[Skimmertalk] Red Pitaya set up with N6TV's instructions

[Bob Wilson, N6TV]

For Alpine Linux running on the Red Pitaya, try this version of the
temperature / voltage display script that I just uploaded (it was modified
by Pavel Demin to work in the ash shell):

http://www.kkn.net/~n6tv/xadc-new.sh

According to the FPGA data sheet, 85° C. is the absolute maximum
temperature supported by the FPGA.  Of course, heat is the enemy of all
electronics (this is why so many un-cooled QS1Rs like mine eventually
failed), so the cooler you can keep it, the better.

To cool the aluminum case, I simply mounted a 30mm 5V fan a few mm above
the top center of the case, right above the center of the heat sink.  That
required drilling and tapping some small mounting holes.

Since there is no room inside, and no cooling holes, it's about the only
place to put it.  You can then carefully run two thin power wires into a
gap on the left side of the case to bring them inside, then carefully
solder or somehow connect those two wires to the power pins next to the
Ethernet connector (the positive pin is closest to the center of the
case).  This Red Pitaya is currently running 66° C with the ambient room
temperature around 24° C.

The Red Pitaya next to it in a plastic case with a similar fan on top is
running 58° C.

When the room got very warm on a hot day (28° C.) I saw the temperature of
the Red Pitay in the metal case get as high as 78° C., which was too close
to the limit IMHO.  After adding the fan on top, the most I've seen is
around 70° C.

73,
Bob, N6TV

On Wed, Oct 4, 2017 at 2:19 PM, <dd5xx at web.de> wrote:

> > I tried the script Bob mentioned on his tutorial, but unfortunately it
> did not work on the latest Alpine OS SDcard image.
>
> Hello again,
>
> I looked into Bobs' script and I think I know why it fails when I try to
> run it:
> if one use Pavel's latest SDcard image which runs GNU/Linux Alpine the
> default shell is "ASH" and not "bash". You can check it with the shell
> prompt command "echo $SHELL". So you need to modify Bob's shebang (1st line
> in script xadc.sh) and change it to
>
> #!/bin/ash
>
> Because ASH shell is using other syntax the following voltage function
> fails, too. But I don't care about the voltages at the moment so I
> commented out these lines. The whole script looks like that:
>
> ----BEGIN-----
>
> #!/bin/ash
>
> # path to IIO device
> XADC_PATH=/sys/bus/iio/devices/iio:device0
>
> ############################################################
> ####################
> # temperature
> ############################################################
> ####################
>
> OFF=`cat $XADC_PATH/in_temp0_offset`
> RAW=`cat $XADC_PATH/in_temp0_raw`
> SCL=`cat $XADC_PATH/in_temp0_scale`
>
> FORMULA="(($OFF+$RAW)*$SCL)/1000.0"
> VAL=`echo "scale=2;${FORMULA}" | bc`
> echo "in_temp0 = ${VAL} ..C"
>
> -----END------
>
> I am running it now with "watch ./xadc.sh" so the script is invoked each 2
> seconds and I see the actual temperature. In the background the task
> "sdr_transceiver_hpsdr" is running so I will monitor the temperature for a
> while. After 10 minutes it is ~66 ° C. I am using the aluminium case
> without any fan. So in my humble opinion this should be sufficient,
> shouldn't it ?
>
> Best 73
> Saki, DD5XX
>
>
>
> Gesendet: Mittwoch, 04. Oktober 2017 um 22:37 Uhr
> Von: "Wes Cosand" <wes.cosand at gmail.com>
> An: dd5xx at web.de
> Cc: skimmertalk <skimmertalk at contesting.com>
> Betreff: Re: [Skimmertalk] Red Pitaya set up with N6TV's instructions
>
> Hi Saki:
>
> I am using an old 12 volt power supply from a dead laptop to power my
> fan.  It is quite noisy but it is in the basement.  I am no expert but the
> FPGA chip gets hot, even with the aluminum, case as Bob has documented.  I
> would be hesitant to run it on 6 bands without a fan.
>
> But you can measure the temperature yourself with the Linux script that
> Bob documents on his web page.
>
> Wes WZ7I
>