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User's Manual l TQMa7x UM 0203 l © 2022, TQ-Systems GmbH
Page 17
Attention: Malfunction or destruction
Some eMMC have a too high drive-strength. This can lead to poor signal integrity and a life time
reduction of the CPU. When using an own bootloader or operating system it is essential to implement
the SET_DSR routine, which is part of the
since revision 01xx.
Since not all types of eMMC allow a driver strength adaptation, eMMC signals were attenuated by
serial terminations from TQMa7x revision 02xx onwards. Therefore, from TQMa7x revision 02xx
onwards, the SET_DSR routine may no longer be used. The additional signal damping might cause
malfunctions.
The following eMMC modes are supported at the USDHC3 port of the i.MX7:
Table 13:
USDHC3 eMMC modes
eMMC mode
1 bit
4 bit
8 bit
Fast boot
Remark
Normal
Speed
Yes
Yes
Yes
No (8)
Not tested
High Speed
Yes
Yes
Yes
No (8)
–
HS200
n.a. (9)
Yes
Yes
No (8)
–
HS400
n.a. (9)
n.a. (9)
Yes
No (8)
Default in
Attention: Malfunction or destruction
An implementation of the SET_DSR routine from the BSP Rev.0104 must no longer be carried out for
modules from REV.0200 onwards, as this can lead to malfunctions due to additional signal attenuation.
3.2.2.3
QSPI NOR flash
A 64 Mbyte Micron QSPI NOR flash type MT25QL512ABB8E12-0SIT is available as assembly option. It can e.g., serve as boot
device or as recovery device.
The following block diagram shows how the QSPI NOR flash is connected to the i.MX7.
i.MX7
SPI NOR flash
QSPIA_SCLK
QSPIA_DATA[3:0]
QSPIA_SS0#
3.3 V
QSPIA_RESET#
Connector
QSPIA_SCLK
QSPIA_DATA[3:0]
QSPIA_SS0#
QSPIA_RESET#
QSPIA_SS1#
QSPIA_SS1#
Reset logic
RESET_OUT#
0
Ω
NP
Figure 5:
Block diagram QSPI NOR flash interface
8:
Not supported by software.
9:
Not specified by JEDEC.