These items are supplied within that header file for backward compatibility reasons only, so old source code that has been written for previous library versions could easily be maintained until its end-of-life. Use of any of these items in new code is strongly discouraged.
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Allowing specific system-wide interrupts |
In addition to globally enabling interrupts, each device's particular interrupt needs to be enabled separately if interrupts for this device are desired. While some devices maintain their interrupt enable bit inside the device's register set, external and timer interrupts have system-wide configuration registers.
Example:
- Note:
- Be careful when you use these functions. If you already have a different interrupt enabled, you could inadvertantly disable it by enabling another intterupt.
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#define | enable_external_int(mask) (__EICR = mask) |
#define | INTERRUPT(signame) |
#define | __INTR_ATTRS used |
static __inline__ void | timer_enable_int (unsigned char ints) |
Obsolete IO macros |
Back in a time when AVR-GCC and avr-libc could not handle IO port access in the direct assignment form as they are handled now, all IO port access had to be done through specific macros that eventually resulted in inline assembly instructions performing the desired action.
These macros became obsolete, as reading and writing IO ports can be done by simply using the IO port name in an expression, and all bit manipulation (including those on IO ports) can be done using generic C bit manipulation operators.
The macros in this group simulate the historical behaviour. While they are supposed to be applied to IO ports, the emulation actually uses standard C methods, so they could be applied to arbitrary memory locations as well.
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#define | inp(port) (port) |
#define | outp(val, port) (port) = (val) |
#define | inb(port) (port) |
#define | outb(port, val) (port) = (val) |
#define | sbi(port, bit) (port) |= (1 << (bit)) |
#define | cbi(port, bit) (port) &= ~(1 << (bit)) |