Retinal Prosthesis Dissertation - Student Home Pages

2.6.2 FPGA representation of epi_retinal approach
The following diagram (figure 21) gives a basic overview of the epi_retinal
prosthesis. The sender chip receives the camera output and converts it to an AER
protocol[170]. This serial communication of a stream of pulses is wired from the
sender chip to the receiver chip. In this diagram the separation of the receiver chip
into two distinct parts i.e. external to the body and internal to the body is not shown,
this is ably discussed in other papers [53]. The action of the receiver chip is to
convert the serial transmission into the parallel form required for transmission to the
retinal implant incorporating timing considerations, to form biphasic pulses. The
implant (Addressing the implant) is then addressed in the sense that all wires now
entering the eyeball carry a separate stream of information for each electrode to be
driven by the post processing electrode drivers attached to the electrode array.
AER protocol
Receiver.
Retinal implant.
PISO
Sender.
Digital address
stream (AER)
Serial to parallel conversion
Timing considerations
Addressing the implant
Form biphasic pulses
Electrode
array
Control/
addressing
Figure 21 FPGA view of processing
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