[time-nuts] wifi with time sync
jimlux at earthlink.net
Sat Jan 14 19:04:42 EST 2017
On 1/14/17 3:32 PM, Bob Camp wrote:
>> On Jan 14, 2017, at 5:29 PM, Scott Stobbe <scott.j.stobbe at gmail.com> wrote:
>> I don't think wifi is ever going to be a real-time system, as it shares the
>> ether with all other ISM devices. That said even 1 ms of variation is still
>> 4 orders of magnitude greater than the actual time of flight.
>> The precision time aspect will most certainly be done in hardware, even if
>> it's just as simple as a timestamp of receiving the beacon frame.
> My concern *is* that it’s going to be like 1588 in that respect. Off we all have
> to buy new time stamping hardware. Until that’s all up and running
> you don’t get the new timing stuff. Based on what I see, there’s not a lot
> of hope for it otherwise.
just rummmaging through some datasheets..
I see that for the SG922-0007 (a WiFi module with AT command set) they
do list a value that can be read for "timestamp of last received packet"
and "timestamp of last transmitted packet"
As to what those might mean??
A Copperhead WiFi shield for Arduino has a microchip MRF24WB0MA on it
(it's a few years old, I think it's been replaced by something newer)
Microchip doesn't make it easy to find the SPI interface details, though.
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