# Vanilla TFLM baseline

## Goal

Produce the baseline that gives the heliaRT and heliaAOT numbers their
meaning. You will learn what the `tflm` engine is and is not, how to pick
its kernel backend, and how its binary compares.

## Hardware and wiring

An Apollo510 EVB on its J-Link USB port; no other connections.

## Software prerequisites

hpx, the GNU Arm toolchain, CMake, Ninja and J-Link software
([Install](https://ambiqai.github.io/helia-profiler/getting-started/install/)). No extra: the `tflm` engine
resolves the `nsx-tflite-micro` module from the registry.

## Config file

[`examples/quickstart/hpx_tflm_baseline.yml`](https://github.com/AmbiqAI/helia-profiler/blob/main/examples/quickstart/hpx_tflm_baseline.yml):

```yaml
model:
  path: examples/quickstart/kws_model.tflite
  arena_size: 131072
engine:
  type: tflm
  backend: cmsis_nn    # reference or cmsis_nn
target:
  board: apollo510_evb
  toolchain: arm-none-eabi-gcc
profiling:
  pmu_counters:
    cpu: default
    memory: default
  per_layer: true
  iterations: 3
  warmup: 1
power:
  enabled: false
output:
  format: csv
  dir: ./results/results_tflm_baseline
```

`engine.backend: cmsis_nn` links upstream Arm CMSIS-NN; `reference`
selects TFLM's portable C kernels. Neither enables Ambiq's HELIA kernels;
that is the point of the baseline.

## Run

From the repository root (the model path is repository-relative):

```bash
hpx profile --config examples/quickstart/hpx_tflm_baseline.yml
```

## Expected output

From the nightly case named under Validated on (the arena progress bar is omitted):

```
  Engine              tflm
  Board               apollo510_evb
  Layers              13
  Total cycles        2,118,339
  Clean E2E cycles    2,109,120  (-0.4% vs per-layer sum)
  Arena      27,300 / 32,768 bytes  83%
  Model      53,744 bytes
  Binary Sections
  Section          Size
  text          507,932
  data          154,796
  bss            89,284
  reserved      362,380
  total       1,114,392
  Validity: VALID
```

## How to read it

- 2,109,120 clean cycles against heliaRT's 2,051,232 and heliaAOT's
  2,044,512 on the same board, model and toolchain: for this model the
  arithmetic runs in CMSIS-NN either way, so the engines separate by a few
  percent. Models with operators that heliaRT fuses show a larger gap;
  the baseline is what tells you how large.
- `.text` is 507,932 bytes, 1.8 times heliaRT's 278,596, because the
  upstream interpreter links its full operator set and resolver.
- The per-layer table has the same columns as every other engine, so a
  row-by-row comparison with `hpx compare` works
  ([Compare engines](https://ambiqai.github.io/helia-profiler/examples/engine-comparison/)).
- The result describes the vanilla port; it is not an Ambiq-optimised
  number and should not be quoted as one.

## Variations

- Reference kernels: copy the config, set `backend: reference`, keep
  everything else, and compare the two TFLM runs to see what CMSIS-NN buys
  on this core.
- Another model: change `model.path` and `model.arena_size`; the arena
  usage line tells you how much you needed.
- Cortex-M4 boards (`apollo3p_evb`, `apollo4l_blue_evb`) run the same
  engine with cycle counts only.

## Validated on

| | |
|---|---|
| Board | `apollo510_evb`, `lp` clock tier |
| Run | nightly hardware validation [run 35078330526](https://github.com/AmbiqAI/helia-profiler/actions/runs/35078330526), 2026-09-16, hpx 0.1.6 at `0714893` |
| Case | `apollo510_evb-kws-tflm-arm-arm-none-eabi-gcc-rtt-auto` (`arm` is the CMSIS-NN provider), verdict `valid` |
| nsx modules | `nsx-tflite-micro` 7afcf2b, `arm-cmsis-nn` 6d21a6f, `nsx-ambiq-sdk` a9f4ec2, `nsx-pmu-armv8m` 5725c06 (bundle `nsx.lock`) |
| Toolchain | arm-none-eabi-gcc 15.2.1, CMake 4.1.2 |
| Differences from the config above | `arena_size: 32768`, `pmu_counters: {cpu: default}` in the nightly case |
| `reference` backend | not yet validated: the nightly suite runs the CMSIS-NN backend only |
| Bundle | [`examples/results/hardware-validation-2026-09-16/apollo510_evb-kws-tflm-arm-arm-none-eabi-gcc-rtt-auto/`](https://github.com/AmbiqAI/helia-profiler/tree/main/examples/results/hardware-validation-2026-09-16/apollo510_evb-kws-tflm-arm-arm-none-eabi-gcc-rtt-auto) |