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Andre Richter 27a5f64156 Dockcross binaries path changed		2018-05-16 00:28:21 +02:00
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raspi3_glue	Add timer tutorial	2018-04-19 18:46:24 +02:00
src	Add tutorial 0A_power	2018-04-23 22:05:22 +02:00
aarch64-raspi3-none-elf.json	Add timer tutorial	2018-04-19 18:46:24 +02:00
Cargo.lock	Add timer tutorial	2018-04-19 18:46:24 +02:00
Cargo.toml	Add timer tutorial	2018-04-19 18:46:24 +02:00
kernel8.img	Add timer tutorial	2018-04-19 18:46:24 +02:00
link.ld	Add timer tutorial	2018-04-19 18:46:24 +02:00
Makefile	Dockcross binaries path changed	2018-05-16 00:28:21 +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.