TENNOVATIVE ENGINEERING SOLUTIONS

Project Good Karma

GoPro Karma Information

REVERSE ENGINEERING
DATA DUMP (WIP)

This page hosts information regarding the various circuits that make up the GoPro Karma Mainboard. The data included on this page is theoretical in nature and should be regarded as such. This information has been extrapolated from datasheets and application notes provided by the chipset manufacturers. The information provided here is based on 20+ years of experience of high-speed digital and power systems design.

This is information continually being updated as discoveries are made, hence the WIP (Work In Progress).

Battery Information

BATTERY INTERFACE CONNECTORS

SAMTEC SERIES

0.050″ EXTreme LPHPower 30Amp Signal/Power Combo Strip

MAINBOARD SIDE

LPHT-04-16-L-RT1-GP

BATTERY SIDE

LPHS-04-16-L-RT2-GP

Battery PCB TOP

Battery PCB BOTTOM

Circuit Description

Li-Ion Battery Pack Manager

Battery Pack Manager
Texas Instruments BQ40Z50 – VQFN32
Li-Ion Battery Pack Manager

The Go Pro Karma battery utilizes a TI BQ40Z50 pack manager. The pack manager offers these functions:

  • Fully Integrated 1-Series, 2-Series, 3-Series, and 4-Series Li-Ion Battery Management and Protection
  • Next-Gen Impedance Track
    • Accurately Measures Available Charge
  • High Side N-CH Protection FET Drive
  • Integrated Cell Balancing While Charging or At Rest
  • Programmable Protection Features
    • Voltage
    • Current
    • Temperature
    • Charge Timeout
    • CHG/DSG FETs
    • AFE
  • Integrated SMBus v1.1 Interface
  • Advanced Charging Algorithms
    • JEITA
    • Enhanced Charging
    • Adaptive Charging
    • Cell Balancing
  • Integrated Fuel Gauge Display Support
    • Up to 5 LED Fuel Gauge
    • Low Power Operation with Push Button Support
  • Supports TURBO BOOST Mode
  • Supports Battery Trip Point
  • Supports SHA-1 Authentication
  • Diagnostic Lifetime Data Monitor and Black Box Recorder

Temperature Monitoring

The pack manager also supports up to four thermistor connections for monitoring cell temperatures. The Karma battery only uses two of the four potential thermistor inputs.

Charge and Discharge Current Monitoring

There appears to be 3 x 0.002 ohm current sense resistors in a parallel configuration. This seems to fall outside of the nominal range expected by the pack manager. According to the datasheet, the pack manager uses the SRP and SRN inputs to measure and calculate the battery charge and discharge current using a 0.001 to 0.003 ohm typ. sense resistor. The calculated resistance for the sense resistors in the Karma battery is 0.0006 ohms.

Over Voltage Protection

Texas Instruments BQ2947 – WSON(8)
Overvoltage Protection for 2-Series to 4-Series Cell Li-Ion Batteries with External Delay Capacitor.


The Go Pro Karma battery pack employs a TI BQ2947 (Case Marking 705). This device monitors each cell independently for an overvoltage condition. In the event that a cell overvoltage condition occurs, the BQ2947 output is activated which energizes the heater path on the battery fuses (SFK 30A K45 A) which should blow the 30A main battery fuses.

Battery Fuses

Dexerials SFK 30A K45 A
Rated Current = 30A
Dimension = 9.5 x 5.0 x 2.0mm
Fuse Resistance = 1.3m-ohm
Operating Voltage = 10.5 – 23.5V
Heater Resistance = 4.8 – 8.0 ohm

Is a one-time protective device that permanently blows when the rated current or overheat condition is exceeded. The fuse contains an integrated heater to provide a means to deliberately accelerate fuse failure.

Microcontroller

Battery Pack Microcontroller
Texas Instruments MSP430G2230- SOIC8
16MHz MCU with 4KB Flash, 256B SRAM, SPI/I2C, Timer

The GoPro Karma battery employs a TI MSP430G2230 microcontroller. The microcontroller is operating as the SMBus master. As the master it is responsible for monitoring battery parameters and performance and relaying that data out to either the GoPro Battery Charger Supply or the GoPro Karma Drone. The microcontroller has an integrated timer which is responsible for generating the Alive pulse. The Alive pulse, also known as a heartbeat, is used to provide a indication to an attached device that the battery is there and that the system is operational.

Li-Ion Cell Information

Pack Rating = 14.8V 5.1Ah 75.4Wh
Single Cell Rating = 3.7V 5.1Ah 18.85Wh
Cells per Pack = 4

GoPro Karma

Mainboard Connectors

The mainboard connectors are broken up into functions. They comprise primarily of several FFC latch type connections. Connections in red are of little significance for repair, whereas connections in green are required for resolution of the pairing issue and WMM update processes. Blue connection is mainly used for system level troubleshooting.

RED
  • BAT – Battery Interface Connections
    • 12 Pin FFC – Hirose
    • Provides SMBus data and status to STM microcontroller.
  • LAB – Left Arm Board
    • 8 Pin FFC – Hirose
    • Provides deployment status for left arms.
  • WIFI – WiFi Interface
    • 12 Pin FFC – Hirose
    • Provides WIFI transceiver interface to DMSoC for video and control streams to and from controller.
  • GIMBAL – Gimbal Interface
    • 31 Pin FFC – Hirose
    • Provides USB Type C interface to gimbal for power, control, and HDMI video streams to DMSoC.
GREEN
  • RAB – Right Arm Board
    • 14 Pin FFC – Hirose
    • Provides deployment status for right arms.
    • Provided interface for microSD card slot to DMSoC for firmware load. (Not always populated.)
  • DMSoC – Digital Media System-on-Chip Debug Interface
    • 3 Pin – Hirose DF13
    • Provides debug interface for receiving and transmitting data.
BLUE
  • STM – STM Debug Interface
    • 3 Pin – Hirose DF13
    • Provides debug interface for monitoring STM microcontroller and all of its peripherals.

Battery Interface

This board is simple in nature. Only purpose is to provide an interface between the battery pack and the mainboard for power. Entirely passive in nature with only discrete components present with minimal connectivity.

FFC 12-PIN PINOUT

Molex 505278-1270

  1. GND
  2. GND
  3. GND
  4. VBAT
  5. VBAT
  6. VBAT
  7. VBAT
  8. SMB SDA
  9. SMB SCL
  10. BAT_PRES#
  11. BAT_OK
  12. BAT_ALIVE

BAT_PRES# is at logic high until drone is powered on.
BAT_OK is at logic low until drone is powered on.
BAT_ALIVE is pulsed every 250mS until drone is powered on.

Mainboard Top

YELLOW
RED
ORANGE
BLUE
VIOLET
GREEN

Mainboard Bottom

BLUE
ORANGE
CYAN
GREEN
VIOLET
  • Motion Processing Unit
    InvenSense MPU-6000
    Accelerometer, Gyroscope, 6 Axis Sensor I2C, SPI Output

PMIC Circuit

The PMIC is the primary power source for all digital circuitry. 3.3V and 1.8V are the most commonly used supplies on the mainboard. 1.35V the core supply for the DMSoC. 3.5V is overage for higher current non-shared 3.3V logic. Suspect this is the source for the 3.3V LDOs found on the prop motor controllers. Besides supplying multiple voltages, the PMIC also has a programmable power-up sequence controller. Typically there is a delayed start on 1.8V supplies as 1.8V is commonly used on DDR memory / DRAM. The DRAM controller should be powered up prior for DRAM initialization.

DMSoC Section

The DMSoC Section is home to several of the critical system components for the Karma drone.

The DMSoC is the primary system-on-chip responsible for video processing, WiFi communications, USB interfaces, as well as several other critical system interfaces. The DMSoC interfaces directly to the DRAM, NAND, and HDMI receiver.

DMSoC Pin Mapping

PROP MOTOR CONTROL & DRIVER CIRCUITS

The prop motor control and driver circuits are comprised of:

  • TI TPS 73533DRVR
    • 3.3V 500mA LDO supply
  • International Rectifier MCK099 iMOTION Motor Control IC
    • High performance sensor-less OTP memory based motion control ASIC
  • International Rectifier S2301 High And Low Side Driver IC
    • 3 total per prop motor, one for each motor phase.

This exact circuit is replicated four times on the main board for the Front Left, Front Right, Rear Left, and Rear Right Prop Motors.

GPS/GNSS MODULE TRANSCEIVER