User's Manual l MBa8Xx UM 0100 l © 2020, TQ-Systems GmbH
Page 35
Mini PCIe (continued)
By default, the Mini PCIe reference clock for the i.MX 8X processor and the Mini PCIe card is generated by a clock generator
(Renesas 9FGV0241). This implementation is based on the experience that the CPU internal PCIe reference clock usually does not
meet the JEDEC jitter specifications.
For test purposes the reference clock of the TQMa8Xx4 can also be used directly.
The required assembly options are described in the following table.
Table 38:
Assembly option Mini PCIe reference clock
Mode
R318
R319
C23
C24
R157
R158
R471
R472
Remark
Discrete clock generator
NP
NP
NP
NP
0 Ω
0 Ω
0 Ω
0 Ω
Default
Clock from TQMa8Xx4
49.9 Ω
49.9 Ω
100 nF
100 nF
NP
NP
NP
NP
–
Attention: PCIe clock generator on TQMa8Xx4 present
When using a TQMa8Xx4 with assembled PCIe clock generator, the above assembly option
(TQMa8Xx4 as reference clock) is compulsory to be implemented. This prevents the two clock
generators from the TQMa8Xx4 and the MBa8Xx driving against each other.
The separate clock generator 9FGV0241 offers the possibility to vary the spread spectrum at the clock outputs.
By default the spread option is disabled.
Table 39:
Assembly option Spread Spectrum of the Mini PCIe reference clock
Spread-Option
R1
R2
Remark
Spread off
NP
1 kΩ
Default
Spread = –0.25 %
NP
NP
–
Spread = –0.5 %
1 kΩ
NP
–
By default the I2C1 bus is not connected to the Mini PCIe clock generator.
This can be done, as shown in the following table, by assembling two resistors.
Table 40:
Assembly option I2C1 bus at Mini PCIe clock generator
I2C1 bus
R155
R156
Remark
Not connected
NP
NP
Default
Connected
0 Ω
0 Ω
–
3.8.9
SIM card
A SIM card holder is available on the MBa8Xx for the use of a SIM card (X25), which is directly connected to the Mini PCIe
interface.
Media type:
GSM (SIM cards with form factor 2FF/UICC)
Interface TQMa8Xx:
–
Compatibility:
Specification of the Subscriber Identity Module - Mobile Equipment Interface (GSM 11.11)
Transfer rate:
–
ESD protection:
Not available on the MBa8Xx
