Retinal Prosthesis Dissertation - Student Home Pages

time for T partial_spike ; nominally the `quarter component of a biphasic pulse, is
156.25ns/4 = 39.0625ns (a thousandth of T packet ) giving a frequency of 25.6MHz.
f packet T spike
f spike (f biphasic )
fps T frame row col pix_count T packet (ns) (kHz) (T biphasic )(ns) (MHz)
25 0.04 32 32 1024 39062.5 25600 156.25 6.4
25 0.04 16 16 256 156250 6400 625 1.6
25 0.04 8 8 64 625000 1600 2500 0.4
25 0.04 4 4 16 2500000 400 10000 0.1
25 0.04 2 2 4 10000000 100 40000 0.025
50 0.02 32 32 1024 19531.25 51200 78.125 12.8
50 0.02 16 16 256 78125 12800 312.5 3.2
50 0.02 8 8 64 312500 3200 1250 0.8
50 0.02 4 4 16 1250000 800 5000 0.2
50 0.02 2 2 4 5000000 200 20000 0.05
100 0.01 32 32 1024 9765.625 102400 39.0625 25.6
100 0.01 16 16 256 39062.5 25600 156.25 6.4
100 0.01 8 8 64 156250 6400 625 1.6
100 0.01 4 4 16 625000 1600 2500 0.4
100 0.01 2 2 4 2500000 400 10000 0.1
Table 11 clocking calculations
The following table (taken from “fps_calcs.xls”) illustrates these calculations:
Circa 25MHz f f(kHz) f(MHz) T periodic T periodic(ns) T periodic(µ)
T aer_stream 25 0.025 0.000025 0.04 40000000 40000
3.90625E-
T pixel 25600 25.6 0.0256 05 39062.5 39.0625
T spike 6400000 6400 6.4 1.5625E-07 156.25 0.15625
3.90625E-
T partial_spike circa 40ns 25600000 25600 25.6 08 39.0625 0.0390625
The following sub-table either reads each frame four times or allows for 100fps;
Circa 100MHz f f(kHz) f(MHz) T periodic T periodic(ns) T periodic(µ)
T aer_stream 100 0.1 0.0001 0.01 10000000 10000
T pixel 102400 102.4 0.1024
9.76563E-
06 9765.625 9.765625
T spike 25600000 25600 25.6
3.90625E-
08 39.0625 0.0390625
T partial_spike circa 10ns 102400000 102400 102.4
9.76563E-
09 9.765625 0.009765625
Using a 100MHz clock and showing the effect on T partial_spike !
Exactly 100MHz f f(kHz) f(MHz) T periodic T periodic(ns) T periodic(µ)
T aer_stream 97.65625 0.0976563 9.77E-05 0.01024 10240000 10240
T pixel 100000 100 0.1 0.00001 10000 10
T spike 25000000 25000 25 0.00000004 40 0.04
T partial_spike exactly
10ns 100000000 100000 100 0.00000001 10 0.01
Table 12 simulation clocking
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