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by msperl
Sun Oct 02, 2016 10:08 am
Forum: Raspbian
Topic: Introducing PIXEL desktop: new Raspbian release
Replies: 193
Views: 49413

Re: Introducing PIXEL desktop: new Raspbian release

If you are using the experimental graphic driver, turn it off , they are incompatible at the moment. I have justed used the default raspbian image and nothing more and then updated it as per documentation! Note: it turns out that chromium is incompatible with libgl1-mesa-swx11, which - for some rea...
by msperl
Sat Oct 01, 2016 9:33 am
Forum: Raspbian
Topic: Introducing PIXEL desktop: new Raspbian release
Replies: 193
Views: 49413

Re: Introducing PIXEL desktop: new Raspbian release

If you are using the experimental graphic driver, turn it off , they are incompatible at the moment. I have justed used the default raspbian image and nothing more and then updated it as per documentation! Only changes to boot had to do with HDMI: pi@rpi3c:~ $ grep -v "#" /boot/config.txt | sort | ...
by msperl
Fri Sep 30, 2016 8:25 am
Forum: Raspbian
Topic: Introducing PIXEL desktop: new Raspbian release
Replies: 193
Views: 49413

Re: Introducing PIXEL desktop: new Raspbian release

After upgrading to Pixel on my rpi3 (with all the steps as per the announcement - dist_upgrade and install chromium-mods) starting chromium results in the window staying blank and it does not redraw and chromium consumes 40% CPU. If I start chromium from the command line I get the following messages...
by msperl
Thu May 05, 2016 3:44 pm
Forum: Camera board
Topic: picam producing strong orange tint
Replies: 2
Views: 660

Re: picam producing strong orange tint

With the new camera V2.1 it looks as if the red/orange tint is gone.

(But there may be some awb issues during cloudy/hazy conditions - more observations are needed -> different thread)
by msperl
Thu Mar 17, 2016 12:35 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 804
Views: 266060

Re: CAN controller

SPI-DMA does not help and would in this case actually be counter-productive. a) right now the DMA-engine will produce 1 interrupt per dma channel used (and SPI requires 2 channels b) interrupt driven SPI works very well for transfers up to 64 bytes (fifo size) and in our case of < 16 bytes will trig...
by msperl
Sun Mar 06, 2016 8:02 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Maximum SPI Devices
Replies: 15
Views: 2719

Re: Maximum SPI Devices

Assuming you use the Linux kernel:
If you add

Code: Select all

gpio-cs = <&gpio 8>, <&gpio 7>,<&gpio 22>;
to the devicetree, then gpios 8, 7 and 22 will be used for CS 0,1 and 2. Add more until satisfied...
by msperl
Mon Sep 28, 2015 4:53 pm
Forum: C/C++
Topic: SPI DMA Driver for Raspberry Pi 2
Replies: 12
Views: 3360

Re: SPI DMA Driver for Raspberry Pi 2

Example code: struct mydevice_priv { struct spi_device *spi; struct spi_message spi_msg; struct spi_transfer spi_xfer; char data_tx[500]; char data_rx[500]; }; static irqreturn_t mydevice_irq_handler(int irq, void *dev_id) { struct mydevice_priv *priv = dev_id; struct spi_device *spi = priv->spi; /*...
by msperl
Mon Sep 28, 2015 3:56 pm
Forum: C/C++
Topic: SPI DMA Driver for Raspberry Pi 2
Replies: 12
Views: 3360

Re: SPI DMA Driver for Raspberry Pi 2

From userspace just use SPIDEV, which shall use DMA transparently with any of the new foundation-provided kernels (e.g. 4.1 or higher) - this works for all versions of the rpi.
by msperl
Mon Sep 28, 2015 10:03 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: WS2812B and apa102 - spi driver
Replies: 1
Views: 796

WS2812B and apa102 - spi driver

Hi! I have created an initial version of a customizable framebuffer driver for WS2812B and APA102 (untested) RGBLed strings connected to SPI via a 74HCT125 acting as a level translator. I am currently cleaning up the code and trying to get it upstreamed and into the official foundation kernels. If a...
by msperl
Sun Sep 13, 2015 7:02 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Image SD card with SPI
Replies: 2
Views: 388

Re: Image SD card with SPI

Works with an old kernel, but unfortunately spi-mmc has an issue in the latest kernels, that make it not work without a patch...
by msperl
Fri Jul 10, 2015 1:28 am
Forum: Device Tree
Topic: newer version of dtc that allows for 4.2 style #include
Replies: 3
Views: 914

Re: newer version of dtc that allows for 4.2 style #include

That is all right on its own, but if you want to compile a dt-overlay outside of the kernel, then you will start to have an issue eventually. The foundation still can use their own dts that does not make use of that, but it may become an issue in the future... So maybe you should put a warning somew...
by msperl
Thu Jul 09, 2015 4:06 am
Forum: Device Tree
Topic: newer version of dtc that allows for 4.2 style #include
Replies: 3
Views: 914

newer version of dtc that allows for 4.2 style #include

Hi! Seems as if the upstream 4.2-rc kernels start to use "#include" instead of "/include/" in their device tree definitions. See: https://github.com/torvalds/linux/blob/master/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts These are neither supported in dtc 1.3 nor 1.4 - kernel 4.2 seems to ship with 1.4....
by msperl
Tue Jun 23, 2015 10:54 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI driver latency and a possible solution
Replies: 242
Views: 85055

Re: SPI driver latency and a possible solution

Note that the dma-patch for the driver is now a candidate for 4.2 - as soon as it gets included in the branch of 4.2 I will ask the foundation to cherrry-pick the patch and move it into their 4.0 branch...
by msperl
Mon Jun 22, 2015 3:34 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 804
Views: 266060

Re: CAN controller

If you are asking: can I run multiple can boards (mcp251x or otherwise)? Then the answer is yes: you can easily do that - right now I run 2 mcp2515 and it works fine (with the correct device-tree). You can even add some kernel based CAN-bridging between the two interfaces by using the cangw tool to ...
by msperl
Thu Jun 18, 2015 1:11 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI driver latency and a possible solution
Replies: 242
Views: 85055

Re: SPI driver latency and a possible solution

I patched my local kernel branch to have a cs_change_usecs variable in the spi_transfer structure so the toggle time could be set to 1us (or more) instead of the fixed 10us with the default cs_change_usecs value of 0. If you want to have that then please consider up-streaming this to the linux kern...
by msperl
Tue May 19, 2015 9:10 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 804
Views: 266060

Re: CAN controller

If you go that route then you might just as well go all the way to use USB directly and leave SPI behind.
Then the device is not focused on one specific HW (=RPI) and can get just as easily get reused with other boards as well...
slcan is then probably the best choice.
by msperl
Sat May 16, 2015 3:54 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI has more speeds
Replies: 15
Views: 30021

Re: SPI has more speeds

It is fairly simple to achieve that with a device-tree with a 3.18 foundation kernel (or self-built).

Look at the mcp2515-can0-overlay as an example of how it can get done:
https://github.com/raspberrypi/linux/bl ... verlay.dts
by msperl
Fri May 15, 2015 1:09 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 804
Views: 266060

Re: CAN controller

if you look at the exact format for slcan encapsulation:
<type> <id> <dlc> <data>*

so you get: 1(type)+4*2(id)+1(dlc)+2*8(data)+1("\r")
so 27 bytes.
by msperl
Fri May 15, 2015 12:52 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 804
Views: 266060

Re: CAN controller

Seen slcan - IMO the problem is that: a) you loose the serial port on the pi (but you could run that over USB) b) you are limited to low transfer speeds of the UART on the RPI (4MBit max if I remember - and that was not always stable) c) you are limited by the text protocol of slcan that essentially...
by msperl
Fri May 15, 2015 7:22 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 804
Views: 266060

Re: CAN controller

@skpang: Well - maybe we should move this to a different thread? But I got some "basic" protocol ideas that would make things "easy" and a very efficient streaming protocol: The principles are: * we only run one spi message to handle the transfers in and out * almost everything is a CAN message when...
by msperl
Thu May 14, 2015 10:55 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: External SDCARD with FatFs module
Replies: 12
Views: 6548

Re: External SDCARD with FatFs module

the corresponding device tree looks like this: sd1: sd@1 { reg = <1>; status = "okay"; compatible = "spi,mmc_spi"; voltage-ranges = <3200 3500>; spi-max-frequency = <8000000>; }; so all you need to do is write an overlay file... Note that there is ONE catch that I have experienced: make sure that mm...
by msperl
Thu May 14, 2015 10:49 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: External SDCARD with FatFs module
Replies: 12
Views: 6548

Re: External SDCARD with FatFs module

Note that there is an issue introduced somewhere in 3.13 that produces hickups detecting the sd card when loading mmc-spi. It was a simple patch similar to this: diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c index ae19d83..e21b8be 100644 --- a/drivers/mmc/host/mmc_spi.c +++ b/...
by msperl
Thu May 14, 2015 10:22 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 804
Views: 266060

Re: CAN controller

actually I recommend using the spi-bcm2835 driver now with the latest kernel provided by the foundation All you have to do is switch by adding: dtoverlay=spi-bcm2835-overlay to /boot/config.txt and then load spi-bcm2835 instead of spi-bcm2708. a future 4.0 (or later) kernel should give even better r...
by msperl
Thu May 14, 2015 10:19 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI has more speeds
Replies: 15
Views: 30021

Re: SPI has more speeds

note that this is is already in the spi-bcm2835 driver for 3.18.y kernels by the foundation. All you have to do is switch by adding: dtoverlay=spi-bcm2835-overlay to /boot/config.txt and then load spi-bcm2835 instead of spi-bcm2708. And then you get this plus some more optimizations/features out of ...
by msperl
Wed May 13, 2015 1:49 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 804
Views: 266060

Re: CAN controller

Well - maybe a STM32F103 is also a good candidate (slightly more expensive) It comes with 20Kb SRAM, so we could even keep the firmware (besides a boot-loader) in ram and upload it via the kernel firmware APIs from /lib/firmware/... This makes updating the firmware cheap... Got one of those boards o...

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