LDP-1450 latencies examined

I whipped up a quick program to test the LDP-1450 latency and I was surprised as it is nothing like what the programming manual said to expect!

WARNING: My program only will read in a byte every 1 ms so these values should not be considered "final". I will need to write a more accurate program and try again later. 


matt_sony: -> 0x67
matt_sony: <- 0x80 (4 ms latency)
matt_sony: <- 0x00 (6 ms latency)
matt_sony: <- 0x10 (7 ms latency)
matt_sony: <- 0x00 (8 ms latency)
matt_sony: <- 0x01 (9 ms latency)
matt_sony: -> 0x56
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x41
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x3F
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x51
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x43
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x30
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x30
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x30
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x30
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x31
matt_sony: <- 0x0A (4 ms latency)
matt_sony: -> 0x40
matt_sony: <- 0x0A (4 ms latency)
matt_sony: <- 0x01 (312 ms latency)
matt_sony: -> 0x3A
matt_sony: <- 0x0A (1 ms latency)
matt_sony: -> 0x4F
matt_sony: <- 0x0A (1 ms latency)
matt_sony: -> 0x3A
matt_sony: <- 0x0A (1 ms latency)
matt_sony: -> 0x60
matt_sony: <- 0x30 (1 ms latency)
matt_sony: <- 0x30 (2 ms latency)
matt_sony: <- 0x30 (3 ms latency)
matt_sony: <- 0x30 (4 ms latency)
matt_sony: <- 0x32 (5 ms latency)
matt_sony: -> 0x60
matt_sony: <- 0x30 (1 ms latency)
matt_sony: <- 0x30 (2 ms latency)
matt_sony: <- 0x30 (3 ms latency)
matt_sony: <- 0x30 (4 ms latency)
matt_sony: <- 0x34 (5 ms latency)
matt_sony: -> 0x60
matt_sony: <- 0x30 (1 ms latency)
matt_sony: <- 0x30 (2 ms latency)
matt_sony: <- 0x30 (3 ms latency)
matt_sony: <- 0x30 (4 ms latency)
matt_sony: <- 0x35 (5 ms latency)

Observations:

The play (3A) and pause (4F) commands respond instantly.

Most other commands including STATUS INQ (67), starting a search, and entering digits, seem to take about 4 ms round trip.

And perhaps the most puzzling, ADDRESS INQ (60) sometimes responds instantly and other time takes 4 ms to respond (not shown here).