---------- Forwarded message ----------
From: Gonenc Ulker (Alumni) <[email protected]>
Date: 2014-10-06 10:17 GMT+03:00
Subject: Beaglebone-fs.write spidev issue
To: [email protected]
Cc: "Gorkem Turk (Alumni)" <[email protected]>, Alican Kızılkaya <
[email protected]>
Hi, Jason
this is Gonenc from Mechatronics Department of Sabanci University
hope you are fine
We have been using Beaglebone White for remotely controlling-tracking our
solar inverter system over internet
We are planning to connect afew devices over SPI, so decided to use the
already enabled */dev/spidev2.0 (Angstrom 3.2.34)*
We are working with CloudIDE and bonescript
We can write the SPI module using
spi_write = exports.spi_write = function(spi_message)
{
var muxfile=fs.openSync("/dev/spidev2.0","w");
fs.writeSync(muxfile,spi_message);
fs.closeSync(muxfile);
}
BUT THE PROBLEM IS:
when
spi_message=0x01 ==> it gives *0x31* as SPI HW output
spi_message=0x02 ==> it gives *0x32* as SPI HW output
....
Looks like taking it as char and not as integer
This is most probably due to *fs.write* used with strings
So instead tried this from shell for various hex numbers
for i in {1..20000}
do
echo -ne "\x87" > /dev/spidev2.0
done
And it works correctly for valueas of "\x00" to "\xFF" as expected
So we decided to apply the same to *fs.write*
*fs.write("\x00") to fs.wrte("\x7F") //* we are *OK from 0 to 127*
but than starts extended ascii part and *from 128-255 we can't get correct
values*
-Can we call echo command from bonescript directly
-Can we pass integer arguements to spidev using *fs.write *or any command
else
-Or any other alternative method you can offer for more "flexible"
opeartion of SPI from Cloud9
and that can provide spi_module access / easy setting of spi_clock_speed...
without dealing with Kernel stuff :)
thanks in advance
--
Gonenc Ulker
MSc Mechatronics Engineering Program
Sabanci University
Faculty of Engineering and Natural Sciences
Tuzla 34956, Istanbul, Turkey
--
Gonenc Ulker
MSc Mechatronics Engineering Program
Sabanci University
Faculty of Engineering and Natural Sciences
Tuzla 34956, Istanbul, Turkey
--
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