Section 14 Direct Memory Access Controller (DMAC)
Rev.1.00 Dec. 13, 2005 Page 604 of 1286
REJ09B0158-0100
14.4.5 Repeat
Mode
Transfer
In a repeat mode transfer, a DMA transfer is repeated without specifying the transfer settings
every time before executing a transfer.
Using a repeat mode transfer with the half end function allows a double buffer transfer executed
virtually. Following processings can be executed effectively by using a repeat mode transfer. As
an example, operation of receiving voice data from the VOICE CODEC and compressing it is
explained.
In the following example, processing of compressing 40-word voice data every data reception is
explained. In this case, it is assumed that voice data is received by means of SIOF.
1. DMAC settings
•
Set address of the SIOF receive data register in SAR
•
Set address of an internal memory data store area in DAR
•
Set TCR to H
'
50 (80 times)
•
Satisfy the following settings of CHCR
Bits RPT[2:0] = B
'
010: Repeat mode (use DAR as a repeat area)
Bit HIE = B
'
1: TCR/2 interrupt generated
Bits DM[1:0] = B
'
01: DAR incremented
Bits SM[1:0] = B
'
00: SAR fixed
Bit IE = B
'
1: Interrupt enabled
Bit DE = B
'
1: DMA transfer enabled
•
Set such as bits TB and TS[2:0] according to use conditions
•
Set bits CMS[1:0] and PR[1:0] in DMAOR according to use conditions and set the DME bit to
B
'
1
2. Voice data is received and then transferred by SIOF/DMAC
3. TCR is decreased to half of its initial value and an interrupt is generated
After reading CHCR to confirm that the HE bit is set to 1 by an interrupt processing, clear the
HE bit to 0 and compress 40-word voice data from the address set in DAR.
4. TCR is cleared to 0 and an interrupt is generated
After reading CHCR to confirm that the TE bit is set to 1 by an interrupt processing, clear the
TE bit to 0 and compress 40-word voice data from the address set in DAR
+
40. After this
operation, the value of DARB is copied to DAR in DMAC and initialized, and the value of
TCRB is copied to TCR and initialized to 80.
5. Hereafter, steps 2 and 4 are repeated until the DME or DE bit is cleard to 0, or an NMI
interrupt is generated. Note that if the HE bit is not cleared in the procedure 3 or if the TE bit is
Summary of Contents for SH7780 Series
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Page 50: ...Rev 1 00 Dec 13 2005 Page l of l ...
Page 82: ...Section 1 Overview Rev 1 00 Dec 13 2005 Page 32 of 1286 REJ09B0158 0100 ...
Page 122: ...Section 3 Instruction Set Rev 1 00 Dec 13 2005 Page 72 of 1286 REJ09B0158 0100 ...
Page 146: ...Section 4 Pipelining Rev 1 00 Dec 13 2005 Page 96 of 1286 REJ09B0158 0100 ...
Page 196: ...Section 6 Floating Point Unit FPU Rev 1 00 Dec 13 2005 Page 146 of 1286 REJ09B0158 0100 ...
Page 292: ...Section 9 L Memory Rev 1 00 Dec 13 2005 Page 242 of 1286 REJ09B0158 0100 ...
Page 492: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Dec 13 2005 Page 442 of 1286 REJ09B0158 0100 ...
Page 674: ...Section 15 Clock Pulse Generator CPG Rev 1 00 Dec 13 2005 Page 624 of 1286 REJ09B0158 0100 ...
Page 692: ...Section 16 Watchdog Timer and Reset Rev 1 00 Dec 13 2005 Page 642 of 1286 REJ09B0158 0100 ...
Page 726: ...Section 18 Timer Unit TMU Rev 1 00 Dec 13 2005 Page 676 of 1286 REJ09B0158 0100 ...
Page 1032: ...Section 25 Audio Codec Interface HAC Rev 1 00 Dec 13 2005 Page 982 of 1286 REJ09B0158 0100 ...
Page 1150: ...Section 28 General Purpose I O GPIO Rev 1 00 Dec 13 2005 Page 1100 of 1286 REJ09B0158 0100 ...
Page 1184: ...Section 29 User Break Controller UBC Rev 1 00 Dec 13 2005 Page 1134 of 1286 REJ09B0158 0100 ...
Page 1266: ...Section 31 Electrical Characteristics Rev 1 00 Dec 13 2005 Page 1216 of 1286 REJ09B0158 0100 ...
Page 1328: ...Appendix Rev 1 00 Dec 13 2005 Page 1278 of 1286 REJ09B0158 0100 ...
Page 1336: ...Rev 1 00 Dec 13 2005 Page 1286 of 1286 REJ09B0158 0100 ...
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