NEC mPD98409, Вопросы и ответы

Страница: 22 / 43

CHAPTER 6 TRANSMISSION SCHEDULER
Information S14769EJ1V0IF00
22
Q.6.6
What is the relationship between cell transmission scheduling and DMA operations?
A.6.6
The
µ
PD98409 determines the cell to be transmitted every 24 clocks by using the scheduler. After the cell to be
transmitted has been determined, a DMA operation to read the cell data is executed. If the transmit FIFO has
become full, the DMA operation to read cell data is stopped.
Reference:
µ
PD98409 User’s Manual 5.4.4 (7) Algorithm operation
Q.6.7
Does the host CPU have to set the A bit of the scheduler register?
A.6.7
The A bit of the scheduler register is managed or changed by the
µ
PD98409. It is not necessary for the host CPU
to rewrite this bit. The host CPU must set the A bit only when a shaper is used as an unassigned cell generator.
Reference:
µ
PD98409 User’s Manual 5.4.4 (4) Scheduler register