Just a note to maybe save someone else the head scratching I went through last night.  In some of the SRV-1 docs and marked on the breakout board, the TMR6 and TMR7 labeling is swapped.
 
It should be:
Pin 5  TX1/TMR7
Pin 6  RX1/TMR6
 
I was trying to get pulse width capture working for a MaxBotix EZ1 on TMR6 using the breakout board, but it didn't go well until I discovered this mistake on the PCB labeling.  I'm much more familiar with the HRM section on timers now though.    
 
Mislabeled:
http://www.surveyor.com/blackfin/bfin-srv1-signals.txt
http://www.surveyor.com/blackfin/bfin-breakout-v1.png
 
Correct:
http://www.surveyor.com/blackfin/SRV1-bfin-schematic.pdf
http://www.surveyor.com/blackfin/BF537-datasheet.pdf (page 20)
 
Michael