1//! A delay driver based on SysTick.
2
3use crate::peripheral::{syst::SystClkSource, SYST};
4use embedded_hal::blocking::delay::{DelayMs, DelayUs};
5
6/// System timer (SysTick) as a delay provider.
7pub struct Delay {
8 syst: SYST,
9 frequency: u32,
10}
11
12impl Delay {
13 /// Configures the system timer (SysTick) as a delay provider.
14 ///
15 /// `ahb_frequency` is a frequency of the AHB bus in Hz.
16 #[inline]
17 pub fn new(syst: SYST, ahb_frequency: u32) -> Self {
18 Self::with_source(syst, ahb_frequency, SystClkSource::Core)
19 }
20
21 /// Configures the system timer (SysTick) as a delay provider
22 /// with a clock source.
23 ///
24 /// `frequency` is the frequency of your `clock_source` in Hz.
25 #[inline]
26 pub fn with_source(mut syst: SYST, frequency: u32, clock_source: SystClkSource) -> Self {
27 syst.set_clock_source(clock_source);
28
29 Delay { syst, frequency }
30 }
31
32 /// Releases the system timer (SysTick) resource.
33 #[inline]
34 pub fn free(self) -> SYST {
35 self.syst
36 }
37
38 /// Delay using the Cortex-M systick for a certain duration, in µs.
39 #[allow(clippy::missing_inline_in_public_items)]
40 pub fn delay_us(&mut self, us: u32) {
41 let ticks = (u64::from(us)) * (u64::from(self.frequency)) / 1_000_000;
42
43 let full_cycles = ticks >> 24;
44 if full_cycles > 0 {
45 self.syst.set_reload(0xffffff);
46 self.syst.clear_current();
47 self.syst.enable_counter();
48
49 for _ in 0..full_cycles {
50 while !self.syst.has_wrapped() {}
51 }
52 }
53
54 let ticks = (ticks & 0xffffff) as u32;
55 if ticks > 1 {
56 self.syst.set_reload(ticks - 1);
57 self.syst.clear_current();
58 self.syst.enable_counter();
59
60 while !self.syst.has_wrapped() {}
61 }
62
63 self.syst.disable_counter();
64 }
65
66 /// Delay using the Cortex-M systick for a certain duration, in ms.
67 #[inline]
68 pub fn delay_ms(&mut self, mut ms: u32) {
69 // 4294967 is the highest u32 value which you can multiply by 1000 without overflow
70 while ms > 4294967 {
71 self.delay_us(4294967000u32);
72 ms -= 4294967;
73 }
74 self.delay_us(ms * 1_000);
75 }
76}
77
78impl DelayMs<u32> for Delay {
79 #[inline]
80 fn delay_ms(&mut self, ms: u32) {
81 Delay::delay_ms(self, ms);
82 }
83}
84
85// This is a workaround to allow `delay_ms(42)` construction without specifying a type.
86impl DelayMs<i32> for Delay {
87 #[inline(always)]
88 fn delay_ms(&mut self, ms: i32) {
89 assert!(ms >= 0);
90 Delay::delay_ms(self, ms as u32);
91 }
92}
93
94impl DelayMs<u16> for Delay {
95 #[inline(always)]
96 fn delay_ms(&mut self, ms: u16) {
97 Delay::delay_ms(self, ms:u32::from(ms));
98 }
99}
100
101impl DelayMs<u8> for Delay {
102 #[inline(always)]
103 fn delay_ms(&mut self, ms: u8) {
104 Delay::delay_ms(self, ms:u32::from(ms));
105 }
106}
107
108impl DelayUs<u32> for Delay {
109 #[inline]
110 fn delay_us(&mut self, us: u32) {
111 Delay::delay_us(self, us);
112 }
113}
114
115// This is a workaround to allow `delay_us(42)` construction without specifying a type.
116impl DelayUs<i32> for Delay {
117 #[inline(always)]
118 fn delay_us(&mut self, us: i32) {
119 assert!(us >= 0);
120 Delay::delay_us(self, us as u32);
121 }
122}
123
124impl DelayUs<u16> for Delay {
125 #[inline(always)]
126 fn delay_us(&mut self, us: u16) {
127 Delay::delay_us(self, us:u32::from(us))
128 }
129}
130
131impl DelayUs<u8> for Delay {
132 #[inline(always)]
133 fn delay_us(&mut self, us: u8) {
134 Delay::delay_us(self, us:u32::from(us))
135 }
136}
137