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rust-raspberrypi-OS-tutorials/09_delays
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Andre Richter 0d75a8eaf3
Use aarch64-unknown-none target in nightly 🎉 
We have a generic target for writing bare-metal code
for 64-bit ARM architectures in upstream Rust now.

Use it to get rid of the fully custom target spec.

\o/
2018-08-19 23:42:24 +02:00
..
.cargo Use aarch64-unknown-none target in nightly 🎉 2018-08-19 23:42:24 +02:00
raspi3_boot Sync with the newest Embedonomicon 2018-08-12 16:41:45 +02:00
src Use correct sequence of MMIO timer reads 2018-08-12 17:06:30 +02:00
Cargo.lock Sync with the newest Embedonomicon 2018-08-12 16:41:45 +02:00
Cargo.toml Sync with the newest Embedonomicon 2018-08-12 16:41:45 +02:00
kernel8.img Use aarch64-unknown-none target in nightly 🎉 2018-08-19 23:42:24 +02:00
link.ld Sync with the newest Embedonomicon 2018-08-12 16:41:45 +02:00
Makefile Use aarch64-unknown-none target in nightly 🎉 2018-08-19 23:42:24 +02:00
README.md Add tutorial 0A_power 2018-04-23 22:05:22 +02:00

README.md

Tutorial 09 - Delays

It is very important to wait precise amounts of time while you are interfacing with low level hardware. In this tutorial, we'll cover thee ways. One is CPU frequency dependent (and useful if wait time is given in CPU clock cycles), the other two are µs based.

delays.rs

delays::wait_cycles(cyc: u32) this is very straightforward, we execute the nop instruction n times.

delays::wait_msec(n: u32) this implementation uses ARM system registers (available on all AArch64 CPUs).

delays::SysTmr::wait_msec_st(&self, n: u64) is a BCM specific implementation, which uses the System Timer peripheral (not available on qemu).

uart.rs

We can now conveniently use delays::wait_cycles() in Uart::init().

main.rs

We test our different wait implementations.