neuron-vhdl

Implementation of a neuron and 2 neuronal networks in vhdl for a ZedBoard.

The XOR neuronal network has been built to test the neurons and it's quite simple. The Xilinx project can be download from the next link. https://mega.nz/#!AdQDAAjJ!5pygQHFxFP4DshoSe3a9r0awPDhHk_6rOQcBCpiAAUE

Another network has been built to recognize characters, its weights has been obtained from PyBrain. https://mega.nz/#!BZgglLpI!3OnpBpzFnOsBLb6zIpRHiVG9nZFIWedznzwWJSLVxB4

Presentation

There is a presentation in spanish explaining the work done.

Sigmoid aproximation

Sigmoid function has been implementated with an aproximation based on a ROM. All the code and the whole aproximation is located into the "src/sigmoid.vhd" file. The aproximation mean error 0,00013.

Sigmoid function, aproximation and error

Aproximation considering codification error and resource limit error.

The error commited due to resource limit means that ROMs size cannot be as big as we want so only a restricted number of entries can be used, the aproximation considering only this error has been painted in blue. Moreover the codification error is related to the fact that we only have 32bits (Q15.16) to codify numbers, this aproximation considering both kind of errors has been painted in violet.

Error around the zero

IP package

The IP package includes a neuron with 6 inputs. It uses AXI LITE protocol to communicate, and it has been developed for a Zynq ZedBoard.