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by chaosjug
Tue Mar 13, 2018 8:13 pm
Forum: C/C++
Topic: The most efficient way to transfer SPI data
Replies: 9
Views: 4252

Re: The most efficient way to transfer SPI data

The ADC124S101 has a maximum clock speed of 16Mhz, so if you want 1MSample/s the SPI bus needs to continuously transfer data. If it is possible at all, you need to use DMA. The idea is that the SPI runs independent of the CPU reading and writing to a memory buffer via DMA (note: you need SPI0 for th...
by chaosjug
Tue Jan 30, 2018 7:27 pm
Forum: C/C++
Topic: Software vs Hardware SPI
Replies: 2
Views: 2385

Re: Software vs Hardware SPI

This really depends on your application. How fast your SPI device is and how much data you want to transfer. There are two things to consider: Hardware SPI can use higher frequencies (if your SPI device is fast enough) and at least SPI0 can use DMA so you can transfer large amounts of data without t...
by chaosjug
Tue Dec 12, 2017 6:20 pm
Forum: General discussion
Topic: Raspberry Pi Zero bluetooth connection to android phone.
Replies: 6
Views: 3382

Re: Raspberry Pi Zero bluetooth connection to android phone.

Hi,

you can either make a wifi hotspot or tether with bluetooth. Both should work. I haven't tried a wifi hotspot myself but I would expect this to be faster than the bluetooth version. If your interested in bluetooth tethering I can try writing down what I did to get it working.
by chaosjug
Sun Dec 03, 2017 6:33 pm
Forum: C/C++
Topic: Unknown symbol spi_register_board_info
Replies: 3
Views: 901

Re: Unknown symbol spi_register_board_info

Hi, if you are not in the boardfile, spi_register_board_info() probably won't work. spi_new_device() is the way to go. What didn't work when you tried it? Usually it helps most, when you look at the Documentation in the kernel source code, e.g. https://www.kernel.org/doc/Documentation/spi/spi-summar...
by chaosjug
Thu Nov 30, 2017 8:06 pm
Forum: C/C++
Topic: Unknown symbol spi_register_board_info
Replies: 3
Views: 901

Re: Unknown symbol spi_register_board_info

Hi,

without a working example it is hard to know what you are trying to do.
The code you posted usually belongs into the boardfile but that approach isn't used for the raspberry pi anymore. Instead the information should go into the devicetree.

Regards,
chaosjug
by chaosjug
Mon Oct 23, 2017 7:45 pm
Forum: C/C++
Topic: ISR preemption of wiringPi ISR
Replies: 3
Views: 1454

Re: ISR preemption of wiringPi ISR

Linux is no realtime operating system, so there is no guarantee how long it may take until e.g. an ISR is called. Even if you write a kernel driver and reduce the load on the system by uninstalling not needed services, it can still happen. Depending on your requirements there are some possible solut...
by chaosjug
Sat Jan 30, 2016 3:13 pm
Forum: Device Tree
Topic: dtoverlay_merge_params failed - err -3 [SOLVED]
Replies: 4
Views: 1415

Re: dtoverlay_merge_params failed - err -3 [SOLVED]

Updating the firmware with rpi-update did indeed fix the problem.
So it seems I was indeed hit by the same bug:
https://github.com/raspberrypi/firmware/issues/527
by chaosjug
Wed Jan 27, 2016 7:33 pm
Forum: Device Tree
Topic: device tree overlays and U-Boot
Replies: 32
Views: 13246

Re: device tree overlays and U-Boot

If you just want to enable I2C RTC you could also just write a small dts-file and compile it: #include "bcm2708-rpi-b-plus.dts" &i2c1 { status = "okay"; pcf8563: [email protected] { compatible = "nxp,pcf8563"; reg = <0x51>; status = "okay"; }; }; You'll obviously have to pick the correct RTC part from i2c-...
by chaosjug
Wed Jan 27, 2016 7:18 pm
Forum: Device Tree
Topic: dtoverlay_merge_params failed - err -3 [SOLVED]
Replies: 4
Views: 1415

Re: dtoverlay_merge_params failed - err -3 [SOLVED]

That was actually someone else. I can't take the credit for that :-)
But I've seen the bug report and will check if that fixes it for me too.
Just didn't get around doing the update and test it. I'll report back with the results.
by chaosjug
Wed Jan 13, 2016 9:13 pm
Forum: Device Tree
Topic: dtoverlay_merge_params failed - err -3 [SOLVED]
Replies: 4
Views: 1415

Re: dtoverlay_merge_params failed - err -3

I just managed to boot the raspi with this device tree using u-boot (http://elinux.org/RPi_U-Boot) so the device tree itself seems to be ok.
by chaosjug
Sun Jan 10, 2016 8:57 pm
Forum: Device Tree
Topic: dtoverlay_merge_params failed - err -3 [SOLVED]
Replies: 4
Views: 1415

dtoverlay_merge_params failed - err -3 [SOLVED]

Hi! I have problems with a custom device tree: #include <dt-bindings/input/input.h> #include <dt-bindings/clock/bcm2835-aux.h> #include <dt-bindings/gpio/gpio.h> #include "bcm2708-rpi-b-plus.dts" &soc { aux: [email protected] { compatible = "brcm,bcm2835-aux"; #clock-cells = <1>; reg = <0x7e215000 0x8>...
by chaosjug
Sun Mar 15, 2015 7:34 pm
Forum: Astro Pi
Topic: Flight Hardware Tech Specs
Replies: 9
Views: 3772

Re: Flight Hardware Tech Specs

Is it true, that the interrupt pins of the LSM9DS1 are not connected to any GPIO?
by chaosjug
Tue Dec 30, 2014 10:52 am
Forum: Automation, sensing and robotics
Topic: 433MHz receivers?
Replies: 13
Views: 4007

Re: 433MHz receivers?

The problem with the raspi is, that you have to measure the time of the pulse or pause accurately enough to decide if it represents a 1 or a 0. I tried using GPIO interrupts but linux is not a real time system so the time between rising or falling edge at the pin and when my interrupt service routi...
by chaosjug
Mon Dec 29, 2014 5:56 pm
Forum: Automation, sensing and robotics
Topic: 433MHz receivers?
Replies: 13
Views: 4007

Re: 433MHz receivers?

I've been doing something similar and it works more or less, but it is a bit tricky. There are several problems to be solved: 1. You have to find out how to decode the signals you want to receive. I've done this using a DVB dongle and this software https://github.com/merbanan/rtl_433 The advantage i...
by chaosjug
Sun Dec 21, 2014 9:38 pm
Forum: Automation, sensing and robotics
Topic: BerryIMU Kickstarter
Replies: 3
Views: 1979

Re: BerryIMU Kickstarter

This sounds very promising especially with pressure and temperature sensor.
But nowhere on the pictures I can see a pin for the data ready interrupts from the sensors.
This is especially important for the gyro/accel to make sure you get all values.
Are there any plans to add those?
by chaosjug
Sun Dec 21, 2014 9:13 pm
Forum: Automation, sensing and robotics
Topic: Guide to interfacing a Gyro and Accelerometer with a Raspber
Replies: 1
Views: 1599

Re: Guide to interfacing a Gyro and Accelerometer with a Ras

Have you thought about using the kernel modules? At least for the LSM303DLHC there is an IIO driver (st_accel_i2c / st_magn_i2c). Not sure about the L3GD20H. There is a driver which supports the L3GD20 but I didn't check if there is any difference between the two.
by chaosjug
Wed Dec 17, 2014 1:39 pm
Forum: C/C++
Topic: kernel irq allocation problem
Replies: 0
Views: 471

kernel irq allocation problem

Hi, I'm not sure if this is the best place to ask kernel related question, but as it is very raspberrypi specific I give it a try: I'm using a gyro/accel-sensor which is connected via I2C and has a kernel driver. The driver is working but I had problems when I started using an external trigger. The ...
by chaosjug
Wed Nov 05, 2014 8:33 pm
Forum: Media centres
Topic: Raspberry Pi + MPD as UPnP client
Replies: 9
Views: 12174

Re: Raspberry Pi + MPD as UPnP client

I compiled the current mpd (0.19.2) with upnp support. When I connect with a client, I can see my upnp-servers under files, but no artist/songs etc. When I select one of the servers I see this in the logfile: upnp: UpnpSendAction() failed: UPNP_E_INVALID_URL In the server log I can see no connection...

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