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by jdj
Mon Jun 11, 2012 8:27 am
Forum: Automation, sensing and robotics
Topic: Parallax PING))) ?
Replies: 21
Views: 12758

Re: Parallax PING))) ?

Thanks for the replies! Klappy : Do you mean that you have an 142us inaccuracy? I.e. difference between repeated measurements of the same distance? That would mean ~2.5cm distance inaccuracy which I could live with. I will order a pair and try them out; the seeedstudio ones are just ~€15, so if they...
by jdj
Mon Jun 11, 2012 8:17 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: i2c pull up resistors
Replies: 6
Views: 20981

Re: i2c pull up resistors

Ah - the RPi has 1.8k pullups and not 8k (of course)... This makes it even lower, parallell resistance (10k + 1.8k) is then 1.5k. According to an I2C spec file I have from Philips, the minimum allowed for a 3.3V system is somewhere around 1k... that ought to work in other words. I also see that 10k ...
by jdj
Sun Jun 10, 2012 1:09 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: i2c pull up resistors
Replies: 6
Views: 20981

Re: i2c pull up resistors

I am thinking of using the Adafruit BSS138 quad logic converter http://www.adafruit.com/products/757 to translate 5V systens to 3.3V. However it states that "This breakout has 4 BSS138 FETs with 10K pullups."... 10k pull up in parallel with the RPi 8k pull-ups would result in a 4.5k pull-up total; w...
by jdj
Sat Jun 09, 2012 6:24 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Concurrent processes/threads
Replies: 4
Views: 3601

Re: Concurrent processes/threads

Just my $0.02; This is what drivers are for (amongst other things); to give programs/processes/threads/<insert your name here> access to common, shared resources. Usually a thread interfaces with a driver by requiring the program/thread/etc to ask the driver for access (for instance using 'open'). T...
by jdj
Wed Jun 06, 2012 10:18 pm
Forum: Automation, sensing and robotics
Topic: Parallax PING))) ?
Replies: 21
Views: 12758

Parallax PING))) ?

Hi there Forum, I have a small robotics project in mind. In this I need some distance measurements and I thought that the ever used Sharp IR range sensors would do the trick (together with an ADC of course). However I stumbled on the Parallax PING))) ultrasonic range finder which has an impressive ...
by jdj
Wed Jun 06, 2012 10:43 am
Forum: Automation, sensing and robotics
Topic: Would like to control some motors, but where to start? Help
Replies: 21
Views: 8560

Re: Would like to control some motors, but where to start? H

Hi Just my $0.02; I have a similar project in mind - and similar experience I bought a "Graupner Punisher Rock crawler" for this purpose; 1 - It was on sale :) 2 - It has electronic motor control; the whole car is controlled by servo signals only - no mechanical throttle parts. 3 - When I take off t...
by jdj
Mon Dec 26, 2011 5:23 pm
Forum: Off topic discussion
Topic: Reading the forums on an iPhone...
Replies: 4
Views: 1232

Re: Reading the forums on an iPhone...

...is not easy. Is there anything I have missed?

I can only see (I guess) 75% of the page width, which means that I can't read it... :(

I can't resize the page either (to see more text).

Cheers!
/ Daniel

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