Flying Stone Tiny 01 revision G

Five years passed from the initial design of FST-01. Now, I have another revision "G", where "G" may stand for "Good" or "Green".

Update is required for two reasons:

  • The LDO regulator became discon.
  • KiCAD has been changed. Especially, the file format has been changed.

Components of FST-01

  • STM32F103TB
  • USB Terminator
  • LDO Regulator (3.3V)
  • 12MHz XTAL
  • LED
  • SWD Port of GND/SWDIO/SWDCLK
  • Extension port of VDD/GND/Port0/Port1
  • USB plug A
  • (Optional SPI Flash memory)

The change for FST-01G is LDO Regulator and SPI Flash memory.

STM32F103TB

MCU is one of Cortex-M3 based ARM by STMicroelectronics. It runs at 72MHz and has 128KB flash ROM and 20KB RAM.

No change from original FST-01.

USB Terminator

We use NUF2221W1 USB Upstream Terminator.

This is because it has the feature of electrostatic discharge protection It is also better for smaller footprint than two capacitors and two resistors.

No change for chip from original FST-01. The connection is improved.

LDO Regulator

This is the change from original FST-01.

We use LP2985-33DBVR for 3.3V Regulator (from 5V). Currency of 150mA is enough.

XTAL 12MHz

We use 12MHz XTAL.

This is because we can find smaller footprint XTAL for 12MHz (than 8MHz).

No change from original FST-01.

LED

We use a LED to show status.

No change from original FST-01.

SWD port

SWD port is to update MCU's flash ROM.

No change from original FST-01.

Extension port of VDD/GND/Port0/Port1

We decided to have two I/O pins. (One I/O pin is not enough even for minimalist.)

With two I/O pins, it can be:

  • TX and RX of serial communication
  • Drive and input of touch sensor
  • Controlling other MCU's SWD port

No change from original FST-01.

USB plug A

FST-01 usage is just to connect it into USB port, like USB thumb drive.

No change from original FST-01.

Note that this might be weak point; Attacker can put tiny malicious chip inside USB plug A plug.

SPI Flash memory

SPI Flash memory is optional. Original FST-01 has the chip.

CE and WEEE marking

For exporting to Europe, I put CE and WEEE marking on PCB.

It is your responsibility to conform those derectives.

Engineering prototype of FST-01G

Here is the prototype of FST-01G.

Prototype of FST-01G