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Carrier Board Design Guide for SOM-9X35 Module
62
Note:
An N Channel MOS FET should be a fast-switching type, the Vgs(th) gate-source threshold voltage should be less
than 1.65V. In order to prevent power leakage, the PWM output signal should be set to Low when the system is
suspended.
PWM Level S
hi�
Very fast switching
1V8_VCC
3V3_VCC
1V8_VCC
3V3_VCC
PWM0_RPI
PWM_A
[5]
PWM1_RPI
[25]
PWM_C
[5]
R653
10K
C755
0.1uF
16V
X7R
R651
10K
Q66
BSS138BKS
60V
320mA
TRANSISTOR DUAL N CHANNEL
S1
1
G1
2
D2
3
S2
4
G2
5
D1
6
C753
0.1uF
16V
X7R
R654
4.7K_1%
R652
4.7K_1%
[25]
Figure 76: SOM-9X35 PWM level shift reference circuitry
4.12 I2C Interface
The SOM-9X35 module features three I2C interfaces.
4.12.1
I2C Signal Definition
The following table provides the definition of the I2C signals that are implemented in the M.2 slot.
Signal Name
Pin #
I/O
Pad Characteristics
Description
Voltage
Type
SDA2
J1.7
GPIO61
1.8V
I, PU
I2C2 SDA, default connect to front Camera and
MCU/IO extender
SCL2
J1.9
GPIO62
1.8V
I, PU
I2C2 SCL, default connect to front Camera and
MCU/IO extender
SCL1
J1.24
GPIO60
1.8V
I, PU
I2C1 SCL, default connect to Capacitive Touch
Panel and Rear camera
SDA1
J1.26
GPIO59
1.8V
I, PU
I2C1 SDA, default connect to Capacitive Touch
Panel and Rear camera
SDA0
J2.27
GPIO57
1.8V
I, PU
I2C0 SDA, default connect to G-sensor and DC/DC
SCL0
J2.29
GPIO58
1.8V
I, PU
I2C0 SCL, default connect to G-sensor and DC/DC
Table 37: SOM-9X35 I2C signal definition
4.12.2
I2C Design Notes
• The devices with the same slave address cannot use the same Bus.
•
All MT8365 I2C are 1.8V domain only, all the device I2C ports should be the same.
− Do not pull High the I2C Bus on the carrier board as it is already pulled High to 1.8V on SOM-9X35
module.
− The I2C SDA/SCL Bus is pulled High while the system is suspended, it is pulled Low when the
system is powered off.