Data Sheet

ISM14585-L35 Specification
DOC-DS-14585-201807-3.0
Confidential Inventek Systems
Page 24
9.4.2.5 POWER-ON RESET CONSIDERATIONS
If any of the POR sources is asserted then the POR timer starts to count. When a POR
source is released before the timer has expired, POR timer will reset to 0. If a second
source is asserted while the first is already asserted and the first is released after that
point, POR will occur; assuming that the total time of both sources kept asserted is
larger or equal than the POR_TIME.
The POR_PIN_REG[PIN_SELECT] field cannot survive any Reset (POR, HW, SW) and
as such the user must take special care on setting up the GPIO POR source right after
a reset. This also applies for the POR_TIMER_REG[POR_TIME] field after a Power-On
Reset.
The user must also take into account that if a GPIO is used as POR source, the
dynamic current of the system increases due to the dynamic current consumed by the
RC32k oscillator. This increase is calculated to be 100nA to 120nA and it is also present
during sleep time period. POR from Reset pin does not add this dynamic current
consumption.
9.5 DMA Controller
The DMA controller has 4 Direct Memory Access (DMA) channels for fast data transfers
from/to SPI, UART, I2C, PDM and PCM to/from any on-chip RAM. The DMA controller
off-loads the ARM interrupt rate if an interrupts is given after a number of transfers.
More peripherals DMA requests are multiplexed on the 4 available channels, to
increase utilization of the DMA. The block diagram of the DMA controller is depicted in
Figure 7.
Features:
• 4 channels with optional peripheral trigger
• Full 32 bit source and destination pointers.
• Flexible interrupt generation.
• Programmable length.
• Flexible peripheral request per channel.
• Option to initialize memory.
• Programmable Edge-Sensitive request support(suggested for UART and I2C
service)