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McSPI Basic Programming Model
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Table 20-16. End-of-Transfer Sequences
Transmit Receive Transmit Only Receive Only
Interrupt DMA Interrupt DMA Interrupt DMA
Master normal End of See Section 20.6.2.3 See Section 20.6.2.4 See See See
transfer Section 20.6.2.4 Section Section 20.6.2.5.1
sequence 20.6.2.5.1
Minimum 1 1 1 1 1 1
number of
words
DMA transfer w w w – 1
size
(1)
Master turbo End of See Section 20.6.2.3 See Section 20.6.2.4 See See See
transfer Section 20.6.2.4 Section Section 20.6.2.5.2
sequence 20.6.2.5.2
Minimum 1 1 1 1 2 3
number of
words
DMA transfer w w w – 2
size
(1)
Slave End of See Section 20.6.2.3 See Section 20.6.2.4 See See Section 20.6.2.5.3
transfer Section 20.6.2.4
sequence
Minimum 1 1 1 1 1 1
number of
words
DMA transfer w w w w
size
(2)
(1)
w = number of words to transfer
(2)
w = number of words to transfer
The different sequences can be merged in one process to manage transfers of several types. The
end-of-transfer sequences are described from the start of the channel.
In these sequences and in later sections of this chapter, some software variables are used:
•
WRITE_COUNT (= 0 at initialization): Contains the number of words to transfer
• READ_COUNT (= 0 at initialization): Contains the number of words to receive
• CHANNEL_ENABLE (= false at initialization)
• LAST_TRANSFER (= false at initialization): Indicates that the last word is in transmission
• LAST_REQUEST (= false at initialization): Indicates that the last request is in progress
All variables are initialized before starting the channel.
3014 Multichannel SPI SWPU177N – December 2009 – Revised November 2010
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