MC68HC708XL36 FREESCALE [Freescale Semiconductor, Inc], MC68HC708XL36 Datasheet - Page 130

• Manufacturer Part Number: MC68HC708XL36
• Description: HCMOS Microcontroller Unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

DMA
Low-Power Modes
Wait Mode
Stop Mode
MC68HC708XL36
130
The WAIT and STOP instructions put the MCU in low-power-consump-
tion standby modes.
If enabled by the DMAWE bit in the DMA status and control register, the
DMA remains active in wait mode. The DMA can transfer data to and
from peripherals while the MCU remains in wait mode.
If the WAIT instruction occurs during a DMA transfer while DMAWE is
set, the DMA transfer continues to completion. If the DMAWE bit is clear,
a WAIT instruction suspends the current DMA transfer. If the DMA
priority bit (DMAP) is set, the suspended transfer resumes when the
MCU exits wait mode.
The DMA is inactive during stop mode. A STOP instruction suspends
any DMA transfer in progress. If an external interrupt brings the MCU out
of stop mode and the DMA priority bit (DMAP) is set, the suspended
DMA transfer resumes. If a reset brings the MCU out of stop mode, the
transfer is aborted.
Entering stop mode when a DMA channel is enabled may fail to clear the
the interrupt mask (I bit) in the condition code register. To make sure the
I bit is cleared when entering stop mode:
•
•
Freescale Semiconductor, Inc.
For More Information On This Product,
Before executing the STOP instruction, wait until any current DMA
transfer is complete. Then disable DMA transfers by clearing bits
TEC[2:0] in DMA control register 1.
Or,
Execute the clear-interrupt-mask instruction (CLI) before entering
stop mode.
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DMA
MOTOROLA
20-dma_b