Go to advanced search

by dp11
Sat May 30, 2020 7:54 am
Forum: Off topic discussion
Topic: Raspberry Pi as a card concept
Replies: 51
Views: 2677

Re: Raspberry Pi as a card concept

Sorry people, but can we keep this thread on topic please.
by dp11
Fri May 29, 2020 4:19 pm
Forum: Compute Module
Topic: Compute Module 3+ and LAN9512
Replies: 4
Views: 109

Re: Compute Module 3+ and LAN9512

I understand why you can't share the rest of the information, but without full information I'm just randomly guessing , the snippet of circuits doesn't rule out a USB issue in my mind. Might be time to probe the USB signals will a differential probe and a high speed scope. Others have the LAN9512 wo...
by dp11
Fri May 29, 2020 4:00 am
Forum: Compute Module
Topic: Compute Module 3+ and LAN9512
Replies: 4
Views: 109

Re: Compute Module 3+ and LAN9512

How have you connected the USB up? Can you post your schematics and board layout?
by dp11
Tue May 26, 2020 8:24 am
Forum: Bare metal, Assembly language
Topic: Pi3 - VCHIQ - mailbox property returns 0xffff_ffff when setting base address
Replies: 9
Views: 346

Re: Pi3 - VCHIQ - mailbox property returns 0xffff_ffff when setting base address

I would say share everything. Otherwise we are flying blind too :)
by dp11
Mon May 25, 2020 10:07 pm
Forum: Bare metal, Assembly language
Topic: Pi3 - VCHIQ - mailbox property returns 0xffff_ffff when setting base address
Replies: 9
Views: 346

Re: Pi3 - VCHIQ - mailbox property returns 0xffff_ffff when setting base address

I'm no expert but is the data stuck in the ARM cache? ie have you flush it?
by dp11
Tue May 12, 2020 10:44 am
Forum: C/C++
Topic: New major release of GCC
Replies: 74
Views: 2558

Re: New major release of GCC

If you find a false positives from cppcheck you can submit it https://trac.cppcheck.net/

apt doesn't yet appear to have the latest version.
by dp11
Tue May 12, 2020 8:52 am
Forum: C/C++
Topic: New major release of GCC
Replies: 74
Views: 2558

Re: New major release of GCC

Also worth trying the link time optimisation feature -flto if you aren't already.

For static analysis I also use : http://cppcheck.sourceforge.net/
by dp11
Tue Apr 28, 2020 6:54 pm
Forum: C/C++
Topic: Failed to use ARM timer with FIQ on rpi zero (BCM2835)
Replies: 5
Views: 278

Re: Failed to use ARM timer with FIQ on rpi zero (BCM2835)

I'm more of a bare metal programmer. Is the stack actually available to the FIQ handler and in which memory domain? ie. if your task is swapped out doesn't it still exist and at what address? I suspect __set_fiq_regs has a lot of history. I don't know why it loads R14 for instance as entry into FIQ ...
by dp11
Tue Apr 28, 2020 2:18 pm
Forum: Advanced users
Topic: ADC, DAC, and noise
Replies: 9
Views: 434

Re: ADC, DAC, and noise

I think I have found the app note http://www.ti.com/lit/ml/slyc147/slyc147.pdf for anyone else interested. The capacitor selection is critical to keep the design stable.
by dp11
Tue Apr 28, 2020 9:44 am
Forum: C/C++
Topic: Failed to use ARM timer with FIQ on rpi zero (BCM2835)
Replies: 5
Views: 278

Re: Failed to use ARM timer with FIQ on rpi zero (BCM2835)

I'm not sure where set_fiq_regs is defined? what happens to the registers you don't define in the structure ? e.g. the stack
by dp11
Tue Apr 28, 2020 8:38 am
Forum: Advanced users
Topic: ADC, DAC, and noise
Replies: 9
Views: 434

Re: ADC, DAC, and noise

I feel very sorry for the OPA350 opamp driving a 10uF load
by dp11
Thu Apr 16, 2020 4:11 pm
Forum: Compute Module
Topic: CM3 with LAN9514 USB works only with oscilloscope probe
Replies: 5
Views: 293

Re: CM3 with LAN9514 USB works only with oscilloscope probe

It difficult to say without accurate measurements, if the impedance is causing an issue. A good tool for PCB design is http://saturnpcb.com/pcb_toolkit/ and give 113Ohms for your diff pair, with a Zo of 73 Ohms . For USB Zo should be 45Ohms. I agree you should try to understand all the issues before...
by dp11
Wed Apr 15, 2020 3:47 pm
Forum: Compute Module
Topic: CM3 with LAN9514 USB works only with oscilloscope probe
Replies: 5
Views: 293

Re: CM3 with LAN9514 USB works only with oscilloscope probe

You may already know this , but the ground plane under the differential pair should be solid with no splits for the entire length of the differential pair. Adding a scope to the signal effectively add a small amount of capacitance which will change the signal and if it is marginal may make things wo...
by dp11
Wed Apr 15, 2020 2:57 pm
Forum: Compute Module
Topic: CM3 with LAN9514 USB works only with oscilloscope probe
Replies: 5
Views: 293

Re: CM3 with LAN9514 USB works only with oscilloscope probe

I assume your USB differential pairs are routed at 90ohm differential signals ? Can you post your layout files ?
by dp11
Fri Sep 27, 2019 4:17 am
Forum: Troubleshooting
Topic: *ERROR* Resetting GPU when temperature under 37C
Replies: 12
Views: 840

Re: *ERROR* Resetting GPU when temperature under 37C

Are you overclocking?
by dp11
Sun Sep 08, 2019 6:22 pm
Forum: Troubleshooting
Topic: New Raspberry Pi 4 won't boot
Replies: 6
Views: 2084

Re: New Raspberry Pi 4 won't boot

Can you tell us exactly how you setup the SDCARD?
by dp11
Fri Aug 16, 2019 6:29 am
Forum: General discussion
Topic: Why moving to 64bit?
Replies: 273
Views: 32773

Re: Why moving to 64bit?

My understanding is that if the crypto instructions exist they also exist in 32bit world. See pdf near the end for instruction timings http://infocenter.arm.com/help/index.js ... index.html
by dp11
Tue Aug 13, 2019 6:42 pm
Forum: Troubleshooting
Topic: pi 4B not showing Video on HDMI0 if memory split set to 896MB
Replies: 23
Views: 3297

Re: pi 4B not showing Video on HDMI0 if memory split set to 896MB

Just because things don't work with Buster doesn't mean other bare metal OSes won't work.
by dp11
Thu Jul 25, 2019 6:36 pm
Forum: C/C++
Topic: PI4 and GPIO not working
Replies: 2
Views: 538

Re: PI4 and GPIO not working

Try 0xFE000000 as the base address.
by dp11
Fri Jul 19, 2019 6:04 pm
Forum: Bare metal, Assembly language
Topic: RPI2 ATAGS returns strange value
Replies: 2
Views: 1044

Re: RPI2 ATAGS returns strange value

Try removing the device tree files from the sdcard.
by dp11
Wed Jul 10, 2019 4:28 pm
Forum: General discussion
Topic: Pi4b J2 Run Global_En as power
Replies: 6
Views: 1614

Re: Pi4b J2 Run Global_En as power

These pins aren't suitable for running a fan.
by dp11
Tue Jul 09, 2019 9:58 pm
Forum: Compute Module
Topic: LAN9514
Replies: 28
Views: 7128

Re: LAN9514

sorry getting mixed up with something else .

The LAN9512 saves about 200mW over the LAN9514 with the loss of two USB ports.

If you can force Full Speed USB this will also reduce power dissipation.
by dp11
Tue Jul 09, 2019 6:20 pm
Forum: General discussion
Topic: 3v3 drops on Pi4 reboot
Replies: 5
Views: 727

Re: 3v3 drops on Pi4 reboot

If you need 3.3v to stay up then the best way is to create it from the 5v rail.
by dp11
Tue Jul 09, 2019 4:23 pm
Forum: Compute Module
Topic: LAN9514
Replies: 28
Views: 7128

Re: LAN9514

Do you need Gigabit ethernet? if not can you use the lan9512?
by dp11
Tue Jun 25, 2019 10:09 am
Forum: Beginners
Topic: RPI4 USB C Power Delivery negotiation
Replies: 22
Views: 14260

Re: RPI4 USB C Power Delivery negotiation

Any 15Watt or greater TypeC charger that meets the USB specification should be fine. If your charger has a socket it is important that a good quality USB cable is used.

Go to advanced search