Blue Pill Adapter
NOTE: If you received a pre-assembled adapter then you can skip straight to Hardware Connection.
Directly connecting a "Blue Pill" to your floppy drive requires the following parts:
- STM32 "Blue Pill" board
- Adapter PCB
- 2.54mm-pitch Male Header Pins
- 4 x 0805 1k resistors (optional)
- 1 x 0805 1.5k resistor (optional)
The "Blue Pill" is available very cheaply from many Chinese Ebay sellers for less than £2 including postage. The best search term is "STM32F103C8T6 board", sorted by lowest price first, and look for a board identical to below.
UPDATE: Please be aware of fake STM32 chips flooding the Chinese market. You may be advised to use a local source for your Blue Pill: For example, in UK they can be purchased for £3-4, you can more easily question a local seller, and you have wasted much less time if your chip does turn out to be fake.
To source an adapter PCB, ask on the Facebook group page. Two types are available: One for 34-pin PC-compatible floppy drives, the other for 26-pin 3-inch Amstrad drives (used in CPC and Spectrum +3).
Before programming your Blue Pill board you should solder the supplied header pins as shown. Note that pins A9 and A10 point upwards so that they remain accessible after the adapter is assembled!
Please see the Firmware Programming page for further instructions.
After initial programming and adapter assembly, you can fully reprogram your Greaseweazle in future by connecting your serial programmer as below. Please note that you must connect to the 3.3v pin of your serial programmer in this case, as you are bypassing the Blue Pill's voltage regulator. Connecting to 5v power will kill your Greaseweazle! Most users will never need to connect in this way, and will use the simpler Firmware Update method.
First, solder the optional 0805 resistors to the adapter PCB. The four 1k resistors are highly recommended, and must be installed as a complete set of four, or else omitted entirely.
The 1.5k resistor is placed at the location marked USBPU and replaces R10 on the Blue Pill: You must remove R10 if you install this resistor. An easy method is to add solder to both sides of R10, and then alternate your soldering iron from side to side while applying light sideways pressure with tweezers until the resistor moves.
Next you must solder male header pins to the floppy and power headers (note that the power header is omitted on the Amstrad adapter). On the PC adapter board I recommend that you remove header pin 5, as in the picture below. This picture also illustrates use of a Berg power connector in place of 1x4 header pins.
Now solder the Blue Pill to the adapter board. You will already have soldered the supplied header pins to the Blue Pill, as described in the Firmware Programming section. Be careful to install your Blue Pill the right way round (the USB end is marked on the adapter), on the correct side of the adapter, and make sure R10 is removed first if you have installed USBPU on the adapter!
Note that the jumper at A9-A10 is simply to protect those pins from damage or shorting on metal surfaces. The jumper on the 4-pin header is the Firmware Update jumper and is moved one location sideways to enter Firmware Update mode: In normal operation it can be stored as illustrated, or omitted entirely.
Note also that the boot jumpers are both set to 0. This causes the Greaseweazle firmware to run at power on.