NEC V850E/RS1, User Manual, Page: 483 / 852

483
Chapter 14 Queued CSI (CSI30, CSI31)
User’s Manual U16702EE3V2UD00
14.3.8 Description of the FIFO Buffer Transfer Mode
When the TRMD bit in the CSIM register is set “1”, the Queued CSI operates in FIFO buffer transfer
mode.
Figure 14-19: FIFO Buffer Transfer Mode Data Handling
Transfer start condition in FIFO buffer transfer mode:
[CTXE = 1 or CRXE = 1] and
[Data exists in FIFO (SFEMP = 0)]
The transmission data number must be set in SFN[3:0]. Note that writing a value greater than 16 to the
SFN register is prohibited, as the FIFO buffer design can hold up to 16 elements only.
The transfer starts by copying the first data element - pointed to by SIO Load/Store FIFO pointer - to the
SIO shift register. At that time the transmission status flag CSOT is set to “1”, and the CS3n[3:0] pins
output the CS value from the FIFO.
When the transfer of the data element is finished, the received data overwrites the location in the FIFO
using the SIO Load/Store FIFO pointer, and the SIO Load/Store FIFO pointer is then incremented.
INC
19 16 0
CS Data
3, 2, 1, 0 15, 14, 13, ...... 2, 1, 0
15
14
13
12
11
10
9
8
7
6
5
CS data 4 4
CS data 3 Transmission data 3 3
CS data 2 Transmission data 2 2
CS data 1 Transmission data 1 1
CS data 0 Transmission data 0 0
SFCS
3, 2, 1, 0
SFCS register
SFDB
15, 14, 13, ......2, 1, 0
SFDB register SFA register
INC
INC
Read FIFO
pointer
Write FIFO
pointer
CS3n3 to CS3n0 pins
SIO
SIRBE
SI3n pin
SO3n
SIRB
SFP
3, 2, 1, 0
SIO Load/Store
FIFO pointer
15
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