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R01UH0336EJ0102 Rev.1.02
Page 231 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 5 DMA Module
Figure 5-5
Example of Single Transfer (128 Bits, DMA Channel Priority: CH0 (High) >
CH1 (Low))
(2)
Single-Step Transfer Mode (when Software DMA Transfer Request Is
Generated)
When a software DMA transfer request is acknowledged, the amount of data
specified as the unit of data transfer (8, 16, 32, or 128 bits) is transferred. Each
time transfer of this amount is executed, the bus is released and the DMA
controller waits for a DMA transfer request. The acknowledge n signal (n = 7 to
0), which indicates that a hardware DMA transfer request has been
acknowledged is not output at this time.
Once a software DMA transfer request has been acknowledged, this operation
is repeated the number of times specified in DMA transfer count register n
(DTCn) (n = 7 to 0). Priority is determined each time transfer is executed, so a
DMA cycle for a channel having a higher priority may interrupt transfer in
response to a software DMA request.
Figure 5-6
Example of Single-Step Transfer (8/16/32 Bits, DMA Channel Priority:
CH0 (High) > CH1 (Low))
DMA1
Read
DMA1
Read
DMA1
Read
DMA0
Read
DMA1
Read
DMA1
Write
DMA1
Write
DMA1
Write
DMA1
Write
DMA0
Write
CPU
CPU
CPU
CPU
CPU
CPU
CPU
CPU
CH0
CH1
*
*
*
*
*
*
*
*
Transfer
completed
Note:
*
The bus is always released. When the CPU requests the bus mastership, the CPU acquires the bus mastership.
Hardware DMA
transfer request 0
(input)
Acknowledge 0
(output)
Hardware DMA
transfer request 1
(input)
Acknowledge 1
(output)
DMA1
Read
DMA1
Read
DMA0
Read
DMA1
Read
DMA1
Write
DMA1
Write
DMA1
Write
DMA0
Write
CPU
CPU
CPU
CPU
CPU
CPU
CPU
CPU
CPU
CPU
· Software DMA transfer request (CH1)
· DMA transfer count setting: 3 times
High-priority DMA cycle
CH0
CH1
*
*
*
*
*
*
*
Transfer
completed
Note:
*
The bus is always released. When the CPU requests the bus mastership, the CPU acquires the bus mastership.
Hardware DMA
transfer request 0
(input)
Acknowledge 0
(output)
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