2.4 IIR Filter DSP Unit
84
Chapter 2: Hardware Configuration
(2) MCCR (Sum-of-products control/continue register)
[Bit15-10] These bits are not used. Read values are undefined. Any values written are invalid.
[Bit 9, 8] These bits are reserved. The reset value is '0.' Write values must always be '0.'
[Bit 7] OVF (OVer Flow bit)
This is the overflow bit. The OVF bit is set to '1' to indicate overflow in the results of 16-bit (DIV
bit) sum-of-products calculation. Note that this bit will not be set to '1' when RND=DLP=0. The
value is reset to 0 by executing a reset, or by writing '0' to this bit.
This bit has a read value of '1' for read-modify-write instructions.
[Bit 6, 5, 4] CNTD, CNTC, CNTB (CoNTinue bits)
The value '1' is written to these bits to specify that completion of a calculation is followed by contin-
uous calculations.
Each bit can be used to execute calculations on successive banks.
The CNTB bit signifies that calculations on A bank will be followed by calculations on B bank.
The CNTC bit signifies that calculations on B bank will be followed by calculations on C bank.
The CNTD bit signifies that calculations on C bank will be followed by calculations on D bank.
Thus, the CTNB, CTNC and CTND bits may be used in combination to designate various types of
processing as follows.
A
→B→C→D
(CNTB=CNTC=CNTD=1)
A
→B→C, D
(CNTB=CNTC=1,CNTD=0)
A
→B, C→D
(CNTB=CNTD=1,CNTC=0)
A, B
→C→D
(CNTB=0,CNTC=CNTD=1)
The CNTB-CNTD bits are set to 0 by a reset or by writing '0.'
The CNTB-CNTD bits should not be changed during execution.
Each of these bits has a read value of '1' for read-modify-write instructions.
[Bit 3, 2, 1, 0] CDRA-CDRD (Calculated data ready)
The CDRA-CDRD bits are set to 0 by a reset or by writing '0.'
The value '1' is not valid when written to the CDRA-CDRD bits. When sum-of-products calcula-
tions in a bank are ended, the DSP unit automatically writes '1' to the corresponding bit in the corre-
sponding bank. In continuous operation, each of the CDR bits is set when the corresponding
calculation is completed.
Address 00 0083 H
Initial value
––––
––
Reserved Reserved
---- --00 B
15
14
13
12
10
9
11
8
R/W
Address 00 0082 H
Initial value
OVF
CNTD CNTC CNTB CDRD CDRC CDRB CDRA
0000 0000 B
765
4
2
1
30
R/W