TWR-K60N512-KEIL Freescale Semiconductor, TWR-K60N512-KEIL Datasheet - Page 74

• Manufacturer Part Number: TWR-K60N512-KEIL
• Description: K60N512 Keil Tower Kit
• Manufacturer: Freescale Semiconductor
• Series: Kinetisr
• Type: MCUr

Specifications of TWR-K60N512-KEIL

• Rohs Compliant: YES
• Contents: 4 Boards, Documentation, DVD
• Peak Reflow Compatible (260 C): Yes
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: Freescale Tower System, K60N512

Transfer process—major and minor transfer loop
transfer request is asserted to a channel of a higher priority. The lower priority channel
halts its transfer on completion of the current read/write operation and allows the channel
of higher priority to work.
In round robin mode, the eDMA cycles through the channels from the highest to the
lowest, checking for a pending request. When a channel with a pending request is
reached, it is allowed to perform its transfer. After the transfer has been completed, the
eDMA continues to cycle through the channels looking for the next pending request.
7.3 Transfer process—major and minor transfer loop
Each channel requires a 32-byte transfer control descriptor (TCD) for defining the desired
data movement operation. The channel descriptors are stored in the eDMA local memory
in sequential order.
Each time a channel is activated and executes, n bytes are transferred from the source to
the destination. This is referred to as a minor transfer loop. A major transfer loop consists
of a number of minor transfer loops, and this number is specified within the TCD. As
iterations of the minor loop are completed, the current iteration (CITER) TCD field is
decremented. When the current iteration field has been exhausted, the channel has
completed a major transfer loop.
Figure 7-6
shows the relationship between major and
minor loops. In this example a channel is configured so that a major loop consists of three
iterations of a minor loop. The minor loop is configured as a transfer of 4 bytes.
Kinetis Quick Reference User Guide, Rev. 0, 11/2010
74
Freescale Semiconductor