Control and Expansion Interfaces

Power Switch Interface

Overview

The Power Switch Interface is a single connector that enables GPIO power-down control of the OEM modem.

Electrical Connections

All signal directions are relative to the OEM modem. Refer to the top connector locations figure for the physical location of the connector.

Power Switch schematic connections.

Power Switch Electrical Pinout

Pin Number	I/O	Pin Name	Notes
1	P	VDD_3V3	+3.3 V out when unit is powered up
2	I	Power Switch	Short to GND to power down the unit; leave open for normal operation
3	P	GND	Board ground

Hardware Components

The Power Switch Interface uses a Molex PicoBlade connector, P/N 0510210300, or equivalent.

Power Switch Interface user-side Molex connector.

Power Switch Interface Components and Part Numbers

Part Number	Manufacturer	Description
0510210300	Molex	PicoBlade 3-position connector receptacle, 1.25 mm pitch
0500798000	Molex	PicoBlade 26–28 AWG sockets
2002181900	Molex	PicoBlade hand crimp tool
2149202211	Molex	Pre-crimped PicoBlade lead, 75 mm length

Mating Cable Notes

Attach or detach the interface only while power is disconnected from the OEM modem.

MPU Expansion Interface

Overview

The MPU Expansion Interface is a single connector for communicating with the modem MPU through +5 V logic-level SPI, I2C, and GPIO peripherals. All pins on this expansion header are level-translated from the internal logic voltage to +5 V for robustness.

Electrical Connections

All signal directions are relative to the OEM modem. Refer to the bottom connector locations figure for the physical location of the connector.

MPU Expansion Interface schematic connections.

MPU Expansion Interface Electrical Pinout

Pin Number	I/O	Pin Name	Notes
1	P	VSYS_5V	+5 V out when unit is powered up
2	O	ECSPI1_SCLK_5V	SPI serial clock
3	I	ECSPI1_MISO_5V	SPI Master In Slave Out
4	O	ECSPI1_MOSI_5V	SPI Master Out Slave In
5	O	ECSPI1_SS0_5V	SPI slave select
6	O	I2C3_SCL_5V	I2C clock, maximum 400 kHz
7	I/O	I2C3_SDA_5V	I2C data
8	O	EXP0_OUT_5V	General-purpose digital output
9	I	EXP1_IN_5V	General-purpose digital input
10	P	GND	Board ground
11	P	VDD_3V3	+3.3 V out when unit is powered up
12	P	GND	Board ground

Fixed signal directions

Because of the internal 5 V level translators, the signal directions shown above are fixed and cannot be modified.

Hardware Components

The MPU Expansion Interface uses a Molex PicoBlade connector, P/N 0510211200, or equivalent.

MPU Expansion Interface user-side Molex connector.

MPU Expansion Interface Components and Part Numbers

Part Number	Manufacturer	Description
0510211200	Molex	PicoBlade 12-position connector receptacle, 1.25 mm pitch
0500798000	Molex	PicoBlade 26–28 AWG sockets
2002181900	Molex	PicoBlade hand crimp tool
2149202211	Molex	Pre-crimped PicoBlade lead, 75 mm length

Mating Cable Notes

Attach or detach the interface only while power is disconnected from the OEM modem.

Wakeup MCU Expansion Interface

Overview

The Wakeup MCU Expansion Interface is a single connector for communicating with the wakeup MCU through +1.8 V logic-level analog and digital peripherals.

Shared connector

This interface uses the same physical connector as the MPU Expansion Interface, but it does not use the same pinout. Contact info@popotomodem.com if your application requires this interface.