A x e l H a r d w a r e M a n u a l
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5.6.2
USB Recovery
The USB Serial Downloader provides a means to download the
bootloader image to the chip over USB serial connection.
Please refer to the XELK Quick Start Guide for further details.
5.6.3
SD/MMC Recovery
MMC recovery is a valuable options that requires no special
hardware at all, apart a properly formatted MMC. The boot
sequence must include the SD/MMC option and a way to enable
it. When SD/MMC boot option is selected, bootrom looks for a
valid FSBL on SD/MMC, which in turn will load the 2nd stage
bootloader. Once the board is running after booting from SD,
reprogramming the flash memory is straightforward.
5.7
Multiplexing
Most of the i.MX 6 processor pins have multiple signal options.
These signal to pin and pin to signal options are selected by the
input output multiplexer called IOMUX. The IOMUX enables
flexible IO multiplexing and is also used to configure other pin
characteristics, such as voltage level, drive strength, and
hysteresis. Each IO pad has default and up to seven alternate
functions, which are software configurable.
Please refer to the following sections of the i.MX6 APRM for
further information pin assignment:
●
chapter 4 “External Signals and Pin Multiplexing”
●
section 4.1 “Pin assignments”
●
section 4.2 “Muxing options”
●
chapter 36 “IOMUX Controller (IOMUXC)”
5.8
RTC
An on-board Maxim Integrated DS3232 device provides a very
accurate, temperature-compensated real-time clock (RTC)
resource with:
●
Temperature-compensated crystal oscillator
●
Date, time and calendar
April, 2015
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