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by Arjan
Wed Oct 17, 2012 12:59 pm
Forum: C/C++
Topic: UDP listener different behavior
Replies: 2
Views: 1424

Re: UDP listener different behavior

I did some throttle. A. Much slower sending rate. Where it seems that the loop is now waiting for datagrams to receive. 14:38:17:75747 ELAPSED 1293 ms 773 packages/sec 14:38:18:345807 ELAPSED 1270 ms 787 packages/sec 14:38:19:640996 ELAPSED 1294 ms 772 packages/sec B. Increasing the sending rate. Ho...
by Arjan
Tue Oct 16, 2012 6:51 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: GPIO performance
Replies: 7
Views: 2530

Re: GPIO performance

Thanks for your advice Gordon. I will look into the kernel drivers as well. On minor challenge for me; The D/A board has one MCP4922 and two MCP4902's. And I am using the 74HC139 for adding an additional /CS line. With the current kernel driver I can address the 'DAC12' (the MCP4922) and the 'DAC8-1...
by Arjan
Tue Oct 16, 2012 6:36 pm
Forum: C/C++
Topic: UDP listener different behavior
Replies: 2
Views: 1424

UDP listener different behavior

Hi, I notice a different behavior in a simple UDP listener c program. On one machine there is a UDP sender running generating UDP datagrams (packages) of 8 bytes. On two other machines; 1. ubuntu (x86) and 2 Raspberry Pi, there is the same listener running. See code snippet below. It seems that the ...
by Arjan
Tue Oct 16, 2012 3:26 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: GPIO performance
Replies: 7
Views: 2530

Re: GPIO performance

I initially started with python, but that was nowhere near fast enough. I switched to C, using the bcm2835 library by Mike McCauley, which massively improved things, but I still face the issue that I'm not pumping data out fast enough via the GPIO pins. Because the bit banging is done in compiled C...
by Arjan
Tue Oct 16, 2012 2:35 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: GPIO performance
Replies: 7
Views: 2530

Re: GPIO performance

Hi Mike, Please will you elaborate on your second remark? Both libraries are using /dev/mem for accessing the GPIO pins. The Shift Library is just a wrapper around digitalWrite. So I am wondering why wiringPi would deliver a better performance. Background : I am working on a 6 channel D/A SPI board ...
by Arjan
Fri Oct 12, 2012 6:25 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI driver latency and a possible solution
Replies: 241
Views: 134047

Re: SPI driver latency and a possible solution

Hi Martin, Thanks for this great work! This patch would be useful for the 6 channel D/A SPI board I am working on. Just asking a favor ; I have extended the two SPI CS lines with a third one by means of the 74HC139. Therefore I need the additional /dev/spidev-0.2 (were both CS lines are asserted). W...
by Arjan
Thu Oct 11, 2012 6:50 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: 74HC595 Shift Register IC Vcc
Replies: 16
Views: 11403

Re: 74HC595 Shift Register IC Vcc

To be save on the GPIO pins, I have added the 74HC244 Octal buffer/ line driver to the pins I am using to drive SPI slaves and led's at 5 volt. The 244 is basically the 3,3 volt to 5,0 volt bridge. For bidirectional signals, the 74HC245 could be an option. This 5 volt is coming from a different powe...
by Arjan
Wed Oct 10, 2012 5:07 pm
Forum: General programming discussion
Topic: Driver details for I2C,SPI and GPIO on Raspbian
Replies: 3
Views: 7420

Re: Driver details for I2C,SPI and GPIO on Raspbian

Hi,

Some pointers to start with :

I2C Installation for Raspberry Pi – Step by Step Guide
http://www.skpang.co.uk/blog/archives/575

and

Raspberry Pi Examples
http://www.robot-electronics.co.uk/htm/ ... amples.htm
by Arjan
Wed Oct 10, 2012 4:36 pm
Forum: Automation, sensing and robotics
Topic: Christmas lights
Replies: 6
Views: 3216

Re: Christmas lights

For DMX you might be interested in :
http://www.opendmx.net/index.php/OLA_Raspberry_Pi
by Arjan
Wed Oct 10, 2012 9:44 am
Forum: Networking and servers
Topic: Build a file server with the Raspberry Pi
Replies: 1
Views: 4469

Build a file server with the Raspberry Pi

We’ll be using Arch Linux as the operating system for our file server, because it is small,and has only the minimum packages required for a working system. This means that we can set up the file server without wasting resources on a graphical user interface and other unnecessary packages. Arch Linu...
by Arjan
Sat Sep 29, 2012 1:28 pm
Forum: General discussion
Topic: Xilinx FPGA expansion anyone?
Replies: 21
Views: 9983

Re: Xilinx FPGA expansion anyone?

With respect to D/A, the MCP4922 (http://ww1.microchip.com/downloads/en/DeviceDoc/22250A.pdf) might be of interest. The MCP4922 device is a dual channel 12-bit DAC which uses an external voltage reference. This device offers high accuracy and low power consumption, and is available in various packag...

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