Built-in Communications Tools

Serial Tool

An endpoint can include

kPacket

,

kEOP

, and

kMore

flags to control the sending

and receiving of framed (packetized) data with the framed asynchronous serial
tool. For more information on these flags, see "Sending Data" (page 23-11).

The following is an example that shows how to create an endpoint that uses the
framed asynchronous serial tool:

myFramedEP := {_proto:protoBasicEndpoint};
myOptions := [

{ label: kCMSFramedAsyncSerial,
type: 'service,
opCode: opSetRequired } ];

returnedOptions:= myFramedEP:Instantiate(myFramedEP,
myOptions);

The framed asynchronous serial tool uses the standard asynchronous serial tool
options, as well as two framing options, which are summarized in Table 24-3.
These options are described in detail in "Options for the Framed Asynchronous
Serial Tool" (page 21-29) in Newton Programmer's Reference.

The default settings for the

kCMOFramingParms

option implement BSC framing,

as shown in Figure 24-1.

Default serial framing

Each packet is framed at the beginning by the 3-character SYN-DLE-STX header.
The packet data follows; if a DLE (escape character) occurs in the data stream,

Summary of framed serial options

kCMOFramingParms

"fram"

Any time

Configures data framing parameters.

kCMOFramedAsyncStats

"frst"

Any time

Read-only option returns the number
of bytes discarded while looking for
a valid header.

Octet 1

SYN
Flag
0001011

DLE
Flag
0001000

STX
Flag
0000001

Message . . .

DLE
Flag
0001000

ETX
Flag
0000001

Frame
Check
Sequence

2

3

. . . . . . . . . . . . . . . . . .

N-3

N-2

N-1

N