bcm2835 library提供了user space 操作IO的代码。
本文不涉及代码分析，先直观的按照user guide完成操作。
1. 在Raspberry中安装bcm2835 library
2. build LED test
3. run led test
- 从http://www.airspayce.com/mikem/bcm2835/ 下载library库，可以直接在树莓派中下载或者宿主机上下载后sftp传给树莓派，
- 解压缩
pi@raspberrypi:~ $ tar zxvf bcm2835-1.56.tar.gz bcm2835-1.56/ bcm2835-1.56/configure.ac bcm2835-1.56/COPYING bcm2835-1.56/examples/ bcm2835-1.56/examples/spi/ bcm2835-1.56/examples/spi/spi.c bcm2835-1.56/examples/input/ bcm2835-1.56/examples/input/input.c bcm2835-1.56/examples/event/ bcm2835-1.56/examples/event/event.c bcm2835-1.56/examples/pwm/ bcm2835-1.56/examples/pwm/pwm.c bcm2835-1.56/examples/gpio/ bcm2835-1.56/examples/gpio/gpio.c bcm2835-1.56/examples/blink/ bcm2835-1.56/examples/blink/blink.c bcm2835-1.56/examples/spin/ bcm2835-1.56/examples/spin/spin.c bcm2835-1.56/examples/i2c/ bcm2835-1.56/examples/i2c/i2c.c bcm2835-1.56/config.guess bcm2835-1.56/NEWS bcm2835-1.56/depcomp bcm2835-1.56/configure bcm2835-1.56/aclocal.m4 bcm2835-1.56/compile bcm2835-1.56/INSTALL bcm2835-1.56/Makefile.in bcm2835-1.56/missing bcm2835-1.56/config.sub bcm2835-1.56/Makefile.am bcm2835-1.56/ChangeLog bcm2835-1.56/README bcm2835-1.56/install-sh bcm2835-1.56/config.h.in bcm2835-1.56/src/ bcm2835-1.56/src/test.c bcm2835-1.56/src/bcm2835.h bcm2835-1.56/src/bcm2835.c bcm2835-1.56/src/Makefile.in bcm2835-1.56/src/Makefile.am bcm2835-1.56/ltmain.sh bcm2835-1.56/AUTHORS bcm2835-1.56/doc/ bcm2835-1.56/doc/Doxyfile.in bcm2835-1.56/doc/Makefile.in bcm2835-1.56/doc/Makefile.am bcm2835-1.56/test-driver
- ./configure
pi@raspberrypi:~/bcm2835-1.56 $ ls aclocal.m4 ChangeLog config.guess config.sub configure.ac depcomp examples install-sh Makefile.am missing README test-driver AUTHORS compile config.h.in configure COPYING doc INSTALL ltmain.sh Makefile.in NEWS src pi@raspberrypi:~/bcm2835-1.56 $ ./configure checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... no checking for mawk... mawk checking whether make sets $(MAKE)... yes checking whether make supports nested variables... yes checking for style of include used by make... GNU checking for gcc... gcc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... no checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking whether gcc understands -c and -o together... yes checking dependency style of gcc... gcc3 checking for clock_gettime in -lrt... yes checking for doxygen... no configure: WARNING: Doxygen not found - continuing without Doxygen support checking for ranlib... ranlib checking for gcc... (cached) gcc checking whether we are using the GNU C compiler... (cached) yes checking whether gcc accepts -g... (cached) yes checking for gcc option to accept ISO C89... (cached) none needed checking whether gcc understands -c and -o together... (cached) yes checking dependency style of gcc... (cached) gcc3 checking that generated files are newer than configure... done configure: creating ./config.status config.status: creating Makefile config.status: creating src/Makefile config.status: creating doc/Makefile config.status: creating config.h config.status: executing depfiles commands
- make
pi@raspberrypi:~/bcm2835-1.56 $ make make all-recursive make[1]: Entering directory '/home/pi/bcm2835-1.56' Making all in src make[2]: Entering directory '/home/pi/bcm2835-1.56/src' gcc -DHAVE_CONFIG_H -I. -I.. -g -O2 -MT bcm2835.o -MD -MP -MF .deps/bcm2835.Tpo -c -o bcm2835.o bcm2835.c mv -f .deps/bcm2835.Tpo .deps/bcm2835.Po rm -f libbcm2835.a ar cru libbcm2835.a bcm2835.o ar: `u' modifier ignored since `D' is the default (see `U') ranlib libbcm2835.a make[2]: Leaving directory '/home/pi/bcm2835-1.56/src' Making all in doc make[2]: Entering directory '/home/pi/bcm2835-1.56/doc' make[2]: Nothing to be done for 'all'. make[2]: Leaving directory '/home/pi/bcm2835-1.56/doc' make[2]: Entering directory '/home/pi/bcm2835-1.56' make[2]: Leaving directory '/home/pi/bcm2835-1.56' make[1]: Leaving directory '/home/pi/bcm2835-1.56' pi@raspberrypi:~/bcm2835-1.56 $ sudo make check Making check in src make[1]: Entering directory '/home/pi/bcm2835-1.56/src' make test make[2]: Entering directory '/home/pi/bcm2835-1.56/src' gcc -DHAVE_CONFIG_H -I. -I.. -g -O2 -MT test.o -MD -MP -MF .deps/test.Tpo -c -o test.o test.c mv -f .deps/test.Tpo .deps/test.Po gcc -g -O2 -o test test.o ./libbcm2835.a -lrt make[2]: Leaving directory '/home/pi/bcm2835-1.56/src' make check-TESTS make[2]: Entering directory '/home/pi/bcm2835-1.56/src' make[3]: Entering directory '/home/pi/bcm2835-1.56/src' PASS: test ============================================================================ Testsuite summary for bcm2835 1.56 ============================================================================ # TOTAL: 1 # PASS: 1 # SKIP: 0 # XFAIL: 0 # FAIL: 0 # XPASS: 0 # ERROR: 0 ============================================================================ make[3]: Leaving directory '/home/pi/bcm2835-1.56/src' make[2]: Leaving directory '/home/pi/bcm2835-1.56/src' make[1]: Leaving directory '/home/pi/bcm2835-1.56/src' Making check in doc make[1]: Entering directory '/home/pi/bcm2835-1.56/doc' make[1]: Nothing to be done for 'check'. make[1]: Leaving directory '/home/pi/bcm2835-1.56/doc' make[1]: Entering directory '/home/pi/bcm2835-1.56' make[1]: Leaving directory '/home/pi/bcm2835-1.56'
- sudo make install
pi@raspberrypi:~/bcm2835-1.56 $ sudo make install Making install in src make[1]: Entering directory '/home/pi/bcm2835-1.56/src' make[2]: Entering directory '/home/pi/bcm2835-1.56/src' /bin/mkdir -p '/usr/local/lib' /usr/bin/install -c -m 644 libbcm2835.a '/usr/local/lib' ( cd '/usr/local/lib' && ranlib libbcm2835.a ) /bin/mkdir -p '/usr/local/include' /usr/bin/install -c -m 644 bcm2835.h '/usr/local/include' make[2]: Leaving directory '/home/pi/bcm2835-1.56/src' make[1]: Leaving directory '/home/pi/bcm2835-1.56/src' Making install in doc make[1]: Entering directory '/home/pi/bcm2835-1.56/doc' make[2]: Entering directory '/home/pi/bcm2835-1.56/doc' make[2]: Nothing to be done for 'install-exec-am'. make[2]: Nothing to be done for 'install-data-am'. make[2]: Leaving directory '/home/pi/bcm2835-1.56/doc' make[1]: Leaving directory '/home/pi/bcm2835-1.56/doc' make[1]: Entering directory '/home/pi/bcm2835-1.56' make[2]: Entering directory '/home/pi/bcm2835-1.56' make[2]: Nothing to be done for 'install-exec-am'. make[2]: Nothing to be done for 'install-data-am'. make[2]: Leaving directory '/home/pi/bcm2835-1.56' make[1]: Leaving directory '/home/pi/bcm2835-1.56' pi@raspberrypi:~/bcm2835-1.56 $
- build LED test 并执行
pi@raspberrypi:~/Pioneer600 $ cd LED/ pi@raspberrypi:~/Pioneer600/LED $ ls bcm2835 fs python shell wiringPi pi@raspberrypi:~/Pioneer600/LED $ cd bcm2835/ pi@raspberrypi:~/Pioneer600/LED/bcm2835 $ ls led led.c Makefile pi@raspberrypi:~/Pioneer600/LED/bcm2835 $ make make: 'led' is up to date. pi@raspberrypi:~/Pioneer600/LED/bcm2835 $ ./led bcm2835_init: Unable to open /dev/mem: Permission denied pi@raspberrypi:~/Pioneer600/LED/bcm2835 $ sudo ./led
LED代码
/* LED.c * you can build this with something like: * gcc -Wall blink.c -o blink -lbcm2835 * sudo ./blink */ #include <bcm2835.h> #define PIN 26 int main(int argc, char **argv) { if (!bcm2835_init())return 1; bcm2835_gpio_fsel(PIN, BCM2835_GPIO_FSEL_OUTP); while (1) { bcm2835_gpio_write(PIN, HIGH); bcm2835_delay(500); bcm2835_gpio_write(PIN, LOW); bcm2835_delay(500); } bcm2835_close(); return 0; }可以看到LED blink.