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by RattusRattus
Sun Mar 17, 2019 11:16 pm
Forum: General programming discussion
Topic: Mixing C and assembly?
Replies: 18
Views: 2539

Re: Mixing C and assembly?

links inside the ARM document apear to be dead

you will certainly need the Procedure call standard
http://infocenter.arm.com/help/topic/co ... _aapcs.pdf

/Rattus
by RattusRattus
Sun Mar 17, 2019 11:05 pm
Forum: Python
Topic: spi and max7219 issues with custom board
Replies: 2
Views: 434

Re: spi and max7219 issues with custom board

OK before we start to look at software issues lets look at the physical hardware first you have posted partial schematics... that is ok but you are not showing enough connection detail I can see that you are running the data and clock signals through a bunch of Schmitt inverters to clean up the sign...
by RattusRattus
Sun Mar 17, 2019 10:18 pm
Forum: General discussion
Topic: Let's share lifespan optimizations for microSD cards.
Replies: 3
Views: 523

Re: Let's share lifespan optimizations for microSD cards.

You are dealing with Logical blocks only

The wear levelling happens on the physical FLASH

The file system shouldn't matter (That said I am aware that some controllers do performance optimise for FAT32, by careful cache management)


/Andy
by RattusRattus
Sun Mar 17, 2019 9:48 pm
Forum: General programming discussion
Topic: Mixing C and assembly?
Replies: 18
Views: 2539

Re: Mixing C and assembly?

Hi ab1jx So there are absolute rules for mixing assembly and C. Just traps to catch you out.... The calling convention is very much target specific. At the moment that would be "ARMv6 + Hard Floating point" if you want to work on all Pis. of cause if you just want to go 64 bit for a Pi 3 then you co...
by RattusRattus
Mon Dec 03, 2018 3:27 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI + GPI interface
Replies: 4
Views: 2527

Re: SPI + GPI interface

So linux has a GPIO driver that you can play around with from the command line. see /sys/class/gpio I would use that to initially play with the GPIO lines (not the SPI lines) that you conect to the DAC. simply read and write files (direction, value etc) for the appropriate pin Likewise the SPI drive...
by RattusRattus
Wed Nov 21, 2018 3:26 pm
Forum: Advanced users
Topic: pigpio--scheduling a future interrupt
Replies: 2
Views: 1455

Re: pigpio--scheduling a future interrupt

I may have compleatly missunderstood your question.

I am interpreting it as this:
"Is there a way to get an interrupt to happen at a given time without using GPIO lines?"

*IF* that is what you are asking then take a look at "signal ( SIGALRM, <handler>);" in <signal.h>

/Andy
by RattusRattus
Wed Nov 21, 2018 11:56 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI + GPI interface
Replies: 4
Views: 2527

Re: SPI + GPI interface

Please expand your question. I don't understand what you are asking so I can only offer some general advice for now: * The ADS868x is able to interface with the Pi as you have already suggested using SPI and a handful of GPIO lines. * It is 3V3 logic so you will not need any level shift. * The SPI b...
by RattusRattus
Fri Nov 09, 2018 12:47 pm
Forum: Automation, sensing and robotics
Topic: Read Temperature from Omron K3MA
Replies: 7
Views: 1705

Re: Read Temperature from Omron K3MA

if you turn the unit round you will find a nice clear display. When the K3MA is turned on and connected correctly use Mk-I human eyeball to look at the display.... Seriously though... Your question boils down to this: "I have <device> and I want to connect it to my RPi. " The question that you need ...
by RattusRattus
Fri Nov 09, 2018 12:09 pm
Forum: General discussion
Topic: Raspberry pi 30A relay
Replies: 15
Views: 1952

Re: Raspberry pi 30A relay

CAUTION I HAVE NOT SEEN THE SCHEMATICS - I AM OFFERING AN OPINION BASED ON YOUR POST AND LOOKING AT THE EBAY ITEM ONLY This looks like there is a power supply to drive the 'solid state' (?) relays sate between the two. As such it looks like you need to give the system mains (either 110 or 240VAV) on...
by RattusRattus
Mon Oct 08, 2018 1:41 pm
Forum: Graphics, sound and multimedia
Topic: Recording sound (and video at the same time) with the Pi 3B+
Replies: 12
Views: 2573

Re: Recording sound (and video at the same time) with the Pi 3B+

indeed The pi would make (and does make) good electonics of an IP camera Debian doesn't use Pis for this because we want nice big lenses and sensors that we can run 24x7 with motor zooms etc etc. hence using semi pro camera gear we then use SDI to take a RAW feed from the camer into the PC we mix on...
by RattusRattus
Mon Oct 08, 2018 11:42 am
Forum: Beginners
Topic: Clearing gpio event detect flag
Replies: 1
Views: 331

Re: Clearing gpio event detect flag

Hi Alvin, I think I have understood your question correctly. You have 4 GPIO inputs and are using them to decode upto 15 switches. So you have already encoded the switches into binary. you get a state change signal which calls your routine. you read the state of all 4 lines, then clear the flag It i...
by RattusRattus
Mon Oct 08, 2018 11:19 am
Forum: General discussion
Topic: Uploads via other GPIO pins
Replies: 1
Views: 251

Re: Uploads via other GPIO pins

I tend to use AVRDUDE
You can bit bang most ardueno's (without bootloader) over GPIO from your Pi. You will need 4 GPIO lines for SPI programming (to connect to /RST SCLK MOSI and MISO on the AVR). You can alocate any free GPIO lines from the Pi for this task

/Andy
by RattusRattus
Mon Oct 08, 2018 11:08 am
Forum: Graphics, sound and multimedia
Topic: Recording sound (and video at the same time) with the Pi 3B+
Replies: 12
Views: 2573

Re: Recording sound (and video at the same time) with the Pi 3B+

I was going for capturing video thanks to a modified Pi camera (ArduCam). If we need several Pis to do the job, that's ok too. one Pi, one PiCamera will be fine. But you will still have an issue with getting sound onto the system as I can't see any mention of a mic input on the ArduCam (but then I ...
by RattusRattus
Thu Oct 04, 2018 4:39 pm
Forum: Advanced users
Topic: Trying to read camera inputs from two Raspberry Pi 2B's through a network
Replies: 1
Views: 399

Re: Trying to read camera inputs from two Raspberry Pi 2B's through a network

If by network you are meaning TCP/IP over Ethernet then sorry it's not going to happen easily. There will be just too much jitter for your depth perception algorythem to cope. To overcomethis you will need to synchonise the timing for both cameras AND have that timing available as part of your proce...
by RattusRattus
Thu Oct 04, 2018 4:29 pm
Forum: General discussion
Topic: Wire setting for my heat sensor with rpi3 b plus
Replies: 4
Views: 535

Re: Wire setting for my heat sensor with rpi3 b plus

Differant modules will have differant pin-outs. The best you can do is use a multi-meter to 'buzz-out' the pins. The DHT11 data sheet tells you the pin numbering for the sensor itself: Pin Description 1, the VDD power supply 3.5~5.5V DC 2 DATA serial data, a single bus 3, NC, empty pin 4, GND ground...
by RattusRattus
Thu Oct 04, 2018 4:18 pm
Forum: Graphics, sound and multimedia
Topic: Recording sound (and video at the same time) with the Pi 3B+
Replies: 12
Views: 2573

Re: Recording sound (and video at the same time) with the Pi 3B+

Hi there Gounthar You have suggested that you want to record sound and video from conferances Firstly if you are wanting to record video then sound will not be a problem. Video needs a lot more bandwidth than sound. If you are intending on capturing video then the resolution, and bitrate of your vid...
by RattusRattus
Wed Oct 03, 2018 9:21 pm
Forum: HATs and other add-ons
Topic: HAT design - Vendor info atom
Replies: 5
Views: 2024

Re: HAT design - Vendor info atom

Hi again I guess I see the use case differantly to you <shrug> I agree having the device tree blob stored on the HAT is fundamental for kernel driver use, it is the rest I am struggling with. WRT the EEPROM content I get and uncderstand the headder and atom3, I still struggle to 'see' the obvious fo...
by RattusRattus
Wed Oct 03, 2018 7:25 pm
Forum: HATs and other add-ons
Topic: HAT design - Vendor info atom
Replies: 5
Views: 2024

Re: HAT design - Vendor info atom

Thanks for the response I am beginning to think that the whole HAT concept is unfortunately flawed. Given that the identification of a HAT is not possible by looking at structured content of the EEPROM why even bother with the EEPROM in the first place? I mean if there is no control over PID then I ...
by RattusRattus
Sat Sep 29, 2018 12:45 pm
Forum: HATs and other add-ons
Topic: PoEHAT - Ethernet cablie current capabilities
Replies: 2
Views: 2361

Re: PoEHAT - Ethernet cablie current capabilities

There are specifications for ethernet cables, CAT5, CAT5e, CAT6 etc. Amongst the specified parameters the standards specify or imply: - The maximum resistance per meter (i.e. Ohms/meter) - a minimum value for maximum current load - a minimum value for maximum working voltage PoE is able transmit rel...
by RattusRattus
Sat Sep 29, 2018 12:10 pm
Forum: HATs and other add-ons
Topic: HAT design - Vendor info atom
Replies: 5
Views: 2024

HAT design - Vendor info atom

HI there, So I am in the process of creating my first HAT, for a product that will provide multiple hardware accelerated 1-Wire interfaces to overcome the limitations of the existing 1-Wire drivers and their accocated hardware shortcommings. The documentation for HATs tells me that I need an CAT24C3...

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