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by bitbank
Tue Nov 21, 2017 3:39 pm
Forum: Troubleshooting
Topic: SPI rx buffer size.
Replies: 9
Views: 1236

Re: SPI rx buffer size.

It would help to debug your problem if you told us what SPI device you're reading from and shared the relevant source code.
by bitbank
Mon Nov 20, 2017 1:34 pm
Forum: Troubleshooting
Topic: SPI rx buffer size.
Replies: 9
Views: 1236

Re: SPI rx buffer size.

The default max buffer size for SPI is 4096 bytes. Show us your code and we'll have a better chance of finding the problem.
by bitbank
Wed Nov 15, 2017 10:05 pm
Forum: General discussion
Topic: What do you use your RPi(s) for?
Replies: 7
Views: 911

What do you use your RPi(s) for?

Please share what you do with your RPi board(s). It's interesting to understand how the community is divided into different use cases.
by bitbank
Mon Nov 13, 2017 1:48 am
Forum: Automation, sensing and robotics
Topic: Sense Hat Unchained - new C library on github
Replies: 2
Views: 1077

Re: Sense Hat Unchained - new C library on github

Thanks for the clarification - I removed references to 'proprietary' from the documentation.
by bitbank
Sun Nov 12, 2017 11:53 pm
Forum: Automation, sensing and robotics
Topic: Sense Hat Unchained - new C library on github
Replies: 2
Views: 1077

Sense Hat Unchained - new C library on github

I just released a new C library which communicates with the LEDs and sensors on the Sense Hat without the need for kernel drivers or RPI hardware. The "unchained" part refers to the ability to use the Sense Hat on any system with an I2C bus. In my case, I tested this software on other ARM SBCs. http...
by bitbank
Tue Nov 07, 2017 4:32 pm
Forum: Automation, sensing and robotics
Topic: C Library for VL53L0X time of flight distance sensor
Replies: 2
Views: 3986

C Library for VL53L0X time of flight distance sensor

The VL53L0X is a great sensor for measuring accurate distances between 4 and 100cm. The problem is that ST Micro designed the I2C interface specifically to hide the details of how to use the chip. Their documentation doesn't actually include any info about how to communicate with it over I2C. They p...
by bitbank
Sun Nov 05, 2017 2:55 pm
Forum: Automation, sensing and robotics
Topic: C library for CCS811 air quality sensor
Replies: 0
Views: 651

C library for CCS811 air quality sensor

I just released my C library for communicating with the CCS811 air quality sensor: https://github.com/bitbank2/CCS811 A few things to note: You should let it run for 48 hours for its initial burn-in period. It also requires 20 minutes to warm up each time it's used. I found it to be very sensitive t...
by bitbank
Sun Nov 05, 2017 2:50 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CCS811 Driver
Replies: 2
Views: 1427

Re: CCS811 Driver

I just released such a library here: https://github.com/bitbank2/CCS811 It has a simple C interface and will do what you want. I found that there are lots of read errors on Raspberry Pi boards. Others have commented that this has something to do with "clock stretching". I also connected it to my Ora...
by bitbank
Tue Oct 31, 2017 8:01 pm
Forum: General discussion
Topic: Using C to Control GPIO
Replies: 19
Views: 16136

Re: Using C to Control GPIO

Hi I have a Process Control Program, written in C, which I wish to use directly through the GPIO part of a Raspberry Pi #. I am currently running it on a 64 Bit Linux system. I wish to port it to the PI3 and as such require C code access to turn various items on and/or off. Does anyone have any 'sn...
by bitbank
Thu Oct 05, 2017 8:49 pm
Forum: C/C++
Topic: error problem transmitting spi data ..ioctl : invalid argument
Replies: 3
Views: 1917

Re: error problem transmitting spi data ..ioctl : invalid argument

Are you zeroing the SPI data structure? One of the fields which was unused is now used and you will get errors if it isn't zeroed. This change was made in the last year or so. I am zeroing the data structure. I'm also seeing lower throughput from the latest Allwinner (4.1x Linux kernel) drivers. On...
by bitbank
Thu Oct 05, 2017 7:41 pm
Forum: C/C++
Topic: error problem transmitting spi data ..ioctl : invalid argument
Replies: 3
Views: 1917

Re: error problem transmitting spi data ..ioctl : invalid argument

I've seen this error as well on other ARM boards. The data appears to transmit anyway. It looks more like a debugging log printed by the system. I don't see this issue on 3.x kernels, but I do see it on 4.x kernels. Do you have any more info about it?
by bitbank
Thu Oct 05, 2017 1:39 pm
Forum: General discussion
Topic: RPI Forum (server) still can't do keyword search
Replies: 2
Views: 428

RPI Forum (server) still can't do keyword search

Ever since the change to the newer forum software, keyword search has been broken. It's hit or miss, but mostly miss. If I search for a keyword, there is a delay followed by "our site is experiencing heavy traffic...". Navigating the forum tree or looking at my/new/unanswered posts works fine. Anyon...
by bitbank
Sun Oct 01, 2017 4:02 pm
Forum: Bare metal, Assembly language
Topic: Bare-metal SPI Display using GPU
Replies: 8
Views: 3545

Re: Bare-metal SPI Display using GPU

The fbtft and fbcp programs are generalized to work with any program which outputs to a framebuffer and translate that into a reasonable way to talk to an SPI connected LCD. The performance hit is because fbcp constantly copies the entire framebuffer to the virtual framebuffer created by fbtft (even...
by bitbank
Fri Sep 29, 2017 2:41 pm
Forum: Python
Topic: Getting current GPS time
Replies: 1
Views: 639

Re: Getting current GPS time

It sounds like you're not going to be able to get what you want from your setup. Linux is not a real time operating system, so system calls can take a variable amount of time and your program can get interrupted at any moment. When receiving the time value from the GPS receiver, there is an inherent...
by bitbank
Wed Sep 27, 2017 9:32 pm
Forum: Beginners
Topic: Connecting a 2.4" ILI9341 Display
Replies: 2
Views: 1047

Re: Connecting a 2.4" ILI9341 Display

The display you've got appears to not expose an SPI interface for the ili9341. It's got SPI for the SDCard and touch controller, but the display is a 16-bit parallel (8080) interface. It can be controlled by a Raspberry Pi, but it will take a lot of GPIO lines (21) to make it work. What some control...
by bitbank
Sun Sep 17, 2017 10:29 pm
Forum: Troubleshooting
Topic: SSD1306 problems on PI Zero
Replies: 7
Views: 1967

Re: SSD1306 problems on PI Zero

i am looking for answers too. its really put a damper on my enthusiasm to make and deploy raspberry solutions sadly... ive tried at least 10 different installs, adafruits, rmhull, alien-DNA-buttprobes everything.... i hate when people change code bases without keeping the old stuff available. :evil...
by bitbank
Fri Sep 15, 2017 5:52 pm
Forum: Off topic discussion
Topic: FYI - new RPI0W competitor appears
Replies: 3
Views: 1305

FYI - new RPI0W competitor appears

This is not an endorsement, just a heads-up that a new RPi0W competitor has been released by FriendlyElec. This one is called a NanoPi Duo and is a tiny Allwinner H2+ (Quad core Cortex-A7) board: http://linuxgizmos.com/tiny-open-spec-sbc-plugs-into-carrier-or-breadboards/ Retail price is $8 for 256M...
by bitbank
Wed Aug 30, 2017 1:43 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: KeDei 3.5 inch 480x320 TFT lcd from ali
Replies: 235
Views: 193552

Re: KeDei 3.5 inch 480x320 TFT lcd from ali

It looks like they switched LCD controllers on that model display. It doesn't need any GPIO lines for D/C nor RESET. It just has the 2 SPI chip selects for the touch controller and LCD controller. My SPI LCD code is designed for LCD controllers which require an external line to switch between D (dat...
by bitbank
Tue Aug 29, 2017 10:11 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: KeDei 3.5 inch 480x320 TFT lcd from ali
Replies: 235
Views: 193552

Re: KeDei 3.5 inch 480x320 TFT lcd from ali

just_zhenya wrote:
Tue Aug 29, 2017 8:54 pm
Nice try but it doesn't work for me.
My module doesn't even have D/C pin!
Please post a picture of the labeled connector of the LCD board.
by bitbank
Mon Aug 28, 2017 3:01 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: KeDei 3.5 inch 480x320 TFT lcd from ali
Replies: 235
Views: 193552

Re: KeDei 3.5 inch 480x320 TFT lcd from ali

If this display behaves like the KeiDei 3.5" SPI display that I have, (HX8357 controller), then you can also try using my C code to talk directly to it. I wrote a library to send the data as efficiently as possible to the LCD (sending as many bytes as possible in each write). You can compile it to u...
by bitbank
Fri Aug 25, 2017 10:18 pm
Forum: General discussion
Topic: Interesting to see what RPF has been up against
Replies: 14
Views: 2572

Interesting to see what RPF has been up against

I just found this article and it's quite an eye opener: https://blog.adafruit.com/2017/08/21/orange-pi-today-on-maker-business-adafruit-adafruitdaily-makerbusiness-orangepixunlong/ Essentially, the owner of Orange Pi (a Raspberry Pi competitor) admits that he sells all of his boards for bill-of-mate...
by bitbank
Fri Aug 25, 2017 7:40 pm
Forum: General programming discussion
Topic: Which language Python or Java or C++
Replies: 18
Views: 5536

Re: Which language Python or Java or C++

It wasn't clear from your original post what you were planning to do. Yes, you should be able to read 1 input at a time for a sequence of samples. If you do this in a round robin fashion and visit each of the inputs after so many samples captured, then it should be possible to do what you intend. I ...
by bitbank
Fri Aug 25, 2017 5:48 pm
Forum: General programming discussion
Topic: Which language Python or Java or C++
Replies: 18
Views: 5536

Re: Which language Python or Java or C++

Hi Jinu, It sounds like Java or C++ might be able to keep up (probably not Python), but the bigger impediment is the I2C bus. The standard I2C bus runs at 400Khz. It may be possible to run it faster, but you can safely assume that it's unlikely. I doubt that the ADC expander has efficient logic to r...
by bitbank
Fri Aug 25, 2017 2:59 pm
Forum: General discussion
Topic: 64bit vs 32bit benchmark. Eben was right
Replies: 65
Views: 20653

Re: 64bit vs 32bit benchmark. Eben was right

I had been holding on to some assumptions about this subject that were just rendered incorrect. I just did some testing and the 32 versus 64-bit argument is not cut and dried even for simple code execution. You're welcome to repeat my results by using my gcc_perf project: https://github.com/bitbank2...
by bitbank
Thu Aug 24, 2017 5:47 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: max SPI speed on PiZero
Replies: 3
Views: 3720

Re: max SPI speed on PiZero

Hello, I currently have a SPI display attached via a custom-made board to my PiZero GPIO Header. Everything works as expected. I am able to play a video or image sequences on my display at 5FPS. Now I'd like to achieve 10 or 12 fps. I seem to have found that the maixmum SPI speed I have is around 5...

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