Module atsamd_hal::sercom::pad

Expand description

Type-level tools to configure SERCOM pads

This module helps configure Pins as SERCOM pads. It provides type-level tools to convert Pins to the correct PinMode and to enforce type-level constraints at compile-time.

Overview

A SERCOM pad is defined by two types, its corresponding Sercom instance and its PadNum, from Pad0 to Pad3. However, a given SERCOM pad can usually be mapped to several possible PinIds.

There are two primary traits defined in this module:

The IsPad trait is implemented on Pin types that are properly configured as SERCOM pads, with PinMode AlternateC or AlternateD. It acts as both a type class for SERCOM pads and as a type-level function to recover the corresponding Sercom and PadNum types from the Pin.
The GetPad trait maps each PinId to its corresponding, pad-related types. The PadMode alias uses GetPad to recover the corresponding PinMode for a given SERCOM pad, while the Pad alias recovers the configured Pin type.

SAMx5x chips do not allow arbitrary combinations of PinId for a given SERCOM. Instead, all PinIds must belong to the same IOSET. This module defines a [type-level enum], IoSet, to enforce this restriction, and the InIoSet type class is responsible for labeling each IsPad type with its corresponding, valid IoSet(s).