The AutoQuad M4 autonomous flight controller is a wonderful little piece of electronics.
Much information on it is found in the AutoQuad Documentation. However, it is closed source and the electronic scheme not available, but in daily life one often needs information only accessible with a basic knowledge on the components and electric scheme. I hence started to get more insight, and share my findings here.
The info provided here refers to the M4 v2 (rev6).
The page will start slowly, but more info will be added and it will hence grow with time.
Electronic Components
The identification of the parts did took more efforts than I’ve anticipated. The exact USB esd protection chip and motor FETs resisted my efforts, but their types were fortunately provided in the AutoQuad Forum, and all pieces of the puzzle fell in place. That’s the result:
processing
micro processor: STM32 F405RG @ 168 MHz (product page) (datasheet) (reference manual) (programming manual)
EEPROM: CAT25512, 512 kB, SPI (product page) (datasheet)
sensors
gyro and accelerometer: MPU6000, SPI (product page) (datasheet)
magnetometer: HMC5983 (product page) (datasheet)
barometer: MS5611-01BA03 (product page) (datasheet)
GPS: MAX-M8Q (product page) (datasheet) (manual) (protocol) (see also this post!)
interfaces
USB esd protection: NUF2221W1 (datasheet)
CAN bus transceiver: SN65HVD232D (product page) (datasheet)
power path
buck boost converter: TPS63031 (product page) (datasheet)
lipo battery charger & power management: BQ24075-Q1 (product page) (datasheet)
on/off controller: MAX16054 (product page) (datasheet)
motor driver stage
MOSFETs: PMV31XN (product page) (datasheet)
Port Assignments
The pins on the F405 are used as follows.
MPU6000
spi3, SCLK = pin B3, MISO = pin B4, MOSI = pin B5, CS = pin C14, EXTI = pin C3
HMC5983
spi3, SCLK = pin B3, MISO = pin B4, MOSI = pin B5, CS = pin C13, EXTI = pin A2
MS5611
spi3, SCLK = pin B3, MISO = pin B4, MOSI = pin B5, CS = pin A8,
GPS
uart4, RX = pin A1, TX = pin A0
CYRF9636
spi1, SCLK = pin A5, MISO = pin A6, MOSI = pin A7, CS = pin B11, IRQ = pin B14
EEPROM
spi3, SCLK = pin B3, MISO = pin B4, MOSI = pin B5, CS = pin C15,