ATECC508A.Transport behaviour (atecc508a v1.4.0)

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ATECC508A transport behaviour

Summary

Types

t()

Callbacks

detected?(arg)
info(id)
init(args)
request(id, payload, timeout, response_payload_len)
transaction(id, callback)

Functions

detected?(arg)

Check whether the ATECC508A is present

info(arg)

Return information about this transport

request(arg, payload, timeout, response_payload_len)

Send a request to the ATECC508A and wait for a response

transaction(arg, callback)

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

Types

t()

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

Callbacks

detected?(arg)

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

info(id)

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

init(args)

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

request(id, payload, timeout, response_payload_len)

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

transaction(id, callback)

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

Functions

detected?(arg)

@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(arg)

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

Return information about this transport

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

request(arg, payload, timeout, response_payload_len)

@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(arg, callback)

@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

{: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)