Re: Timing differences before / after starting scheduler

[Stanislav Meduna <stano@xxxxxxxxxx>]

On 22.08.2010 15:45, Tim Jaacks wrote:

> I am using eCos on an LPC2378, running at 72MHz. Some driver I have
> implemented reads out eight double words from a CPU FIFO, using eight
> equal subsequent lines of C-code.

Which FIFO? The UART FIFO is 16 bytes, why 8 DWORDs? In the
case you mean 8 bytes (half a buffer), 8 bytes in 17 us means
3,75 Mbps. I don't know the LPC2378, but as far as I can see
the UART is considered a low-speed interface and is connected
to the APB. Maybe you are stretching the hardware a bit?

> 1. Can anybody explain to me, what eCos is doing within these 12
> microseconds, which the instructions take longer now?

If disabling all interrupts doesn't help I'd guess other activity
on the bus - interrupt being generated and sent to the processor,
maybe DMA, ...

-- 
                                   Stano

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