Synapse’s

Packet Serial protocol over UART1. On some SNAP demonstraon boards, one UART will be a true RS-232 serial

connecon, and the other will be a USB serial connecon.

Refer to the API documentaon on crossConnect() in the SNAP Reference Manual for more details.

Debugging

Applicaon development with SNAP oﬀers an unprecedented level of interacvity in embedded programming.

Using Portal you can quickly upload code, test, adjust, and try again. Some ps 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 informaon, and symbolic error-

codes.

• Invoke “unit-test” script funcons by execung 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.

SNAP® Network Operang System 23