Blunk Microsystems Announces TargetLAPB Release 2003.1


San Jose, CA (October 1, 2003) Blunk Microsystems announces general availability of release 2003.1 of TargetLAPB, its embedded LAPB protocol stack. TargetLAPB is suited both for applications requiring strict ISO/IEC 7776 compatibility and for applications requiring high performance flow control and reliability over point-to-point networks. A significant new feature in release 2003.1 is optional support for ISO/IEC 13239 selective reject (SREJ) frames.


SREJ frames are not compliant with ISO/IEC 7776, but provide faster recovery from lost frames, particularly when the window size or transfer time is large. It is a desirable option when strict ISO/IEC 7776 compatibility is not required. Also, set asynchronous balanced mode (SABM/SAMBE) frames can be optionally sent in place of frame reject (FRMR) frames, for faster recovery from errors that drop the link.


TargetLAPB has been extensively tested and demonstrated interoperable with other ISO 7776 LAPB protocol stacks. Its easy to use application program interface includes LapbConnect(), LapbSend(), and LapbRecv(). Reliability is provided by CRC checks, frame sequence numbering, and positive acknowledgments with resends after timeouts. Flow control is provided by LAPBís sliding window protocol and receiver-not-ready (RNR) frames.


LAPB parameters T1, T2, T4, N2, window size, sequence number modulus (standard or extended), and addressing (DTE or DCE) are independently set for each channel. The following LAPB events can be reported by an optional callback function supplied to lapbInit(): N2 unacknowledged SABM/SABME commands, N2 unacknowledged DISC commands, N2 RNR responses, frame reject, physical disconnect, link reset, link reconnect, all I-frames acknowledged, and I-frame arrival.


Other features: the HDLC driver interface supports asserting and sensing modem control lines and the concurrent use of multiple point-to-point connections. Statistics are maintained on the number of connections/reconnections, number of frames sent and received, etc. and may be read and/or printed to stdout. If enabled, a short summary of every frame transmitted or received is printed to stdout on an ongoing basis, while the protocol stack runs.


TargetLAPB is royalty-free and includes complete ANSI C source code, a userís manual, a sample application, and one year of technical support. TargetLAPB was developed using Blunk Microsystems' TargetOS, but can be easily ported to another RTOS or used without an RTOS.


About Blunk Microsystems


Blunk Microsystems provides a broad spectrum of system software designed for embedded development including an RTOS, stacks, web server, static and flash file systems, device drivers, and board support packages. Blunk's products are available for off-the-shelf reference boards or can be ported to the customer's platform. Products are implemented in tight, clean code to be fast, small, reliable, and portable. TargetLAPB is available now and is priced at $26,000 for creating products at a single site. See for additional information or call (408) 323-1758.