HM-MIFIB Pinouts: LCD Screen SPI, Battery Contacts & EDL Pads

Because the HM-MIFIB incorporates an integrated display, battery management circuitry, and physical buttons, its hardware architecture is more sophisticated than standard USB dongles.

Battery Compartment & Test Point Layout

Removing the plastic back cover and battery reveals the inner chassis:

   ┌─────────────────────────────────────────────────────────┐
   │                                                         │
   │       ┌─────────────────────────────────────────┐       │
   │       │                                         │       │
   │       │          Battery Bay (3.7V)             │       │
   │       │                                         │       │
   │       │   [+]   [T]   [-]                       │       │
   │       │  VBAT  NTC   GND                        │       │
   │       │                                         │       │
   │       │               (o) (o) <── EDL Test Pads │       │
   │       │                                         │       │
   │       │    ┌──────────────────────────────┐     │       │
   │       │    │ Micro-SIM Slot               │     │       │
   │       │    └──────────────────────────────┘     │       │
   │       └─────────────────────────────────────────┘       │
   │                                                         │
   │   [TX] [RX] [GND] (1.8V UART under sticker)             │
   └─────────────────────────────────────────────────────────┘

1. Battery Pinout & Power Management

The battery connector features 3 gold leaf-spring contacts:

Pin	Label	Description
1	VBAT	Positive battery terminal (+3.7V nominal, 4.2V fully charged).
2	NTC / ID	Negative Temperature Coefficient 10kΩ thermistor to GND for temperature monitoring.
3	GND	Battery ground return.

PM8916 Power Management:

Charging is managed directly by the Qualcomm PM8916 PMIC via the kernel driver qpnp-charger.
Battery capacity, voltage, and discharge rates are tracked by the qpnp-bms (Battery Management Subsystem) gauge.

2. Color TFT LCD Display Connections

The onboard 1.44-inch color LCD display is driven by an ST7735S or ILI9163 controller connected over the Snapdragon 410’s high-speed SPI bus (BLSP):

Display Line	Connected SoC Pin	Description
MOSI (SDA)	BLSP1_SPI_MOSI (GPIO 0)	Serial data from SoC to display
SCK (SCL)	BLSP1_SPI_CLK (GPIO 1)	Serial clock
CS	BLSP1_SPI_CS_N (GPIO 2)	Chip select (Active Low)
D/C (A0)	GPIO 115	Data / Command register select
RESET	GPIO 114	Hardware display reset line
BACKLIGHT	PMIC LDO / GPIO 113	Display LED backlight brightness (PWM)

3. Entering Qualcomm EDL Mode (9008)

To recover a soft-bricked device:

Remove the battery completely from the device.
Connect a USB cable from your host PC to the device’s USB port (do not insert the battery yet).
Locate the two small round gold test pads labeled EDL (or unpopulated pads near the SIM slot).
Short the two pads together with metal tweezers.
While keeping the pads shorted, insert the battery or apply 5V USB power.
Hold for 2 seconds, then remove the short.

Confirm EDL mode on your PC:

lsusb | grep 05c6:9008
# Qualcomm, Inc. Gobi Wireless Modem (QDL mode)

4. Hardware UART Serial Console (1.8V)

Under the white regulatory sticker inside the battery bay, there are 3 miniature gold test pads for the serial console:

TX (1.8V): Connects to adapter RX.
RX (1.8V): Connects to adapter TX.
GND: Common Ground.
Baud Rate: 115200 (8N1).

5. Physical Button Mappings

Button	Hardware GPIO	Interrupt / Logic	Purpose
Power Key	PMIC `PWRKEY`	Active Low (Hold 3s)	Powers device on/off; short press toggles LCD backlight
WPS / Nav Key	GPIO 107	Active Low (Pull-up)	Custom user actions (toggle Wi-Fi, run scripts)

6. Hardware Mod: 5V USB Host Mode (VBUS Booster Mod)

While the Qualcomm Snapdragon 410 chipset supports USB OTG/Host mode in software, the HM-MIFIB board does not supply +5V power to the USB VBUS pin when running on battery.

To power external USB peripherals (keyboards, flash drives, wireless microphone dongles):

Connect an MH-CD42 step-up boost converter to step up the 3.7V battery voltage to 5.0V.
Route the 5V booster output to the USB connector’s VBUS pin.
Install an inline toggle power switch on the 5V boost line to avoid current collision when plugging in a USB wall charger.

Watch the full hardware soldering and assembly walkthrough by @glos-os:

Frequently Asked Questions — HM-MIFIB (MIFIB)

Does OpenStick Debian support the HM-MIFIB LCD screen and battery?

Yes. With lk2nd and the HM-MIFIB mainline device tree, Linux initializes both the 1.44-inch SPI color LCD display and the PM8916 battery fuel gauge.

👉 Ready to flash? Download the 1-Click OpenStick Debian Installer or browse Verified Store Links.