Flashes the Red, Green and Blue diodes on the board, in order. The system clock
starts at 80MHz.
Pressing SW2 toggles the system clock between 80MHz, 57MHz, 40MHz ,20MHz, and
16MHz by changing the PLL divisor.
Pressing SW1 bypasses the PLL completely, and runs off the raw 16MHz clock
provided by the external crystal oscillator.
The LEDs will toggle at different speeds, depending on the system clock. The
system clock changes are handled within the interrupt service routine.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Instead of setting and clearing RGB pins by PINx constants, define more readable
constants such as RGB_RED, and RGB_PORT.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
The LM4F provides new registers for system control. Each peripheral
now has its own clock gating control register. The LM4F still supports
the legacy registers for backwards compatibility.
Use SYSCTL_RCGCGPIO instead of SYSCTL_RCGC to enable the GPIO.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Specify the -mfloat-abi=hard and -mfpu=fpv4-sp-d16 flags so that FPU
is enabled by default.
While this compiles with FPU support, in order to use the floating point types,
the FPU must be explicitly enabled at runtime.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Fix three distinct issues were present with
examples/lm4f/Makefile.include:
1. Architecture flags were not being passed to the linker. This caused the linker
to link against the wrong libraries when trying to use any C library, causing
hard faults.
2. -lc and -lnosys were not linked against. Try using printf() without -lnosys
3. The makefile erroneously specified -mcpu=cortex-m3 instead of m4.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
