BLUE-PILL-HUB

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P1050682-cropped-720px.jpg

BLUE-PILL-HUB - STM32F1 Board with I2C Hub

  • Socket for Blue Pill Board
    • STM32F1
  • I2C Multiplexer
    • 4 I2C interfaces
    • Interrupt to Blue Pill Board
    • Separate voltage selection for each I2C bus (3.3V or 5V)
  • GVS (Ground, Voltage, Signal) lines for all I/O Lines
    • Power, ground and signal distribution for each signal
  • SPI Connector
    • 6 pin Arduino pinout
  • FTDI connector
    • Standard 6-pins
    • 1:1 cable connections to external FTDI
    • Jumper Selectable 5V or 3.3V from FTDI
      • Must be set to match the power select jumpers on the external FTDI card
      • Jumper can be left open to not route any power from the FTDI
  • 5V Power input
    • On-board 3.3V regulator
      • Up to 1A current capability
      • I/O power separate from 3.3V Power out of Blue Pill Board
    • 5V Power distribution for I/O connections which need 5V power
      • Most Blue Pill board pins are 5V tolerant
  • Reset switch

Blue Pill Board

800px-Bluepill pinout.png

Blue Pill Board Modifications

  • Added USR0 switch to board for programming

BluePillSwitch.jpg

Connectors

GVS pins

  • There are GVS pins for all of the I/O lines on the Blue Pull
  • Note the silkscreen for the signals is adjacent to the GND pin of the port
    • The signal is the third pin (towards the center of the card)

5V Power

  • 2.5mm 5V "wall wart" jack

J4 - External 5V

  • 5mm terminal block

J7 - STM32 I2C interface

  • Connected directly to the I2C pins of the STM32
    • No interrupt line
  1. SCL
  2. SDA
  3. VCC (3.3V)
  4. GND

P1 - 5V Power

  • Provides Power for external 5V devices
    • 8 pairs of Power/ground
    • Make sure 5V devices only connect to 5V tolerant pins

P2 - Battery Connection

  • Power for the real-time clock in the STM32
  • GND
  • VBAT

P3 - FTDI

  • Connects directly to the FTDI pins
  • GND, Tx, Rx supported
  • Experimental support for reset on RTS (pin 1)
    • Capacitor coupled to momentarily pull reset down when the sketch download starts
  1. GND
  2. N/C
  3. VCC (3.3V)
  4. STM_RX (PA10)
  5. STM_TX (PA9)
  6. RTS (reset the card with capacitor - doesn't work)

P4 - I2C Port 0

  1. INT (PB8)
  2. SCL (PB6)
  3. SDA (PB7)
  4. VCC - Connects to H3 center pin
  5. GND

P5 - I2C Port 1

  1. INT
  2. SCL
  3. SDA
  4. VCC - Connects to H4 center pin
  5. GND

P6 - I2C Port 3

  1. INT
  2. SCL
  3. SDA
  4. VCC - Connects to H5 center pin
  5. GND

P7 - I2C Port 2

  1. INT
  2. SCL
  3. SDA
  4. VCC - Connects to H6 center pin
  5. GND

P8 - SPI bus

  • Same pinout as the Arduino SPI
  • 2x3 Header
  1. MISO
  2. VCC
  3. SCK
  4. MOSI
  5. RESET
  6. GND

Headers

  • Silkscreen ref des is near pin 1 of any header
  • Header pin 1 also has a square pad

H1 - Use 3.3V Regulator

  • Install to use the on-board 3.3V regulator (normally installed)
    • Requires external source of 5V to power the regulator

H2 - Use DC Jack

  • Installed = Use 5V from 5V Power jack or J4 terminal block
    • User should not connect power into the card on both jacks at the same time

H3 - I2C Port 0 - Power Select Jumper

  • Install shunt from 3.3V to Center pin to supply 3.3V Power to the I2C
  • Install shunt from 5V to Center pin to supply 5V Power to the I2C
  • Remove shunt from both positions to allow external interface to power I2C port

H4 - I2C Port 1 - Power Select Jumper

  • Install shunt from 3.3V to Center pin to supply 3.3V Power to the I2C
  • Install shunt from 5V to Center pin to supply 5V Power to the I2C
  • Remove shunt from both positions to allow external interface to power I2C port

H5 - I2C Port 3 - Power Select Jumper

  • Install shunt from 3.3V to Center pin to supply 3.3V Power to the I2C
  • Install shunt from 5V to Center pin to supply 5V Power to the I2C
  • Remove shunt from both positions to allow external interface to power I2C port

H6 - I2C Port 2 - Power Select Jumper

  • Install shunt from 3.3V to Center pin to supply 3.3V Power to the I2C
  • Install shunt from 5V to Center pin to supply 5V Power to the I2C
  • Remove shunt from both positions to allow external interface to power I2C port

H7 - Use 3.3V from Blue Pill to Power the card

  • Normally not installed
  • For very low external power usage it could be installed
  • Blue Pill output current is around 100 mA???

H8 - FTDI Power Select Jumper

  • Install shunt between 5V and center pin to power the card from the FTDI 5V
  • Install shunt between 3.3V and center pin to power the card from the FTDI 3.3V
    • The FTDI 3.3V supplies very low current - not sufficent to run much hardware

Rev 1 Checkout

  • FTDI Rx/Tx backwards
    • Swap Rx/Tx in cable
  • Downloaded STM32 Blink sketch and it ran
  • FTDI cap reset doesn't work
    • Still need to press reset to download
    • On-board reset switch works
  • I2C hub works
    • Only checked port 0 so far
    • Port 3 works with ODAS Tester

Blue Pill Hub Assembly Sheet

Blue_Pill_Assembly_Sheet