[beagleboard] Re: spi / shiftout.js in 2017-03-19 image

[Jeff Albrecht]

On Tuesday, July 11, 2017 at 6:56:07 PM UTC-7, Jeff Albrecht wrote:
>
> On Friday, July 7, 2017 at 1:53:10 PM UTC-7, Jeff Albrecht wrote:
>
> [...]
>> Are there any other changes that I may have missed? Suggestions?
>>
>
> Regarding the SPI test in Exploring BeagleBone Black. Got it, works on my 
> machine now! 
>

Ack!

apt-get update, apt-get upgrade broke my config-pin :-( Reading this thread 
P9_25_pinmux 
not found in /sys/devices/platform/ocp ?  
I, 
once again, flash my BBB. spi and config-pin working again and survives 
apt-get upgrade.

-- 
For more options, visit http://beagleboard.org/discuss
--- 
You received this message because you are subscribed to the Google Groups 
"BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to beagleboard+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/beagleboard/5432d796-929b-46e6-8970-06410fb268b9%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: [beagleboard] Re: spi / shiftout.js in 2017-03-19 image

[Jeff Albrecht]

On Tuesday, July 11, 2017 at 8:25:54 PM UTC-7, William Hermans wrote:

Additionally, this could very well be a Nodejs bottleneck. I've personally 
> experienced first hand how slow Nodejs really is when working with fast 
> moving code. I notice the title "shiftout.js" but you're also talking about 
> C too. So maybe you're using a hybrid of the two ? A bit confusing, but 
> maybe some clarity on the subject is deserved ? 
>
>
In hindsight discussing the spi in .css and the shiftout in .js in the same 
message may have been a bit confusing. _sorry about that_

-- 
For more options, visit http://beagleboard.org/discuss
--- 
You received this message because you are subscribed to the Google Groups 
"BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to beagleboard+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/beagleboard/7cc18c52-4c66-47a6-9cad-2c6ca3ae8194%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: [beagleboard] Re: spi / shiftout.js in 2017-03-19 image

[William Hermans]

On Tue, Jul 11, 2017 at 8:17 PM, William Hermans  wrote:

> SPI is notoriously finicky when it comes to high speed, and noise. Since
> I'm not an EE, I could not say much more than that. Typically though, from
> what I understand, traces can not be very long.
>

Additionally, this could very well be a Nodejs bottleneck. I've personally
experienced first hand how slow Nodejs really is when working with fast
moving code. I notice the title "shiftout.js" but you're also talking about
C too. So maybe you're using a hybrid of the two ? A bit confusing, but
maybe some clarity on the subject is deserved ?

Using my own  javascript library, which pretty much just encapsulates the
sysfs file entries. When toggling GPIO, I've noticed it peters off at about
1Khz, or slightly less. That's just using a simple XOR binary operation.
Arguably, using /dev/mem/ and mmap() would be faster, but the speed of
scripting language code is alway going ot be a bottle neck. First, because
it's an interpreted language, and second, because the "binary" size is huge
compared to something like C. It's going ot be a lot slower.

-- 
For more options, visit http://beagleboard.org/discuss
--- 
You received this message because you are subscribed to the Google Groups 
"BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to beagleboard+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/beagleboard/CALHSORo6F7B9jmKH0rvJYgyK1%3DRs6jsZ_YPxMyxK526%2B7XWoZw%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.

Re: [beagleboard] Re: spi / shiftout.js in 2017-03-19 image

[William Hermans]

SPI is notoriously finicky when it comes to high speed, and noise. Since
I'm not an EE, I could not say much more than that. Typically though, from
what I understand, traces can not be very long.

-- 
For more options, visit http://beagleboard.org/discuss
--- 
You received this message because you are subscribed to the Google Groups 
"BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to beagleboard+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/beagleboard/CALHSORpPbyiUv5tmJK%3DcuBHePzitf746DTsuor8RJMupGtQC1Q%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.

[beagleboard] Re: spi / shiftout.js in 2017-03-19 image

[Jeff Albrecht]

On Friday, July 7, 2017 at 1:53:10 PM UTC-7, Jeff Albrecht wrote:

[...]
> Are there any other changes that I may have missed? Suggestions?
>

Regarding the SPI test in Exploring BeagleBone Black. Got it, works on my 
machine now! Thank you William and Gaurav for your input. It turned out 
that the default clock speed in the spi595.c code was to fast for the 
74HC595N I am using. I changed it down from 1mhz to 10khz. I powered it 
from 3.3vdc. If I'm reading the data sheet correctly it looks like it 
should be able to do 4mhz at 2vdc. Perhaps this chip was a reject or 
counterfeit? Perhaps the setup on a solder-less breadboard had some 
negative effect. Or???






   // transfer.speed_hz = 100;//the speed in Hz
   transfer.speed_hz = 1;//the speed in Hz



# in lieu of loading a device overlay I used config-pin to configure SPI. - 
Thanks Drew pdp7

$ cat /etc/dogtag
$ BeagleBoard.org Debian Image 2017-03-19
$ uname -a
$ Linux beaglebone 4.4.54-ti-r93 #1 SMP Fri Mar 17 13:08:22 UTC 2017 armv7l 
GNU/Linux

$ config-pin -l P9.17 #SPI0_CS
$ config-pin -l P9.18 #SPI0_D1
$ config-pin -l P9.22 #SPI0_SCLK
$ config-pin -l P9.21 #SPI0_D0

$ ./spi595


Along the way I learned how to use the SPI decoders on my Saleae logic 8 
and Rigol DS1054z








-- 
For more options, visit http://beagleboard.org/discuss
--- 
You received this message because you are subscribed to the Google Groups 
"BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to beagleboard+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/beagleboard/abadd68f-63b4-4c59-aff0-31808c257478%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[beagleboard] Re: spi / shiftout.js in 2017-03-19 image

[Gaurav S]

Also note that Derek Molly's code does not set all parameters in the 
structure spi_ioc_transfer.. Bad/undefined values can cause SPI to die. 
Ensure you set all fields to have valid values. 

struct spi_ioc_transfer 
 {
__u64    
tx_buf ;
__u64    
rx_buf ;

__u32    
len;
__u32    
speed_hz;

__u16    
delay_usecs;
__u8  
bits_per_word 
;
__u8  
cs_change;
__u8  
tx_nbits;
__u8  
rx_nbits;
__u16    
pad ;

/* If the contents of 'struct spi_ioc_transfer' ever change  * 
incompatibly, then the ioctl number (currently 0) must change;* ioctls 
with constant size fields get a bit more in the way of * error checking 
than ones (like this) where that field varies. *   * NOTE: struct 
layout is the same in 64bit and 32bit userspace. */};


On Friday, July 7, 2017 at 3:53:10 PM UTC-5, Jeff Albrecht wrote:
>
> Perhaps a year or more ago I finished Part I and II of Derek Molloy's 
> excellent book;  "Exploring Beaglebone" At the time I specifically recall 
> successfully running the shiftout.js in the cloud9 ide and the spi595.c 
> from the book. Flash forward to now I'm returning to finish part III 
> specifically PRUs but thought it prudent to review a bit.
>
> I flash my BBB with bone-debian-8.7-iot-armhf-2017-03-19-4gb.img.xz
>
> jeffa@beaglebone:~$ cat /etc/dogtag
> BeagleBoard.org Debian Image 2017-03-19
> jeffa@beaglebone:~$ uname -a
> Linux beaglebone 4.4.54-ti-r93 #1 SMP Fri Mar 17 13:08:22 UTC 2017 armv7l 
> GNU/Linux
> jeffa@beaglebone:~$
>
> While working with the spi595.c I check the slots. I'm not positive but it 
> looks like the way to configure pins now is with c*ape-universaln*. I 
> also find a handy gist 
>  from Drew 
> @pdp7 where I learn about *config-pin. *I also try loading the BB-SPIDEV0 
> and the ADAFRUIT-SPI0 in /etc/default/capemgr and rebooting.
>
> jeffa@beaglebone:~$ cat /sys/devices/platform/bone_capemgr/slots
>  0: PF  -1
>  1: PF  -1
>  2: PF  -1
>  3: PF  -1
>  4: P-O-L-   0 Override Board Name,00A0,Override Manuf,cape-universaln
> jeffa@beaglebone:~$
>
> Not getting the blinkin' lighting with the spi595.c test code from the 
> book, I try the simpler shiftout.js bit banging (not spi) example from the 
> BBB documentation  
> and cloud9 ide. Nope. I write a quick bonescript .js to test my GPIOs by 
> toggling low/high. They're good.  I hook up my oscilloscope to see that I'm 
> only getting the latch (on channel 3). Where is the clock and the serial 
> in? 
>
> Are there any other changes that I may have missed? Suggestions?
>
>
> 
>
>

-- 
For more options, visit http://beagleboard.org/discuss
--- 
You received this message because you are subscribed to the Google Groups 
"BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to beagleboard+unsubscr...@googlegroups.com.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/beagleboard/a0a154ad-cb7e-467c-9ec7-3d5ae8f2d737%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.