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DIRECT RAM INTERFACE (DRI)
14
14-13
32185/32186 Group Hardware Manual
Rev.1.10 REJ09B0235-0110 May 15, 07
14.2.3 DRI Transfer Control Register
DRI Transfer Control Register (DRITRMCNT)
<Address: H'0080 2006>
123456
b7
b0
DRST
DBST
ADST
ADMD
ADEV
000000
0
ADSL
0
<Upon exiting reset: H'00>
b
Bit Name
Function
R
W
0
DRST
0: Reset DRI
R
W
DRI reset bit
1: Enable operation
1
DBST
0: No data exists that has not been DRI transferred yet R
–
DRI buffer status bit
1: Data exists that has not been DRI transferred yet
2
ADST
0: DRI address counter 0 is active
R
–
Address counter status bit
1: DRI address counter 1 is active
3
ADMD
0: Continuous mode
R
W
Address counter operation mode select bit
1: Reload mode
4, 5
ADSL
00: Select DRI address counter 0
R
W
Address counter select bit
01: Select DRI address counter 1
10: Toggle between DRI address counters 0 and 1
11: Settings inhibited
6
No function assigned. Fix to "0."
00
7
ADEV
0: DRI transfer counter underflow
R
W
Address counter switchover select bit
1: DEC4 underflow
(1) DRST (DRI Reset) bit (Bit 0)
This is a software reset bit of the DRI control unit. No data captures nor DRI transfers are performed
while this bit = "0." This bit should be set to "1" to enable operation of the DRI. If this bit is cleared to
"0" while the DRI is operating, the DRI capture control unit and the DRI transfer control unit both are
initialized. Therefore, if any data exists in the DRI that has not been DRI transferred yet, all transfers
for that data are canceled, and data captures are not performed either.
The following lists the registers and bits that are affected by this bit:
1) ADST(Address counter status) bit
If the DRST bit is cleared to "0" while ADSL(address counter select) bits = "10" (DRI address counters
0/1 toggled), the DRI address counter 0(DRIADR0CT) is activated and ADST bit is cleared to "0."
2) DRST(DRI buffer status) bit
If the DRST bit is cleared to "0," this status bit is initialized to "0."
3) DRI transfer counter(DRITRMCT)
If the DRST bit is cleared to "0," the DRI transfer counter(DRITRMCT) is initialized to "0."
Notes: DIN input processing control and DEC0–4 operations are not affected by setting or
clearing the DRST bit.
If the DRST bit changes state from "0" to "1" or vice versa, a finite time of 4 BCLKs is
required before the new state takes effect. Changing the DRST bit again during that
time is prohibited.
If the DRST bit is set or cleared, a finite time of 1 BCLK is required before ADST bit
and DBST bit are initialized.
Changing any of ADMD(address counter operation mode select) bit, ADSL (address
counter select) bit or ADVEN(address counter switchover select) bit while the DRST
bit = "1" is prohibited.
(2) DBST (DRI Buffer Status) bit (Bit 1)
This bit indicates whether the internal DRI buffer contains any data that has not been DRI transferred yet.
In order to avoid the data loss of Data transfer, middle buffer for 32 bits × 4 row is embedded in the
inside of DRI. If the data is in this middle buffer, DBST bit shows “1.” If it is not DBST bit shows “0”
Also, when DRST bit is “0” cleared DBST bit is cleared as well.
14.2 DRI Related Registers