SH7727 Datasheet, PDF (691/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 20 Serial IO (SIOF)
Bits 15 to 13—Transmit FIFO Water Mark (TFWM2 to TFWM0): The transfer request of the
transmit FIFO is controlled by TDREQ bit of SISTR register. FIFO depth is always 16 steps,
nevertheless the setting to these bits.
Bit 15:
TFWM2
0
1
Bit 14:
TFWM1
0
1
Bit 13:
TFWM0
0
0
1
0
1
Description
The transfer request is submitted when the size of empty
area in transmit FIFO is 16 steps
(Initial value)
The transfer request is submitted when the size of empty
area in transmit FIFO is larger than 12 steps
The transfer request is submitted when the size of empty
area in transmit FIFO is larger than 8 steps
The transfer request is submitted when the size of empty
area in transmit FIFO is larger than 4 steps
The transfer request is submitted when the size of empty
area in transmit FIFO is larger than 1 step
Bits 7 to 5—Receive FIFO Water Mark (RFWM2 to RFWM0): The transfer request of the
receive FIFO is controlled by TDREQ bit of SISTR register. FIFO depth is always 16 steps,
nevertheless the setting to these bits.
Bit 7:
RFWM2
0
1
Bit 6:
RFWM1
0
1
Bit 5:
RFWM0
0
0
1
0
1
Description
The transfer request is submitted when the size of empty
area of receive FIFO is larger than 1 step
(Initial value)
The transfer request is submitted when the size of empty
area of receive FIFO is larger than 4 steps
The transfer request is submitted when the size of empty
area of receive FIFO is larger than 8 steps
The transfer request is submitted when the size of empty
area of receive FIFO is larger than 12 steps
The transfer request is submitted when the size of empty
area of receive FIFO is at 16 steps
Bits 12 to 8—Transmit FIFO Usable Area (TFUA4 to TFUA0): TFUA shows usable number
of words for CPU or DMAC to transfer from 00000 to 10000 (initial value).
Bits 4 to 0—Receive FIFO Usable Area (RFUA4 to RFUA0): RFUA shows usable number of
words for CPU or DMAC to transfer from 00000 (initial value) to 10000.
Rev. 5.00 Dec 12, 2005 page 619 of 1034
REJ09B0254-0500