PR1 Daughter Card

The PR1 card project has made rapid progress lately. The PR1 card hardware has been designed and prototype PCBs assembled. Just one day after the "solder cooled" the PR1 card Layer 1 (physical layer) was up with clear alarms on both ends of the link. Since then Layer 2 has been brought up and the first calls have been made. Thanks to Mark and Mathieu for doing a fantastic job on the hardware design and driver port to the Blackfin.

The driver has progressed to the point where Asterisk recognises the card and calls have be made:

bf1*CLI> zap show status
Description                              Alarms     IRQ        bpviol     CRC4
BF1-PR1 T1/E1 Card 1                     OK         0          0          0
bf1*CLI> pri show span 1
Primary D-channel: 24
Status: Provisioned, Down, Active
Switchtype: National ISDN
Type: CPE
Window Length: 0/7
Sentrej: 0
SolicitFbit: 0
Retrans: 0
Busy: 0
Overlap Dial: 0
T200 Timer: 1000
T203 Timer: 10000
T305 Timer: 30000
T308 Timer: 4000
T309 Timer: -1
T313 Timer: 4000
N200 Counter: 3
bf1*CLI> zap show channels
   Chan Extension  Context         Language   MOH Interpret
 pseudo            default                    default
      1            DID_trunk_5                default
      2            DID_trunk_5                default
      3            DID_trunk_5                default
      4            DID_trunk_5                default
      5            DID_trunk_5                default
      6            DID_trunk_5                default
      7            DID_trunk_5                default
      8            DID_trunk_5                default
      9            DID_trunk_5                default
     10            DID_trunk_5                default
     11            DID_trunk_5                default
     12            DID_trunk_5                default
     13            DID_trunk_5                default
     14            DID_trunk_5                default
     15            DID_trunk_5                default
     16            DID_trunk_5                default
     17            DID_trunk_5                default
     18            DID_trunk_5                default
     19            DID_trunk_5                default
     20            DID_trunk_5                default
     21            DID_trunk_5                default
     22            DID_trunk_5                default
     23            DID_trunk_5                default
bf1*CLI>

The PR1 configuration has been incorporated into the Asterisk GUI, and can be managed just like analog lines:

Current work is focused on development of a complete PR-Appliance that combines E1/T1 with a Blackfin chip on a single card. More details from this post on the Astfin Blog.

A team of several people from around the world are working on the project. As usual, the hardware design is completely open and is available for download from PR1 SVN.

Twelve prototype PCBs have been sent to people all over the globe e.g. North America, Indonesia, Australia, China and Europe. Would you like to be involved in a leading edge project to build an embedded Primary Rate IP-PBX? Please contact Mark or Mathieu Padovani.

The heart of the design is the Infineon 2256 (aka FALC56) "E1/T1/J1 Framer and Line Interface" chip. This chip was chosen as it is already used on hardware supported by Asterisk (Digium TDM110 card) and has an existing driver (zaptel wcte11xp.c). This driver has been ported to the Blackfin by replacing the PCI interface code with an interface customised for the Blackfin.

The PR1 card has two busses; a TDM bus to transfer voice data, and a parallel bus used for control and configuration data.

The parallel bus is memory mapped to the Blackfins ASYNC memory bus, which is easily accessible on the BlackfinOne via the headers. The BlackfinOne CPLD is used to decode the parallel bus for the PR1 card.

The choice of matching resistors is a compromise between E1 and T1 (thanks to Jan Berger for this suggestion).

Echo cancellation will be handled by hardware chip sets or possibly the Oslec open source line echo canceller.

For all PR1 project enquiries (business or technical) please contact Mark or Mathieu Padovani, rather than David Rowe.