add board::delay

This commit is contained in:
Astro 2019-08-08 00:37:29 +02:00
parent f04bbd8726
commit 9c7ca0df87
2 changed files with 77 additions and 0 deletions

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@ -0,0 +1,76 @@
use embedded_hal::blocking::delay::{DelayMs, DelayUs};
use cortex_m::peripheral::syst::SystClkSource;
use cortex_m::peripheral::SYST;
use tm4c129x::CorePeripherals;
/// precision internal oscillator
const PIOSC: u32 = 16_000_000;
pub struct Delay {
syst: SYST,
}
impl Delay {
pub fn new() -> Self {
let mut cp = unsafe { tm4c129x::CorePeripherals::steal() };
let mut syst = cp.SYST;
// PIOSC
syst.set_clock_source(SystClkSource::External);
syst.disable_interrupt();
Delay { syst }
}
}
impl DelayMs<u32> for Delay {
fn delay_ms(&mut self, ms: u32) {
self.delay_us(ms * 1_000);
}
}
impl DelayMs<u16> for Delay {
fn delay_ms(&mut self, ms: u16) {
self.delay_ms(u32::from(ms));
}
}
impl DelayMs<u8> for Delay {
fn delay_ms(&mut self, ms: u8) {
self.delay_ms(u32::from(ms));
}
}
impl DelayUs<u32> for Delay {
fn delay_us(&mut self, us: u32) {
// The SysTick Reload Value register supports values between 1 and 0x00FFFFFF.
const MAX_RVR: u32 = 0x00FF_FFFF;
let mut total_rvr = us * (PIOSC / 1_000_000);
while total_rvr != 0 {
let current_rvr = total_rvr.min(MAX_RVR);
self.syst.set_reload(current_rvr);
self.syst.clear_current();
self.syst.enable_counter();
// Update the tracking variable while we are waiting...
total_rvr -= current_rvr;
while !self.syst.has_wrapped() {}
self.syst.disable_counter();
}
}
}
impl DelayUs<u16> for Delay {
fn delay_us(&mut self, us: u16) {
self.delay_us(u32::from(us))
}
}
impl DelayUs<u8> for Delay {
fn delay_us(&mut self, us: u8) {
self.delay_us(u32::from(us))
}
}

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@ -3,6 +3,7 @@ use tm4c129x;
mod gpio;
mod softspi;
mod delay;
const LED1: u8 = 0x10; // PK4