Renesas M16C/6NK Información técnica Pagina 128

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Rev.2.10 Apr 14, 2006 page 104 of 378
REJ09B0124-0210
M16C/6N Group (M16C/6NK, M16C/6NM) 12. DMAC
Item Specification
No. of channels 2 (cycle steal method)
Transfer memory space From given address in the 1-Mbyte space to a fixed address
From a fixed address to given address in the 1-Mbyte space
From a fixed address to a fixed address
Maximum no. of bytes transferred 128 Kbytes (with 16-bit transfer) or 64 Kbytes (with 8-bit transfer)
DMA request sources
(1) (2)
________ ________
Falling edge of INT0 or INT1
________ ________
Both edge of INT0 or INT1
Timers A0 to A4 interrupt requests
Timers B0 to B5 interrupt requests
UART0 transmit, UART0 receive interrupt requests
UART1 transmit, UART1 receive interrupt requests
UART2 transmit, UART2 receive interrupt requests
SI/O3, SI/O4 interrupt requests
A/D conversion interrupt requests
Software triggers
Channel priority DMA0 > DMA1 (DMA0 takes precedence)
Transfer unit 8 bits or 16 bits
Transfer address direction forward or fixed (The source and destination addresses cannot both be
in the forward direction.)
Transfer mode Single transfer Transfer is completed when the DMAi transfer counter underflows
after reaching the terminal count.
Repeat transfer When the DMAi transfer counter underflows, it is reloaded with the value
of the DMAi transfer counter reload register and a DMA transfer is
continued with it.
DMA interrupt request When the DMAi transfer counter underflowed
generation timing
DMA start up Data transfer is initiated each time a DMA request is generated when the
The DMAE bit in the DMAiCON register = 1 (enabled).
DMA shutdown Single transfer When the DMAE bit is set to 0 (disabled)
After the DMAi transfer counter underflows
Repeat transfer When the DMAE bit is set to 0 (disabled)
Reload timing for forward When a data transfer is started after setting the DMAE bit to 1 (enabled),
address pointer and transfer the forward address pointer is reloaded with the value of the SARi or the
counter DARi pointer whichever is specified to be in the forward direction and the
DMAi transfer counter is reloaded with the value of the DMAi transfer
counter reload register.
DMA transfer cycles Minimum 3 cycles between SFR and internal RAM
Table 12.1 DMAC Specifications
i = 0, 1
NOTES:
1. DMA transfer is not effective to any interrupt. DMA transfer is affected neither by the I flag nor by the
interrupt control register.
2. The selectable DMA request sources differ with each channel.
3. Make sure that no DMAC-related registers (addresses 0020h to 003Fh) are accessed by the DMAC.
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