Re: [ECOS] Cortex-M1/3 SysTick/RTC

["simon dot kallweit at intefo dot ch" <simon dot kallweit at intefo dot ch>]

Andrew Lunn wrote:
> SysTick is great for the eCos clock.
>
> You could do a very simple HAL_DELAY_US(us) which only has 1ms
> resolution. Not great, but it at least will work and gets you going.
>
> Or you can go for implementation 3, using a 1ms calibration time
> derived from the SysTick. 
>   

I have implemented the real-time-clock using the SysTick. It should work 
pretty well as I found out with some simple tests. I have also used the 
SysTick counter for a default implementation of the HAL_DELAY_US 
function, which should be pretty accurate (0.01 us accuracy with 72mhz 
clock). What bothers me though, is how to implement the SysTick 
interrupt. It belongs to the default exception vectors of the Cortex 
core. So I guess the architecture should define this ISR vector, but 
normally these go into the variant or platform packages. How can we do that?

Simon

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