Specifications

33
Atomic Handlers
The interrupts of an MCU must be used to handle communication transfers, to queue
up tasks called on by the devices environ ment, and to service an intern al device need. All
of these operations must be fast (< 1ms) and must not be interruptible. The events that
fall under this designation are:
• ZigBee Communications- Any form of communication between the ZigBee Radio
and this device must use this handler. This r ou tine must work with this interface
on the byte and packet level. Wh en a packet is ready to b e s erviced, it must then
schedule the appropriate task to service the packet.
• Serial Communications- Any form of communication coming through the serial
port must use th is handler. This routine must work with this interface on the byte
and packet level. When a packet is ready to be serviced, it must then schedule the
appropriate task to service the packet.
• Serial Ca ble Detect- When a valid connection is made using a serial cable, this
handler must ready the processor for communications by registering required power
modes with the system. When the cable is disconnected, this handler must remove
the imposed power modes and allow the s ystem to sleep.
• Removable Flash Detect- When an insertion or ejection event is detected, this
handler must be called to either setup or clean up the card and file system status
registers.
• Push-Button and De- bounce- When a button press is detected, this hand ler must
observe the triggered signal for a reasonable de-bounce period after which it must
schedule the appropriate task with the OS.