1//! Serial Peripheral Interface
2
3use nb;
4
5/// Full duplex (master mode)
6///
7/// # Notes
8///
9/// - It's the task of the user of this interface to manage the slave select lines
10///
11/// - Due to how full duplex SPI works each `read` call must be preceded by a `send` call.
12///
13/// - Some SPIs can work with 8-bit *and* 16-bit words. You can overload this trait with different
14/// `Word` types to allow operation in both modes.
15pub trait FullDuplex<Word> {
16 /// An enumeration of SPI errors
17 type Error;
18
19 /// Reads the word stored in the shift register
20 ///
21 /// **NOTE** A word must be sent to the slave before attempting to call this
22 /// method.
23 fn read(&mut self) -> nb::Result<Word, Self::Error>;
24
25 /// Sends a word to the slave
26 fn send(&mut self, word: Word) -> nb::Result<(), Self::Error>;
27}
28
29/// Clock polarity
30#[derive(Clone, Copy, PartialEq, Eq)]
31pub enum Polarity {
32 /// Clock signal low when idle
33 IdleLow,
34 /// Clock signal high when idle
35 IdleHigh,
36}
37
38/// Clock phase
39#[derive(Clone, Copy, PartialEq, Eq)]
40pub enum Phase {
41 /// Data in "captured" on the first clock transition
42 CaptureOnFirstTransition,
43 /// Data in "captured" on the second clock transition
44 CaptureOnSecondTransition,
45}
46
47/// SPI mode
48#[derive(Clone, Copy, PartialEq, Eq)]
49pub struct Mode {
50 /// Clock polarity
51 pub polarity: Polarity,
52 /// Clock phase
53 pub phase: Phase,
54}
55
56/// Helper for CPOL = 0, CPHA = 0
57pub const MODE_0: Mode = Mode {
58 polarity: Polarity::IdleLow,
59 phase: Phase::CaptureOnFirstTransition,
60};
61
62/// Helper for CPOL = 0, CPHA = 1
63pub const MODE_1: Mode = Mode {
64 polarity: Polarity::IdleLow,
65 phase: Phase::CaptureOnSecondTransition,
66};
67
68/// Helper for CPOL = 1, CPHA = 0
69pub const MODE_2: Mode = Mode {
70 polarity: Polarity::IdleHigh,
71 phase: Phase::CaptureOnFirstTransition,
72};
73
74/// Helper for CPOL = 1, CPHA = 1
75pub const MODE_3: Mode = Mode {
76 polarity: Polarity::IdleHigh,
77 phase: Phase::CaptureOnSecondTransition,
78};
79