DragonBoard 410c - How to Works the Low Speed Expansion

This tutorial is about the Low Speed Expansion on DragonBoard 410c. The Inputs and Outputs (I/O) of Low Speed Expansion on DragonBoard 410c are:

GPIO (General Purpose Input/Output);
MPP (Multi Purpose Pin);
SPI (Serial Peripheral Interface);
I2C (Inter-Integrated Circuit);
UART (Universal Asynchronous Receiver / Transmitter);
PCM (Pulse Code Modulation).

Step 1: Low Speed Expansion - Schematic

Download DragonBoard 410c Schematic:

https://developer.qualcomm.com/qfile/34580/lm25-p0436-1_a_db410c_schematic.pdf

Step 2: Pin Information - Ground

Step 3: Pin Information - Power Supplies

The DragonBoard 410c supports:

+1.8V:

Driven by two PMIC LDOs, LDO15 and LDO16, each can provide 55mA. The PM8916 allows connecting the two LDOs in parallel to provide 110mA on a 1.8V.

+5V:

Driven by the 4A 5.0V buck switcher (U13). This buck switcher powers both USB limit current devices (each at 1.18A max). The remaining capacity provides a max current of 1.64A to the Low Speed Expansion Connector, for a total of 8.2W.

SYS_DCIN:

Can serves as the board’s main power source or can receive power from the board.

Step 4: Pin Information - GPIO

The 96Boards specifications calls for 12 GPIO lines to be implemented on the Low Speed Expansion Connector. Some of these GPIOs may support alternate functions for DSI/CSI control. 11 GPIOs are routed to the APQ8016 SoC and one GPIO is connected to the on-board PMIC.

GPIO A (Pin 23)

Connects to GPIO_36 of APQ8016 SoC, can serves as AQP_INT supporting the 96Boards requirements to create a wake-up event for the SoC. It is a 1.8V signal.

GPIO B (Pin 24)

Connects to GPIO_12 of APQ8016 SoC. It is a 1.8V signal.

GPIO C (Pin 25)

Connects to GPIO_13 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be an IRQ line.

GPIO D (Pin 26)

Connects to GPIO_69 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be an IRQ line.

GPIO E (Pin 27)

Connects to GPIO_115 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be an IRQ line;

GPIO F (Pin 28)

Connects to MPP_4 of PM8916 PMIC. It is a 1.8V signal. Can be configured to be the DSI backlight control.

GPIO G (Pin 29)

Connects to GPIO_24 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be DSI VSYNC signal.

GPIO H (Pin 30)

Connects to GPIO_25 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be a DSI_RST signal.

GPIO I (Pin 31)

Connects to GPIO_35 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be a CSI0_RST signal.

GPIO J (Pin 32)

Connects to GPIO_34 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be a CSI0_PWDN signal.

GPIO K (Pin 33)

Connects to GPIO_28 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be a CSI1_RST signal.

GPIO L (Pin 34)

Connects to GPIO_33 of APQ8016 SoC. It is a 1.8V signal. Can be configured to be a CSI1_PWDN signal.

Step 5: Pin Information - I2C

The DragonBoard 410c implements I2C0 and I2C1 that connects directly to the APQ8016SoC;

A 2K resistor is provided as pull-up for each of the I2C lines per the I2C specifications, these pull-ups are connected to the 1.8V voltage rail.

Step 6: Pin Information - SPI

The DragonBoard 410c implements a full SPI master with 4 wires, CLK, CS, MOSI and MISO all connect directly to the APQ8016 SoC;
These signals are driven at 1.8V.