771 snn_lif_neurons :: Quicker, easier and cheaper to make your own chip!

771 : snn_lif_neurons

Author: david

Description: SNN heart-monitor classifier using banded LIF neurons

Clock: 50000000 Hz

Tiny Tapeout SNN Heart Monitor

Architecture: ARCHITECTURE.md · Component datasheet: DATASHEET.md · User manual (demoboard / HIL): USER_MANUAL.md · Companion ADC manual: ADC USER_MANUAL (heart_monitor_adc_art_ttsky26c — fabrication companion)

How it works

This design is a compact spiking neural network (SNN) heart-beat classifier for Tiny Tapeout.

A 12-bit ADC sample is presented on ui_in[7:0] + uio_in[3:0].
Pulsing uio_in[4] (sample_en) feeds the sample into:
- Heartbeat_Segmenter — detects an R-peak (>= 2200) and opens a fixed evaluation window.
- Delta_Encoder — emits gentle vs steep up/down spikes plus direction-flip events.
A 5-neuron Parallel_SNN_Matrix (one neuron per AAMI-style class) integrates those spikes with class-specific weights and leaks.
MultiClass_SNN_Voter picks the winning class when the window ends.
An alarm counter asserts alarm only after 3 consecutive anomaly classifications (classes 1, 2, or 4). Classes 0 (Normal) and 3 (Fusion) clear the streak.

Class	Meaning	Typical stimulus
0	Normal	Gentle rising slope
1	Supra-ventricular	Gentle falling slope
2	Ventricular	Steep rising slope
3	Fusion	Steep falling slope
4	Unknown / noise	Zigzag / alternating edges

How to test

From the test/ directory:

pip install -r requirements.txt
make -B

The cocotb suite checks:

gentle rise → class 0
steep rise → class 2
zigzag → class 4
alarm quiet for 2 ventricular beats, fires on the 3rd, clears on Normal
MIT-BIH stream — plays test/data/mitbih_100_excerpt.csv into the ADC pins, requires several diag_valid detections, and logs a class histogram plus optional annotation agreement (informational; not a hard accuracy gate)

See test/data/README.md for PhysioNet citation and scaling.

On hardware / FPGA:

Hold baseline ADC ~150.
Drive an R-peak (>= 2200), then a morphology slope for ~100 sample_en pulses.
Read uo_out[2:0] when uo_out[3] (diag_valid) pulses.
Observe uo_out[4] (alarm) after three consecutive anomaly beats.

External hardware

Optional: external ADC or microcontroller streaming 12-bit samples into the pin-mapped ADC bus, with a sample strobe on uio[4]. Setup and test: USER_MANUAL.md §4.
Optional: companion Tiny Tapeout SAR ADC heart_monitor_adc_art_ttsky26c (12-bit ~500 SPS + decorative met4 art; electrically same as the pristine ADC); wire per its docs/INTEGRATION.md.
Optional: LED on uo[4] for the anomaly alarm.

#	Input	Output	Bidirectional
0	adc[0]	class[0]	adc[8]
1	adc[1]	class[1]	adc[9]
2	adc[2]	class[2]	adc[10]
3	adc[3]	diag_valid	adc[11]
4	adc[4]	alarm	sample_en
5	adc[5]
6	adc[6]
7	adc[7]

Input

Output

Bidirectional

adc[0]

class[0]

adc[8]

adc[1]

class[1]

adc[9]

adc[2]

class[2]

adc[10]

adc[3]

diag_valid

adc[11]

adc[4]

alarm

sample_en

adc[5]

adc[6]

adc[7]

Chip location