GPIO using "bcm2835.h"

[Cornetto]

Hi,

I'm trying to use the GPIO in C/C++ but i'm facing some (probably trivial) problem. I (think I) have installed "bcm2835-1.8" according to http://www.open.com.au/mikem/bcm2835/ and I can successfully compile blink.c with

Code: Select all

gcc -o blink blink.c -l bcm2835

But when I run it "nothing" happens (a new line in the terminal is appended and the cursor moves there nothing else). I've tried adding a "printf("test");" on the first line in main but that doesn't display. Anyone got some ideas?

Thanks in advance!

[ksangeelee]

Using printf() without a newline, stdout won't flush immediately, so add fflush(stdout) afterwards to get it to display. Also, I find starting the string with '\r' (carriage-return) can be useful to stop scrolling and screen-fill, since each string will overwrite the last.

I wrote a simple utility to dump the status of the GPIO pins (link here) which might be useful for determining if the pins are configured correctly (e.g. not on ALT functions).

[Cornetto]

Stupid of me to forget the newline. The application probably works then, didn't bother to actually measure the pin when I couldn't get the test message written.

Thanks for your help and the link!

[pygmy_giant]

Hi

I'm having trouble installing this library

I have tried following the instructions on this page: http://www.open.com.au/mikem/bcm2835/index.html

by typing: ./configure make # as root: make check make install

but get a 'permission denied' error despite doing so as a super user

Any help appreciated

[benyang]

Hi

I'm having trouble installing this library

I have tried following the instructions on this page: http://www.open.com.au/mikem/bcm2835/index.html

by typing: ./configure make # as root: make check make install

but get a 'permission denied' error despite doing so as a super user

Any help appreciated

extract bcm2835-1.xx.tar.gz in home directory
$ sh ./configure
$ make
$ sudo make check
$ sudo make install

it works for me

[brucepi]

if you want to use the Python extension for libbcm2835, the correct procedure is like this:
first go and install the C library from this link and according to the instruction explained:
http://www.airspayce.com/mikem/bcm2835/
tar zxvf bcm2835-1.xx.tar.gz
cd bcm2835-1.xx
(run as root i.e su root)
./configure
make
sudo make check
sudo make install

second go to: https://pypi.python.org/pypi/PyBCM2835/0.1.0
download the package: https://pypi.python.org/packages/7b/d4/ ... 1.0.tar.gz (it may change while you are downloading so just downlaod the available version)
and according to the same site instruction take the following steps one by one:
tar xvfz bcm2835-1.22.tar.gz cd bcm2835-1.22/src
make libbcm2835.a gcc -shared bcm2835.o -o libbcm2835.so
sudo cp libbcm2835.so /usr/local/lib/
sudo cp bcm2835.h /usr/local/include/