HD6417615 Hitachi Semiconductor, HD6417615 Datasheet - Page 491

• Manufacturer Part Number: HD6417615
• Description: Hardware Manual
• Manufacturer: Hitachi Semiconductor

Round-Robin Mode: Switches the priority of channel 0 and channel 1, shifting their ability to
receive transfer requests. Each time one transfer ends on one channel, the priority shifts to the
other channel. The channel on which the transfer just finished is assigned low priority. After reset,
channel 1 has higher priority than channel 0.
Figure 11.5 shows how the priority changes when channel 0 and channel 1 transfers are requested
simultaneously and another channel 0 transfer is requested after the first two transfers end. The
DMAC operates as follows:
1. Transfer requests are generated simultaneously to channels 1 and 0.
2. Channel 1 has the higher priority, so the channel 1 transfer begins first (channel 0 waits for
3. When the channel 1 transfer ends, channel 1 becomes the lower-priority channel.
4. The channel 0 transfer begins.
5. When the channel 0 transfer ends, channel 0 becomes the lower-priority channel.
6. A channel 0 transfer is requested.
7. The channel 0 transfer begins.
8. When the channel 0 transfer ends, channel 0 is already the lower-priority channel, so the order
476
transfer).
remains the same.