Data Sheet

ISM14585-L35 Specification
DOC-DS-14585-201807-3.0
Confidential Inventek Systems
Page 28
requests DMA. If two or more channels have the same priority, an inherent priority
applies, (see register description).
With DREQ_MODE = 0, a DMA can be interrupted by a channel with a higher priority if
the DMA_IDLE bit is set. When DMA_INIT is set, however, the DMA channel currently
performing the transfer locks the bus and cannot be interrupted by any other channel,
until the transfer is completed, regardless if DMA_IDLE is set. The purpose of
DMA_INIT is to initialize a specific memory block with a certain value, fetched also from
memory, without any interruption from other active DMA channels that may request the
bus at the same time. Consequently, it should be used only for memory initialization,
while when the DMA transfers data to/ from peripherals, it should be set to '0'. Note that
AINC must be set to '0' and BINC to '1', when DMA_INIT is enabled.
It should be noted that memory initialization could also be performed without having the
DMA_INIT enabled and by simply setting AINC to '0' and BINC to '1', provided that the
source address memory value will not change during the transfer. However, it is not
guaranteed that the DMA transfer will not be interrupted by other channels of higher
priority, when these request access to the bus at the same time.
9.5.5 FREEZING DMA CHANNELS
Each channel of the DMA controller can be temporarily disabled by writing a 1 to freeze
all channels at SET_FREEZE_REG.
To enable the channels again, a 1 to bits at the RESET_FREEZE_REG must be written.
There is no hardware protection from erroneous programming of the DMA registers.
It is noted that the on-going Memory-to-Memory transfers (DREQ_MODE='0') cannot be
interrupted. Thus, in that case, the corresponding DMA channels will be frozen after any
on-going Memory-to memory transfer is completed.
9.6 I2C Interface
The I2C Interface is a programmable control bus that provides support for the
communications link between Integrated Circuits in a system. It is a simple two-wire bus
with a software-defined protocol for system control, which is used in temperature
sensors and voltage level translators to EEPROMs, general-purpose I/O, A/D and D/A
converters.
Features