---
license: cc-by-4.0
language:
- en
library_name: transformers
pipeline_tag: text-generation
datasets:
- AwaleSagar/gpio-llm-rpi5-actions
- HuggingFaceTB/smollm-corpus
tags:
- raspberry-pi
- gpio
- embedded
- structured-output
- json
- llama
- tiny
model-index:
- name: gpio-llm-base-rpi5
  results:
  - task:
      type: text-generation
      name: English GPIO request to JSON action
    dataset:
      name: gpio-llm-rpi5-actions (eval, 26,297 rows)
      type: AwaleSagar/gpio-llm-rpi5-actions
      config: gpio_actions_v2
      split: eval
    metrics:
    - name: Exact match, PyTorch fp32 greedy
      type: exact_match
      value: 95.17
    - name: Valid JSON, unconstrained
      type: accuracy
      value: 99.98
  - task:
      type: text-generation
      name: English GPIO request to JSON action
    dataset:
      name: gpio-llm-rpi5-actions (eval_core, 5,083 rows)
      type: AwaleSagar/gpio-llm-rpi5-actions
      config: gpio_actions_v2
      split: eval_core
    metrics:
    - name: Exact match, PyTorch fp32 greedy
      type: exact_match
      value: 93.47
    - name: Exact match, int8 C engine with grammar
      type: exact_match
      value: 93.51
    - name: Valid JSON, int8 C engine with grammar
      type: accuracy
      value: 100.00
---

# gpio-llm-base-rpi5

A 18.77M-parameter Llama-style model, trained from scratch, that turns one English request for a
Raspberry Pi 5 GPIO header into one JSON action:

```
User: turn on the LED on GPIO 17
Assistant: {"action":"gpio_write","pin":17,"value":"HIGH"}
```

This is the largest and most accurate of the three sizes. It is part of [GPIO-LLM](https://github.com/AwaleSagar/gpio-llm): the code, the C inference engine and the training scripts are on
GitHub, and the data is [AwaleSagar/gpio-llm-rpi5-actions](https://huggingface.co/datasets/AwaleSagar/gpio-llm-rpi5-actions). The other sizes are
[gpio-llm-pico-rpi5](https://huggingface.co/AwaleSagar/gpio-llm-pico-rpi5), [gpio-llm-nano-rpi5](https://huggingface.co/AwaleSagar/gpio-llm-nano-rpi5).

> ⚠️ The model is not a safety layer. It picks an action; a deterministic validator must check every action
> against the board's rules before anything touches a pin. Before the validator, 0.96% of the
> refusal or clarification cases in `eval` still come out as an executable action.

## Use it

**On a Raspberry Pi, with the C engine** (no Python, no ML framework; int8 weights):

```bash
git clone https://github.com/AwaleSagar/gpio-llm && make -C gpio-llm/engine
cd gpio-llm/engine
for f in base.gllm gpio_llm_bpe_12k.gltk grammar_v2.txt; do
  curl -LO https://huggingface.co/AwaleSagar/gpio-llm-base-rpi5/resolve/main/$f
done
build/gpiollm -m base.gllm -t gpio_llm_bpe_12k.gltk -g grammar_v2.txt "turn on the LED on GPIO 17"
build/gpiollm -m base.gllm -t gpio_llm_bpe_12k.gltk -g grammar_v2.txt \
    --context '{"device_mappings":{"fan":23}}' "switch the fan off"
```

The engine decodes under a grammar built from the training labels, so its output is always one of the JSON
shapes the dataset uses.

**With transformers** (fp32, unconstrained greedy decoding):

```python
from transformers import AutoModelForCausalLM, AutoTokenizer

repo = "AwaleSagar/gpio-llm-base-rpi5"
tok = AutoTokenizer.from_pretrained(repo)
model = AutoModelForCausalLM.from_pretrained(repo)
prompt = "User: turn on the LED on GPIO 17\nAssistant:"
ids = tok(prompt, return_tensors="pt").input_ids
out = model.generate(ids, max_new_tokens=200, do_sample=False)
print(tok.decode(out[0, ids.shape[1]:], skip_special_tokens=True).strip())
```

**Prompt format.** `User: <request>\nAssistant:`, optionally preceded by one context line such as
`Context: {"device_mappings":{"red_led":16}}\n` or `Context: {"available_pins":[16,17,18,25]}\n`. The answer
starts with a space and ends with `<|endoftext|>`. Multi-turn clarification follows the dataset format
(`...\nAssistant: <question>\nUser: <answer>\nAssistant:`).

## Model

| | |
|---|---|
| Architecture | `LlamaForCausalLM`: 8 layers, d_model 384, 12 heads (head_dim 32), SwiGLU FFN 1024, RoPE θ = 10000, RMSNorm ε = 1e-05, tied embeddings |
| Parameters | 18,770,304 |
| Vocabulary / context | 12,000 (byte-level BPE `gpio_llm_bpe_12k`, from the dataset repo) / 256 tokens |
| Weights | `model.safetensors` (fp32); `base.gllm`: int8 Q8_0, groups of 32, for the C engine |

## Training

Both stages ran on one rented RTX 4090 (24 GB), PyTorch 2.11 + CUDA 12.8, transformers 5.17.

| Stage | Data | Steps × batch | LR | Result | Time |
|---|---|---|---|---|---|
| Pretraining | 550M tokens of fineweb-edu-dedup (SmolLM corpus), 1 epoch | 8,392 × 65,536 tokens | 0.002, cosine, bf16 | val loss 3.2956 (perplexity 27.0) on 0.5M held-out tokens | 19.3 min |
| SFT | all 1,678,821 v2 train rows, 2 epochs; loss on the answer tokens only; 4×256 English tokens replayed every 12 steps (~1.1% of loss tokens) | 13,116 × 256 rows | 0.001, cosine | eval_core answer-token loss 0.0201 | 13.5 min |

The pretraining learning rate came from a sweep on the base shape at 55M tokens (lr → val loss): 0.0005 → 4.5519, 0.001 → 4.2294, 0.002 → 4.0577.
Logs are in `training/`.

## Evaluation

Exact match compares canonical JSON (same object, key order ignored) with the label. `eval` has 26,297 rows from
132 phrasing templates that never appear in training; `eval_core` is a 5,083-row stratified subset.

| Setup | Split | Exact match | Valid JSON | Unsafe execute* |
|---|---|---|---|---|
| PyTorch fp32, greedy | eval | 95.17% | 99.98% | 0.96% |
| PyTorch fp32, greedy | eval_core | 93.47% | 99.96% | 1.73% |
| C engine int8, no grammar | eval_core | 93.51% | 99.96% | 1.73% |
| C engine int8, grammar | eval_core | 93.51% | 100.00% | 1.84% |

\* Share of the refusal/clarification rows (1,845 in eval_core) where the model produced an
executable action instead. This is measured before any validator.

Latency with the C engine and the grammar, on all 5,083 eval_core requests from raw text (tokenizer included), 4 threads:

| Device | p50 | p95 |
|---|---|---|
| Raspberry Pi Zero 2 W, 64-bit Raspberry Pi OS, no heatsink (throttled at ~81 °C) | 498 ms | 1006 ms |
| Apple M5 laptop | 11.7 ms | 21.2 ms |

The Pi's outputs were byte-identical to the Mac's on all 5,083 rows. The int8 engine's greedy answers matched
fp32 PyTorch on 200/200 sampled rows (minimum next-token logit cosine 0.99759).

## Limitations

- **Pi 5 labels only.** The v2 data has no board field, so the labels follow the Pi 5 (RP1) rules, e.g.
  per-pin drive strength. On older boards, board-specific cases must be caught by the validator.
- **Synthetic English requests.** They come from templates, a rule-based generator and (v1) model rewrites.
  Real users will phrase things in ways the model has not seen.
- **Scope.** Digital I/O, PWM, pulses, waits, sequences, errors and clarifications only. There are no bus
  transactions (I2C/SPI/UART data), and the context is 256 tokens.

## Files

| File | What it is |
|---|---|
| `model.safetensors`, `config.json`, `generation_config.json` | fp32 transformers checkpoint |
| `tokenizer.json`, `tokenizer_config.json` | the dataset's `gpio_llm_bpe_12k` tokenizer |
| `base.gllm` | int8 weights for the C engine |
| `gpio_llm_bpe_12k.gltk`, `grammar_v2.txt` | tokenizer and output grammar for the C engine |
| `training/` | training logs, LR sweep, eval summaries (JSON) |

## Licence and attribution

The weights are released under **CC-BY-4.0**; the code on GitHub is Apache-2.0. The training data carries
its own terms:
- the fine-tuning data, [AwaleSagar/gpio-llm-rpi5-actions](https://huggingface.co/datasets/AwaleSagar/gpio-llm-rpi5-actions), is CC-BY-4.0
- its knowledge-base scenes are CC BY-SA 4.0
- the user wording in its v1 `teacher_*` rows was generated with third-party models, so check those
  providers' terms on using model outputs
- the pretraining text is [fineweb-edu-dedup](https://huggingface.co/datasets/HuggingFaceTB/smollm-corpus) (ODC-By 1.0)