Transmit Buffer Overflow Interrupt Signal (Intc3No) - NEC V850E/RS1 User Manual

Chapter 14 Queued CSI (CSI30, CSI31)

14.3.12 Transmit Buffer Overflow Interrupt Signal (INTC3nO)

When the transmit FIFO buffer contains 16 elements, writing a 17th chip-select data (SFCS write) or
transfer data (SFDB write) results in the generation of the overflow interrupt INTC3nO. For the 17th
item, both chip-select and transfer data values are discarded.
The transmit FIFO buffer contains 16 elements if the FIFO pointer value for the write operation equals
the FIFO pointer value for the SIO load operation plus 15. When the transfer is completed and the FIFO
buffer pointer for the SIO load operation is incremented, space for one element is available again in
transmit buffer.
Figure 14-24: Transmit Buffer Overflow Interrupt Signal (INTC3nO)
f
QCSI
CPU Data Write
data 15 data 16
QCSI Buffer
n
n + 15
pointer for write
QCSI pointer for
n
n + 1
SIO load operation
data 0
Transmit buffer -n
Transmission of data 0 is
completed and space is
:
created in Transmit Buffer
Transmit buffer -n+15 data 15
INTC3nO
SFFUL
SFDB write SFDB or SFCS write
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User's Manual U16702EE3V2UD00
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