On 10/6/11 4:24 PM, Magnus Danielson wrote:
Consider that you have 7 digits of time-stamp value and 8 digits of hex
code for time-stamped inputs and a carrige return, you need to output 16
bytes. Considering that it takes 32 read-outs a second in peak. This
means 512 bytes a second or a rate of 5120 baud needed, so 9600 baud
output will do just fine. The time-stamper clock can count in BCD to
make conversion cheap (and easy to code, just slab 0010 on top of
digits). A 64 bit wide FIFO is needed to store time-stamps, as they can
come at high burst rate but low average flow.
It's doable and not too much work to cook up. I did something similar
before, but I just can't find the code lying around. Sad, since it had
the serial transmitt code and FIFO stuff more or less what we need.
That's basically what I was thinking.. 9600 bps is also slow enough
that you can do something on the receiving end like open the file, add a
line, close the file, so it makes rolling over files every hour or
whatever easy.
The experiment I have in mind will last about 2 months, with the batch
of oscillators cycling in temperature either on a 100 minute cycle or a
24 hour cycle. (Low orbit or earth/mars rotation period)
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