SmartDisk II: Hardware and installation

This page shows you what is on the board, how it is powered, how to connect it to your computer and what to check before you switch it on.

What you get

The SmartDisk II is one printed circuit board, 76.0 x 56.35 mm, with these parts:

Part	What it is
Microcontroller	STM32F411 “BlackPill” module, plugged on the board
Display	0.96 inch OLED module, 128 x 64 pixels, I2C (1.54 inch on the XL board)
Storage	microSD socket, push-push, with a card-detect contact
Keys	Four keys: UP, DOWN, ENTER, RET. On the XL board a rotary encoder replaces UP and DOWN
Reset	The NRST button of the BlackPill module
Buzzer	12 mm buzzer: key click, eject and insert sounds, failure sound
Drive connector	2 x 10 pin IDC header J2 (“APPLE_SDISKII”): the ribbon cable to the Apple II
USB	The USB connector of the BlackPill module. You use it to update the firmware (see page 04)

Revisions

Revision	What it is
8	Through-hole keys and connector, soldered by hand. Its gerber files are available on GitHub
9, SMD	The surface-mount keys and connector are placed by machine. The BlackPill, the OLED and the buzzer are fitted by hand
9, through-hole	Same board as revision 9 SMD, with a through-hole IDC header and through-hole keys, in the same positions as revision 8. It adds a 1N4148 diode D1 in parallel with D2
10, XL	The SmartDisk II XL: a 1.54 inch OLED and a rotary encoder in place of the UP and DOWN keys. See “The XL board”

The XL board needs its own firmware image (page 04).

Rev9 Not released yet on GitHub, What revision 9 changes against the earlier boards:

• Additional decoupling capacitor for SDCard and OLED,
• Additionnal resistor especially on PA0 (not 5V)
• Complete new routing
• New LDO to replace power rail on the board,
• New Buzzer decoupling to protect the blackpill

The XL board

Not released yet on github, The SmartDisk II XL (revision 10) is the revision 9 SMD board with two changes:

• A 1.54 inch OLED (SSD1309) instead of the 0.96 inch one.
• A rotary encoder with a push switch instead of the UP and DOWN keys.

How you use the encoder:

You do	The board sees
Turn clockwise, one click	DOWN (one entry down)
Turn counter-clockwise, one click	UP (one entry up)
Press the knob	ENTER

The ENTER and RET keys stay on the board and work as before: ENTER and the push of the encoder do the same thing. A turn of the knob replaces a held UP or DOWN key: to go down a long list, keep turning.

The rest of the board is the same as revision 9: the same connector, the same power jumpers, the same SD socket. Differences you may notice:

• There is no 0.96 inch OLED, no UP and DOWN key and no J5 debug header.
• The bypass pad BPR1 does not exist: R1 stays in the circuit.
• The UART header J4 has two pins: TX and GND.

The XL board runs the XL firmware, and the standard board runs the standard firmware. Check which file you download (page 04).

The connectors and solder pads, one by one

This section describes revision 9 (SMD and through-hole). The XL board has the same pads, except where “The XL board” above says otherwise.

Ref	What	What it does
J2	2 x 10 IDC header, “APPLE_SDISKII”	The cable to the Apple II (and, with an adapter, to the IIgs and Macintosh ports). The pin table is below
J1 “PWR”, silkscreen 5V	1 x 2 pin header	Pin 1: the 5 V pin of the BlackPill. Pin 2: the Apple 5 V after the fuse and the diode. A jumper here joins them. The solder pad JP1 makes the same connection
J7 “PWR”, silkscreen 3V	1 x 2 pin header	Pin 1: the 3.3 V rail of the board (OLED, SD socket, pull-ups, the 3.3 V pins of the BlackPill). Pin 2: the output of the board regulator U1. A jumper here feeds the rail from U1. The solder pad JP2 makes the same connection
J4 “UART”	3 pin header (2 pins on the XL board)	TX, RX, GND: the console log of the firmware, 460800 baud, 3.3 V levels
J5 “DEBUG”	4 pin header (not on the XL board)	Test points for a logic analyser
J6 “STLINK”	4 pin header	3V, SDIO (SWDIO), SCK (SWCLK), GND: the ST-Link programmer
BPF1	solder pad, open	Bypasses the fuse Fu1
BPR1, BPR2, BPR3	solder pads, open	Each bypasses one 330 ohm series resistor: R1 on WR_PROTECT (pin 20), R2 on the 3.5 inch select line (pin 7), R3 on SELECT (pin 12)
D2	SS54 diode	In series after the fuse
Fu1	resettable fuse, 750 mA	In series on the 5 V that comes from the drive connector

Notes:

• The pin headers J1, J4, J5, J6, J7 and the solder pads are not fitted by the assembly house: you solder them if you need them.
• All solder pads are open as designed. Leave the bypass pads open unless you know why you close them.
• The 330 ohm resistors protect the lines that the Apple II writes on (pins 7 and 12) and the one the board drives (pin 20).

The 20 pin header J2

Pin	Signal	Role
1, 3, 5	GND	ground
2	STEP0 (phase 0)	head stepper phase 0; SmartPort PH0; 3.5 inch CA0 (through 1.5 kohm)
4	STEP1	phase 1; 3.5 inch CA1
6	STEP2	phase 2; 3.5 inch CA2
7	3.5DSK	the 3.5 inch drive select (low when a 3.5 inch drive is addressed)
8	STEP3	phase 3; 3.5 inch LSTRB
10	WR_REQ	write request
11	VCC	+5 V from the Apple II
12	SELECT	SEL on the 3.5 inch port
14	DEVICE_ENABLE	drive enable (active low)
16	RD_DATA	read data (on a Macintosh also the status line)
18	WR_DATA	write data
20	WR_PROTECT	write protect (on the 3.5 inch port: the sense line; on a Macintosh an input to the drive)
9, 13, 15, 17, 19	not connected

Power

The 5 V of the Apple II arrives on connector pin 11 and goes through the fuse Fu1 (750 mA) and the diode D2, then to the 3.3 V regulator U1 (TLV1117LV33). The regulator accepts at most 5.5 V: never feed the power pins with more. The BlackPill has its own regulator and its own USB connector. Its 5 V pin and its 3.3 V pins are what the two jumpers connect to.

The text printed on the board:

WARNING:
ONLY 1 PWR SRC
- 3V
- 5V
- SDIO 3V

“3V” is the J7 / JP2 pair, “5V” is the J1 / JP1 pair and “SDIO 3V” is pin 1 of the ST-Link header J6. The board takes one power source at a time.

Situation	What to do
Running in the Apple II or the Macintosh	The computer is the only source. Close one of the two pairs: J1 / JP1 (“5V”: the Apple 5 V feeds the BlackPill, which makes its own 3.3 V) or J7 / JP2 (“3V”: the regulator U1 makes the 3.3 V for everything). Never close both
Updating the firmware over USB	USB is the only source: take the board out of the computer and remove the jumpers on J1 and J7
Flashing the bootloader with an ST-Link	The ST-Link is the only source: no USB, no Apple II, no jumpers on J1 and J7

A power-up without a card is safe: the board shows SD EJECTED and waits for the card.

What you need

For	You need
Every machine	A microSD card prepared as on page 03, and a 20 conductor ribbon cable with a 2 x 10 socket for J2
II+, IIe (Disk II emulation)	A Disk II controller card in a slot (slot 6 to boot), and the ribbon from the drive connector of that card to J2
II+, IIe (SmartPort emulation)	A card that speaks SmartPort: Liron, SoftSP6 or Yellowstone
IIc, IIgs	A cable from the drive port (DB-19) of the computer to the 20 pin header, wired as the table of J2 above
Macintosh	A cable from the external floppy port (DB-19) to the 20 pin header
Firmware work	A USB cable for the BlackPill. An ST-Link programmer only to install the bootloader the first time (page 04)

Three lines of the Macintosh floppy port are worth knowing when you make a cable:

DB-19 pin	Header pin	What it does
4	7	ground on a Macintosh (so the select line reads low)
10	20	an input to the drive on a Macintosh: the board never drives it
17	14	the external drive enable

On the Macintosh the status line moves to the read data pin (header pin 16). All the other lines are used as for the IIgs.

Pin 1 of J2 is a ground pin. Match the marked wire of the ribbon (the red one) to pin 1 and check the cable against the table above before you power anything.

Installing it in each machine

Always: the Apple II or Macintosh is off, the board has no other power source, and you insert the card last. Switch the computer off before you plug or unplug the cable.

Apple II+, II Europlus, IIe, with a Disk II controller card

1. Switch the computer off.
2. Plug the ribbon onto the drive connector of the Disk II controller card (slot 6 to boot from it) and onto J2 of the board.
3. Set the power pair for the computer as described in “Power”.
4. Insert the SD card, then switch the computer on.
5. The splash and then the main menu appear on the OLED. In Settings, choose the emulation type Disk II if it is not the one in use. A card without a configuration file starts with Disk II.
6. Mount an image from the file manager and boot the computer (Disk II emulation (5.25 inch)).

The same firmware and the Smartloader work on a stock IIe.

With a SmartPort card in a II+ or IIe (Liron, SoftSP6, Yellowstone)

Proceed as above, with the ribbon on the connector of the SmartPort card, and choose the emulation type SmartPort HD in Settings (SmartPort emulation (hard disk)).

Apple IIc

1. Switch the IIc off.
2. Connect the board to the external drive port (DB-19) of the IIc.
3. Choose Disk II or SmartPort HD emulation (08, 09).

The IIc ROM 4 is supported.

Apple IIgs

1. Switch the IIgs off.
2. Connect the board to the disk port (DB-19) of the IIgs.
3. Choose the emulation: Disk II (5.25 inch port), SmartPort, Smartloader, or the 3.5 inch drive (08, 09, Smartloader, 3.5 inch drive emulation (IIgs and Macintosh)).

A IIgs ROM 03 boots Disk II images, SmartPort images, the Smartloader and 3.5 inch images from the DB-19 port. The IIgs asks the SmartPort bus before it boots a 5.25 inch disk: the Disk II emulation ignores its own enable line then, so you do nothing special.

Macintosh with an external 800K floppy port

1. In Settings, set the emulation type to Disk 3.5.
2. Switch 3.5 Mac host on. ENTER on it asks (ENTER: host+reset). ENTER again saves it and the SmartDisk II restarts. The setting changes how the board drives its pins and is read when the emulation starts.
3. Switch 3.5 write on only if the Macintosh should write to the image.
4. Mount an image (.dc42, .2mg, .po, .img or .moof) from the menu.
5. Switch the Macintosh off and connect the board to the external floppy port (DB-19). To start from the image, start with the internal drive empty: a Macintosh looks at its internal drive first.
6. Switch the Macintosh on.

A Macintosh SE on its external drive port sees the drive, reads an image, and can write to it: Initialize of a blank 800K image completes. An HFS image made with Create disk is recognised.

The setting 3.5 SuperDrive (experimental) is in the same list when 3.5 Mac host is on. It makes the board answer as a SuperDrive, for 1.44 MB images on Macintosh models whose ROM supports one. ENTER asks, then saves and restarts the board.

The Macintosh mode, the eject and the images are described on 3.5 inch drive emulation (IIgs and Macintosh).

HD20 emulation (Macintosh): upcoming. It is not available in this firmware yet. The list of emulation types already shows an HD20 (Mac) entry: do not choose it, it does not work yet.

Which emulation for which connection

You connect to	Choose in Settings, Emulation type	Page
II+, II Europlus, IIe, Disk II controller card	Disk II	08
II+, IIe, SmartPort card	SmartPort HD	09
IIc (external drive port)	Disk II or SmartPort HD	08, 09
IIgs, 5.25 inch boot	Disk II	08
IIgs, hard disk volumes	SmartPort HD	09
IIgs, browse and boot from the Apple II screen	Smartloader	10
IIgs, 3.5 inch drive	Disk 3.5 (3.5 Mac host off)	11
Macintosh external 800K port	Disk 3.5 with 3.5 Mac host on	11

The Smartloader works on the IIe and the IIgs (10).

The case

The project has the files of a 3D printed case: a body in two variants (one for a high buzzer, one for a low buzzer), a top, a screen template, a navigation key, a key and a reset key, and the Fusion 360 file of the whole case.

Building it yourself

The gerber files of revision 8 are available on the project page on GitHub: https://github.com/vibr77/AppleIIDiskIIStm32F411.

You fit the BlackPill module, the OLED module and the buzzer by hand.

A new board needs the bootloader first (with an ST-Link on J6), then the firmware over USB: Firmware update.

Before the first power-up

1. One power source. Only one of J1 / JP1, J7 / JP2 closed, as the silkscreen says. No ST-Link, USB and Apple II together.
2. The OLED. The module pins on the board are in the order GND, +3.3V, SCL, SDA. Some OLED modules have the supply pins in the other order: compare your module with the silkscreen before you plug it in.
3. The cable. Check the orientation of the ribbon on J2 and on the Disk II controller card.
4. The card. FAT32 with 32 KB clusters, or use Make filesystem (The SD card). Without a card the board shows SD EJECTED.
5. On a board you built. Look for solder bridges on J2 and on the BlackPill pins. Check with a multimeter that the 5 V and 3.3 V rails are not shorted to ground. Check the diode and the fuse.

At the first start you see the splash with the logo and the version, for about half a second, then the main menu. A card without a configuration file gets a new sdiskConfig.json with the defaults: emulation Disk II, start at the menu (not on the last image), no sound, no screen saver, “5.25 write” on.

If the display shows Warning, ERROR: SD EJECTED, the card is not detected:

Then see Troubleshooting, FAQ and the log. The screens and keys are on Usage guide and OLED screens reference.

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