Re: [lwip-users] raw lwIP on uC, timer or Ethernet Interrupt?

[Pomeroy, Marty]

Tamas

To achieve 10 microsecond resolution across multiple boxes would require
a sync mechanism other than just ethernet packets arriving.  PTP
(Precision time protocol, I assume) or a GPS chip could keep the timing
sync, and then a packet telling all boxes what time in the future to
start.

BTW - it sounds like you are polling the ethernet input.  I personally
dislike polling when an interrupt is available.  But you cannot rely on
the timing of packets arriving.

Marty


-----Original Message-----
From: address@hidden
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Behalf Of m_tamas
Sent: Monday, May 14, 2012 3:36 AM
To: address@hidden
Subject: [lwip-users] raw lwIP on uC, timer or Ethernet Interrupt?


Hi,

I would like to develop an Ethernet device with an ARM uC. I am using a
raw lwIP on it. Latter I would like to use more devices which are
connected to a switch. A PC which is also connected to the switch will
send a broadcast message which starts these devices. My problem is that
the devices should start the working at the same time. The starting time
difference between the devices should be under 10 uSec. Is it possible
without PTP? Can you give me a development direction? My current example
program work with a timer. The timer periodically 10ms trigger an
Ethernet interrupt, but this 10 ms cause my starting problem. Can i use
a simple Ethernet interrupt instead of timer?

Best regards,
Tamas
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