V DMA BLOCK: IDMA (Intelligent DMA)
Successive transfer mode
The channels for which DMOD in control information is set to "01" operate in successive transfer mode.In this mode, a data transfer is performed by one trigger a number of times as set by the transfer counter. The transfer counter is decremented to "0" by one transfer executed.
The operation of IDMA in successive transfer mode is shown by the flow chart in Figure 3.2.
| START | A | |
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| Calculates address of | ||
| control information | Base address + (Channel number ⋅ 12) | |
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| Loads | channel | B (3 words) |
| control information | ||
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| C (Data read from source of transfer) |
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| Transfers one unit of data | ||
| D (Data write to destination of transfer) | ||
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| Transfer counter - 1 | E | |
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N | Transfer |
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| counter = 0 |
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| Y |
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| Saves channel | F (3 words) | |
| control information | ||
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| IDMA interrupt | processing |
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| (if interrupt is enabled) |
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END
Trigger
A | B1 B2 B3 C1 D1 E1 | Cn Dn En F1 F2 F3 |
Figure 3.2 Operation Flow in Successive Transfer Mode
(1)When a trigger is accepted, the address for control information is calculated from the base address and channel number.
(2)Control information is read from the calculated address into the internal temporary register.
(3)Data of the size set in the control information is read from the source address.
(4)The read data is written to the destination address.
(5)The address is incremented or decremented and the transfer counter is decremented.
(6)Steps (3) to (5) are repeated until the transfer counter reaches 0.
(7)The modified control information is written to RAM.
(8)In the case of a hardware trigger, the interrupt control bits are processed before completing IDMA.
Condition | Interrupt factor flag | IDMA request bit | IDMA enable bit |
Transfer counter ≠ "0": | Reset ("0") | Not changed ("1") | Not changed ("1") |
Transfer counter = "0", DINTEN = "1": | Not changed ("1") | Reset ("0") | Not changed ("1") |
Transfer counter = "0", DINTEN = "0": | Reset ("0") | Not changed ("1") | Reset ("0") |
S1C33210 FUNCTION PART | EPSON |