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#apertus IRC Channel Logs

2020/04/07

Timezone: UTC


03:15
Spirit532
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03:20
Bertl_oO
vup: yes, what's the plan there?
04:05
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05:09
Bertl_oO
off to bed now ... have a good one everyone!
05:09
Bertl_oO
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BAndiT1983|away
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11:06
Bertl_zZ
changed nick to: Bertl
11:06
Bertl
morning folks!
11:50
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12:22
vup
Bertl: well we want to test up to which frequencies we can reliably use a connector
12:31
Bertl
thought so, but what's the plan here?
12:32
Bertl
some kind of loopback module?
12:32
Bertl
or a test board which uses the connector in question or something completely different?
13:46
vup
Bertl: well we are starting with the 100mil headers that are already present on the current micro, using a wire bridge to loopback one pin to another
13:54
Bertl
wire bridge?
13:54
Bertl
you mean a cable?
13:59
vup
yeah
13:59
Bertl
it will be tricky to match the 50/100Ohm there
14:00
vup
well the connector itself also doesn't match 50/100Ohm, so keeping the cable short shouldn't make it much worse i would think
14:00
Bertl
really depends on the impedance changes
14:01
vup
yeah, this isn't really meant as a decisive test for it not working
14:02
vup
but if it works with that setup, it should definitely work with a more proper setup
14:02
Bertl
hard to tell, could work by accident as well
14:02
vup
how so?
14:02
Bertl
what exactly is the goal of the test?
14:03
vup
well mainly figuring out if we can just use 100mil headers for the sensor connection
14:04
Bertl
okay, so the connection goes 'main PCB' - 100mil header - 'sensor PCB'
14:04
vup
yes
14:04
Bertl
and the data transfer is typically in the other direction, yes?
14:04
vup
for most sensor I would imagine so
14:05
vup
the cmv12k has a high speed clock input, right?
14:05
Bertl
okay, so the best setup would be to create a dummy senor PCB which consists of a properly routed 'loop' from I/Os of one side of the connector to the other
14:05
Bertl
e.g. if you have 8 LVDS pairs for sensor connection
14:06
Bertl
create loops between the outer most down to the innermost
14:06
Bertl
all properly routed on the dummy sensor board
14:07
Bertl
this way you know when the loopback test works at a given frequency, the sensor will be fine and in safe range
14:07
Bertl
(because you traverse the connector twice for every loop)
14:07
vup
yes that sounds like a good setup
14:08
vup
the hope was we can forgo the need of the dummy sensor board if it works with the current setup
14:08
Bertl
well, you can test that as well, but I wouldn't draw too many conclusions from that
14:10
Bertl
capacitance and inductance might just cancel each outher out at the freqeuncy you test with
14:10
vup
hmm yeah maybe
14:11
vup
I was planning on doing a frequency sweep anyways (roughly 250MHz DDR -> 500MHz DDR)
14:11
Bertl
okay, that will definitely get better results
14:13
vup
using that I think we should be able to rule out most accidents
14:13
Bertl
could work
14:13
vup
but i guess we will just have to see how the results look like and then decide if we want to test it with a dummy sensor board or not
14:13
Bertl
definitely let me know how it goes :)
14:13
vup
yes, will do
14:33
BAndiT1983
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16:00
Bertl
off for now ... bbl
16:00
Bertl
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BAndiT1983|away
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Bertl_oO
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BAndiT1983
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