# `ATECC508A.Transport`
[🔗](https://github.com/nerves-hub/atecc508a/blob/v1.5.0/lib/atecc508a/transport.ex#L7)

ATECC508A transport behaviour

# `t`

```elixir
@type t() :: {module(), any()}
```

# `detected?`

```elixir
@callback detected?(arg :: any()) :: boolean()
```

# `info`

```elixir
@callback info(id :: any()) :: map()
```

# `init`

```elixir
@callback init(args :: any()) :: {:ok, t()} | {:error, atom()}
```

# `request`

```elixir
@callback request(
  id :: any(),
  payload :: binary(),
  timeout :: non_neg_integer(),
  response_payload_len :: non_neg_integer()
) :: {:ok, binary()} | {:error, atom()}
```

# `transaction`

```elixir
@callback transaction(
  id :: any(),
  callback :: (request :: fun() -> {:ok, any()} | {:error, atom()})
) :: {:ok, any()} | {:error, atom()}
```

# `detected?`

```elixir
@spec detected?(t()) :: boolean()
```

Check whether the ATECC508A is present

The transport implementation should do the minimum work to figure out whether
an ATECC508A is actually present. This is called by users who are unsure
whether the device has an ATECC508A and want to check before sending requests
to it.

# `info`

```elixir
@spec info(t()) :: map()
```

Return information about this transport

This information is specific to this transport. No fields are required.

# `request`

```elixir
@spec request(t(), binary(), non_neg_integer(), non_neg_integer()) ::
  {:ok, binary()} | {:error, atom()}
```

Send a request to the ATECC508A and wait for a response

This is the raw request. The transport implementation takes care of adding
and removing CRCs.

# `transaction`

```elixir
@spec transaction(t(), (fun() -> {:ok, any()} | {:error, atom()})) ::
  {:ok, any()} | {:error, atom()}
```

Run a callback function inside a transaction that doesn't sleep

Use a transaction when multiple requests need to be sent without putting the
chip to sleep. For example, when a value needs to be stored in SRAM and then
acted on, since sleeping will clear the SRAM.

`callback` is a function that provides one argument, `request`, and expects a
return value of `{:ok, data}` or `{:error, reason}`. `request` is an anonymous
function whose args follow the public function `ATECC508A.Transport.request/4`,
except without the first arg (`t()`) since this is provided to `transaction`.

The success/error tuple returned by the callback function is returned
by `transaction`.

## Example

```ex
{:ok, transport} = ATECC508A.Transport.I2C.init()

{:ok, signature} =
  ATECC508A.Transport.transaction(transport, fn request ->
    # NONCE command (0x16)
    {:ok, <<0>>} = request.(<<0x16, 0x43, 0, 0, signature_digest::binary>>, 29, 1)
    # SIGN command (0x41)
    request.(<<0x41, 0xA0, 0, 0>>, 115, 64)
  end)
```

---

*Consult [api-reference.md](api-reference.md) for complete listing*