User guide

Some changes to Asterisk were required to account for the lack of FPU and MMU on the Blackfin, for
example porting of DTMF routines from floating point to fixed point. The standard Asterisk PCI card
FXS/FXO port device drivers were ported to the Blackfin. Due to the richness of the Blackfins
peripherals (e.g. TDM serial and SPI ports), the Blackfin device drivers are actually simpler compared
to their PCI equivalents.
The 4 analog ports can be flexibly configured using single port FXS/FXO modules. The IP04 auto-
detects the module type when it powers up and helpful LEDs indicate what flavour (FXS or FXO) each
port is.
Use of the IP04 is similar to any other Asterisk box. You can telnet in, modify config files, or even use
the new Asterisk GUI. Setting up the IP04 is easier than a x86 PC based Asterisk system: you don't
need to install Asterisk, or even Linux. The IP04 comes pre-loaded with Asterisk and uClinux. Plug it in
and in a few seconds you can make calls. With the IP04 you get dial tone out of the box!
13.4.1 Open Hardware Design
The IP04 is an open hardware project. The Blackfin portion of the design is based on the BlackfinOne
DSP motherboard
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, and the FXO/FXS interfaces derived from Silicon Labs reference designs. The use
of open hardware techniques helped bring the design together quickly and with minimum effort.
The specific benefit of open hardware is lower R&D costs. This has been the experience with the IP04
project - we have developed a leading edge IP-PBX design with a modest investment of effort, simply
by working together with other open hardware and software developers.
Image 14: IP04 design manufactured by ATCOM.
59. BlackfinOne Project, http://blackfin.uclinux.org/gf/project/bf1
Page 55 TRICALCAR | www.wilac.net/tricalcar – Version: February 2008