- Author: Jason Eshraghian
- Description: Implement a Hodgkin-Huxley neuron in silicon.
- GitHub repository
- GDS submitted
- HDL project
- Extra docs
- Clock: 20000000 Hz
- External hardware:

Apply an input current injection to the LIF neuron. This will modify a neuron membrane potential, and with sufficient current injection, will cause periodic action potentials.

After reset, all state variables will be initialized. A minimum of 2 clock cycles of reset is needed.

An 8-bit input current is then applied to uio_in. The current is treated as the LSB of a 16-bit signal by concatenating 8x0’s to the front. The first bit is a sign bit, the following 8-bits are treated as the whole number while the final 7-bits are the fraction. The current is interpreted in dimensions of uA/cm^2. This means the maximum value that can be represented is 1.992 uA/cm^2.

The membrane potential of the neuron will respond accordingly. Larger currents will elicit more firing. Simulations show that the neuron will start firing, reach a steady state where it stops firing in absence of input stimulus, and start firing again if the current exceeds approximately 8’b00001100 = 8’d12.

# | Input | Output | Bidirectional |
---|---|---|---|

0 | current bit 11 | membrane potential bit a | membrane potential output bit i |

1 | current bit 12 | membrane potential bit b | membrane potential fractional output bit j |

2 | current bit 13 | membrane potential bit c | membrane potential fractional output bit k |

3 | current bit 14 | membrane potential bit d | membrane potential fractional output bit l |

4 | current bit 15 | membrane potential bit e | membrane potential fractional output bit m |

5 | current bit 16 | membrane potential bit f | membrane potential fractional output bit n |

6 | current bit 17 | membrane potential bit g | membrane potential fractional output bit o |

7 | current bit 18 | membrane potential bit h | membrane potential fractional output bit p |