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by theoldwizard1
Thu Sep 19, 2019 10:18 pm
Forum: Bare metal, Assembly language
Topic: BCM2711B0
Replies: 33
Views: 3185

Re: BCM2711B0

Well, it has been about 10 weeks since I kicked off this thread and I still have not found and datasheets or other documentation on the BCM2711B0 ! Anyone else ? One thing I am very curious about is if there more than 1 channel of PCIe ? Segue - Does Broadcomm actually directly sell any of the other...
by theoldwizard1
Mon Jul 22, 2019 5:28 am
Forum: Bare metal, Assembly language
Topic: Reserving cores for bare-metal programs - interupts
Replies: 36
Views: 3525

Re: Reserving cores for bare-metal programs - interupts

A very interesting project ! Related to this is the various cache levels, delays for line fills and of course delays when all caches are missed. I would love to see a write up on this !
by theoldwizard1
Fri Jul 12, 2019 5:32 pm
Forum: Bare metal, Assembly language
Topic: BCM2711B0
Replies: 33
Views: 3185

Re: BCM2711B0

In brief summation so far: We still do not know anything about the Ethernet Controller. According to Raspi.tv , the Pi 4 uses a BCM54213. If this was a separate chip, I'm sure someone would have found it by now, so it is likely integrated into the SoC. EDIT : Found similar on Hackaday
by theoldwizard1
Wed Jul 03, 2019 1:44 pm
Forum: Bare metal, Assembly language
Topic: BCM2711B0
Replies: 33
Views: 3185

Re: BCM2711B0

Yes, it is the first Pi with PCIe. It should be noted that it only has one lane and that is in use. That means no simple option for adding more PCIe peripherals. Yes, but it proves Broadcom knows how to do it on a SoC. More lanes is basically finding more pins on the chip and a few more "pico acres...
by theoldwizard1
Wed Jul 03, 2019 12:39 pm
Forum: Bare metal, Assembly language
Topic: BCM2711B0
Replies: 33
Views: 3185

Re: BCM2711B0

One other bit of information we have is that the USB Host Controller is a Via Labs VL805. I am just starting to look to see if there is any good information on programming for this controller. Thanks for the info on the USB Host controller. There certainly is not any documentation about the VL805 o...
by theoldwizard1
Wed Jul 03, 2019 12:25 pm
Forum: Bare metal, Assembly language
Topic: BCM2711B0
Replies: 33
Views: 3185

Re: BCM2711B0

I am VERY interested in the PCIe capabilities of that chip ! Is this the first RPi that had a SoC with PCIe ? It should be noted that microSD Express is now the logical next step to replace the current microSD card. MicroSD Express takes one PCIe lane, uses NVMe and has a theoretical transfer rate o...
by theoldwizard1
Wed Jul 03, 2019 1:29 am
Forum: Bare metal, Assembly language
Topic: BCM2711B0
Replies: 33
Views: 3185

BCM2711B0

I have been out of the embedded system development for almost 20 year now, but prior to that, I was DEEPLY INVOLVED. Clearly much has changed but I still like to read documentation on the "guts" of new SoCs. Everything from the instruction set and programmers model to all of the on chip "interfaces"...
by theoldwizard1
Thu Nov 22, 2018 7:27 pm
Forum: Bare metal, Assembly language
Topic: FAST RAM
Replies: 10
Views: 2414

Re: FAST RAM

BTW I did the same thing I bought a small FPGA kickstarter kit to do my storage scope. How far have you gotten on the project ? Would you care to share ? The Rigol and other inexpensive bench scopes are truly amazing ! The portable 'scope market needs a serious "kick in the butt" ! PicoScopes are u...
by theoldwizard1
Thu Nov 22, 2018 7:15 pm
Forum: Bare metal, Assembly language
Topic: FAST RAM
Replies: 10
Views: 2414

Re: FAST RAM

If I can not read the GPIO pins and write them to shared RAM every 100nsec (50nsec better) then I should abandon this approach and would have to use a FPGA. Just checked with a guy in the office, 400ns would appear to be achievable, but probably not much lower than that as there's a lot of bus fluf...
by theoldwizard1
Thu Nov 22, 2018 1:25 pm
Forum: Bare metal, Assembly language
Topic: FAST RAM
Replies: 10
Views: 2414

Re: FAST RAM

If I can not read the GPIO pins and write them to shared RAM every 100nsec (50nsec better) then I should abandon this approach and would have to use a FPGA.
by theoldwizard1
Thu Nov 22, 2018 7:41 am
Forum: Bare metal, Assembly language
Topic: FAST RAM
Replies: 10
Views: 2414

Re: FAST RAM

Obviously you already got to the point of successful boot, successful enabling of the CPU Caches, and successfully turned on the MMU with a valid page table. As such you need little else, as long as your code and data is small enough it will stay in the caches, nothing more to it, so long as that r...
by theoldwizard1
Thu Nov 22, 2018 2:15 am
Forum: Bare metal, Assembly language
Topic: FAST RAM
Replies: 10
Views: 2414

FAST RAM

None of the Pi board (or more properly none of their MCUs) have any on chip RAM other than L1 and L2 caches. If I have a process that is "locked" to one core (using sched_setaffinity) that is simply reading GPIO pins and writing them to a circular buffer, is there anyway to "lock" the L2 cache contr...
by theoldwizard1
Thu Nov 22, 2018 2:06 am
Forum: Raspbian
Topic: A real time process on a multi-cpu RPi
Replies: 0
Views: 884

A real time process on a multi-cpu RPi

I am think of a application that would require read a large number of GPIO pin on a Compute Module IO Board and writing them to a circular buffer as quickly as possible. The process would be an infinite loop. Read pins. Write buffer. Loop Has anyone had success using sched_setaffinity ? I have done ...
by theoldwizard1
Tue Nov 20, 2018 2:03 pm
Forum: Raspbian
Topic: Locking a "task" to a core
Replies: 1
Views: 1125

Locking a "task" to a core

I am re-posting this here from the assembly language forum withe the (very small hope) that some over here might know a trick ! I am new to Pi, but not new to embedded design and programming. I am think of a data acquisition project. In my mind, I want a small stand alone process that would grab dat...
by theoldwizard1
Tue Nov 20, 2018 11:22 am
Forum: Bare metal, Assembly language
Topic: Locking a "task" to a processor
Replies: 2
Views: 1929

Locking a "task" to a processor

I am new to Pi, but not new to embedded design and programming. I am think of a data acquisition project. In my mind, I want a small stand alone process that would grab data from the GPIO pins and copy it to a circular buffer, shared RAM, as fast as possible. It would seem that the best way to do th...
by theoldwizard1
Tue Nov 20, 2018 5:28 am
Forum: General discussion
Topic: additional GPIO
Replies: 4
Views: 271

Re: additional GPIO

Soldering wires to the bottom of the board won't get you anywhere. But...if you go with the CM, CM3 or CM3L, you will have access to all the GPIO connections the SoC has. You'll need a carrier board, though, but since your experience is with embedded systems, that should make you feel right at home...
by theoldwizard1
Tue Nov 20, 2018 5:07 am
Forum: General discussion
Topic: additional GPIO
Replies: 4
Views: 271

additional GPIO

I am new to Raspberry Pi, but not embedded system design and programming. For obvious reasons, RPi can only bring out a limited number of the GPIO pins to a header. I need more pins and can not afford the delay of using an I²c or SPI expander. Is there any way to access the addition GPIO pins of the...
by theoldwizard1
Sun May 22, 2016 9:53 pm
Forum: Beginners
Topic: LightDM
Replies: 3
Views: 691

Re: LightDM

You see this is the problem ! I came from the world of CDE (which I will admit I never fully mastered) and desktop before that ! I have no idea what SLiM or GDM are. "LXDE" and "freedesktop" are just letters and words. Not sure what you mean by "add/remove apps from the top bar". See I don't even kn...
by theoldwizard1
Tue May 17, 2016 11:08 am
Forum: Beginners
Topic: LightDM
Replies: 3
Views: 691

LightDM

Kind of hard to call me a NOOB, but I am when is comes to LightDM ! (I haven't done any Un*x work in about 10 years, but before that I was responsible for multiple, different, commercial Unix desktops and servers.) I am looking (it seems in vane) for some very basic information on LightDM. Things li...
by theoldwizard1
Fri May 06, 2016 11:52 pm
Forum: Beginners
Topic: Light Display Manager does not start (using HDTV display)
Replies: 8
Views: 1790

Re: Light Display Manager does not start (using HDTV display

I strongly recommend any newbies (even us "old timers") to install Raspbian with NOOBS. IT WORKS ! Following the "standard" installation DOES NOT !
by theoldwizard1
Sat Apr 30, 2016 10:35 am
Forum: Beginners
Topic: Light Display Manager does not start (using HDTV display)
Replies: 8
Views: 1790

Re: Light Display Manager does not start (using HDTV display

topguy wrote:If you are still able to log in via ssh and snip out the errors from the log and post here it would probably be helpful. Right now we just have to guess.
ssh (via putty) says "connection refused"
by theoldwizard1
Sat Apr 30, 2016 10:32 am
Forum: Beginners
Topic: Light Display Manager does not start (using HDTV display)
Replies: 8
Views: 1790

Re: Light Display Manager does not start (using HDTV display

drgeoff wrote:Using the config to expand the file system is ALWAYS the FIRST thing that should be done on FIRST boot of Raspbian.
sudo raspi-config starts but task 1 (expannd file system fails) FAILS
by theoldwizard1
Fri Apr 29, 2016 12:34 am
Forum: Beginners
Topic: Light Display Manager does not start (using HDTV display)
Replies: 8
Views: 1790

Re: Light Display Manager does not start (using HDTV display

topguy wrote:How good power-supply are you using ?
Brand new, Adafruit, 2.4A
topguy wrote:SD-card ? is that OK ?
Brand new, SanDisk Extreme Pro 16GB
topguy wrote:It should work better with a TV than with a monitor, but you havent mentioned make/model of the TV.
Samsung LN40B540FXZA
by theoldwizard1
Thu Apr 28, 2016 8:39 pm
Forum: Beginners
Topic: Light Display Manager does not start (using HDTV display)
Replies: 8
Views: 1790

Light Display Manager does not start (using HDTV display)

Raspbian Jessie, Raspberry Pi 3. I am using my HDTV (full 1080p capable) as my display until I can get a HDMI to DVI cable for my desktop device. I get a error message that LSB failed to start. I rebooted and I don't think I got that error message, but now Light Display Manager has failed to start s...

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