capsules_extra/
buzzer_pwm.rs

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1// Licensed under the Apache License, Version 2.0 or the MIT License.
2// SPDX-License-Identifier: Apache-2.0 OR MIT
3// Copyright Tock Contributors 2022.
4
5//! Service capsule for a buzzer that uses a PWM pin.
6//!
7//! ## Instantiation
8//!
9//! Instantiate the capsule for use as a service capsule, using a virtual pwm buzzer
10//! and a virtual alarm. For example:
11//!
12//! ```rust,ignore
13//! # use kernel::static_init;
14//!
15//! let mux_pwm = static_init!(
16//!     capsules::virtual_pwm::MuxPwm<'static, nrf52833::pwm::Pwm>,
17//!     capsules::virtual_pwm::MuxPwm::new(&base_peripherals.pwm0)
18//! );
19//! let virtual_pwm_buzzer = static_init!(
20//!     capsules::virtual_pwm::PwmPinUser<'static, nrf52833::pwm::Pwm>,
21//!     capsules::virtual_pwm::PwmPinUser::new(
22//!         mux_pwm,
23//!         nrf52833::pinmux::Pinmux::new(SPEAKER_PIN as u32)
24//!     )
25//! );
26//! virtual_pwm_buzzer.add_to_mux();
27//!
28//! let virtual_alarm_buzzer = static_init!(
29//!     capsules::virtual_alarm::VirtualMuxAlarm<'static, nrf52833::rtc::Rtc>,
30//!     capsules::virtual_alarm::VirtualMuxAlarm::new(mux_alarm)
31//! );
32//! virtual_alarm_buzzer.setup();
33//!
34//! let pwm_buzzer = static_init!(
35//!     capsules::buzzer_pwm::PwmBuzzer<
36//!         'static,
37//!         capsules::virtual_alarm::VirtualMuxAlarm<'static, nrf52833::rtc::Rtc>,
38//!         capsules::virtual_pwm::PwmPinUser<'static, nrf52833::pwm::Pwm>,
39//!     >,
40//!     capsules::buzzer_pwm::PwmBuzzer::new(
41//!         virtual_pwm_buzzer,
42//!         virtual_alarm_buzzer,
43//!         capsules::buzzer_pwm::DEFAULT_MAX_BUZZ_TIME_MS,
44//!     )
45//! );
46//!
47//! pwm_buzzer.set_client(buzzer);
48//!
49//! virtual_alarm_buzzer.set_alarm_client(pwm_buzzer);
50//!
51//! ```
52
53use core::cmp;
54
55use kernel::hil;
56use kernel::hil::buzzer::BuzzerClient;
57use kernel::hil::time::Frequency;
58use kernel::utilities::cells::OptionalCell;
59use kernel::ErrorCode;
60
61/// Standard max buzz time.
62pub const DEFAULT_MAX_BUZZ_TIME_MS: usize = 5000;
63
64pub struct PwmBuzzer<'a, A: hil::time::Alarm<'a>, P: hil::pwm::PwmPin> {
65    /// The underlying PWM generator to make the buzzer buzz.
66    pwm_pin: &'a P,
67    /// Alarm to stop the PWM after some time.
68    alarm: &'a A,
69    /// Max buzz time.
70    max_duration_ms: usize,
71    /// The client currently using the service capsule.
72    client: OptionalCell<&'a dyn BuzzerClient>,
73}
74
75impl<'a, A: hil::time::Alarm<'a>, P: hil::pwm::PwmPin> PwmBuzzer<'a, A, P> {
76    pub fn new(pwm_pin: &'a P, alarm: &'a A, max_duration_ms: usize) -> PwmBuzzer<'a, A, P> {
77        PwmBuzzer {
78            pwm_pin,
79            alarm,
80            client: OptionalCell::empty(),
81            max_duration_ms,
82        }
83    }
84}
85
86impl<'a, A: hil::time::Alarm<'a>, P: hil::pwm::PwmPin> hil::buzzer::Buzzer<'a>
87    for PwmBuzzer<'a, A, P>
88{
89    fn set_client(&self, client: &'a dyn BuzzerClient) {
90        self.client.replace(client);
91    }
92
93    fn buzz(&self, frequency_hz: usize, duration_ms: usize) -> Result<(), ErrorCode> {
94        let duration_ms_cmp = cmp::min(duration_ms, self.max_duration_ms);
95        self.pwm_pin
96            .start(frequency_hz, self.pwm_pin.get_maximum_duty_cycle() / 2)?;
97
98        // Set an alarm for the given duration.
99        let interval = (duration_ms_cmp as u32) * <A::Frequency>::frequency() / 1000;
100        self.alarm
101            .set_alarm(self.alarm.now(), A::Ticks::from(interval));
102        Ok(())
103    }
104
105    fn stop(&self) -> Result<(), ErrorCode> {
106        // Disarm the current alarm and instantly fire another.
107        self.alarm.disarm()?;
108        // This method was used to reduce the size of the code.
109        self.alarm.set_alarm(self.alarm.now(), A::Ticks::from(0));
110        Ok(())
111    }
112}
113
114impl<'a, A: hil::time::Alarm<'a>, P: hil::pwm::PwmPin> hil::time::AlarmClient
115    for PwmBuzzer<'a, A, P>
116{
117    fn alarm(&self) {
118        // Stop the pin output and signal that the buzzer has finished
119        // playing.
120        self.client
121            .map(|buzz_client| buzz_client.buzzer_done(self.pwm_pin.stop()));
122    }
123}
capsules_extra/buzzer_pwm.rs

capsules_extra/
buzzer_pwm.rs
