NEC V850E/RS1, User Manual, Page: 490 / 852

490
Chapter 14 Queued CSI (CSI30, CSI31)
User’s Manual U16702EE3V2UD00
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)
CPU Data Write
QCSI Buffer
pointer for write
QCSI pointer for
SIO load operation
:
SFFUL
SFDB write SFDB or SFCS write
Transmit buffer -n
Transmit buffer -n+15
INTC3nO
f
QCSI
data 15
data 16
n + 15
n
n + 1
n
data 0
data 15
Transmission of data 0 is
completed and space is
created in Transmit Buffer
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