QMK-based firmware for Magnavox Videowriter keyboard
Matrix layout is based on info from this article.
Magnavox Videowriter keyboard conversion project: direct connection of Pro Micro to the matrix.
- Keyboard Maintainer: DmNosachev
- Hardware Supported: Alps-based Magnavox Videowriter keyboard, Pro Micro 16MHz 5V MCU board (you can use any MCU which is supported by QMK and has 18 or more IO).
Make example for this keyboard (after setting up your build environment):
Videowriter has 8x10 matrix:
|0||51 LShift||39 Caps|
|1||08 Copy||07 Find||06 Split||05 Center||04 Page||03 Spell||02 Print||01 Menu|
|2||16 5||15 4||14 3||13 2||12 1||11 Delete||10 GoTo||09 Move|
|3||24 BkSpc||23 Equals||22 Minus||21 0||20 9||19 8||18 7||17 6|
|4||32 U||31 Y||30 T||29 R||28 E||27 W||26 Q||25 Tab|
|5||41 S||40 A||38 Return||37 ]||36 [||35 P||34 O||33 I|
|6||49 ;||48 L||47 K||46 J||45 H||44 G||43 F||42 D|
|7||58 M||57 N||56 B||55 V||54 C||53 X||52 Z||50 "|
|8||67 Left||66 Up||65 Insert||64 Space||63 Style||61 /||60 .||59 ,|
|9||62 RShift||72 Undo||71 Help||70 Do||69 Right||68 Down|
Separating Shift keys
Initially left and right Shift keys are connected in parrallel. You need to cut the traces from right Shift (switch 62) and wire it to column 2 (switch 65, right pin) and row 9 (switch 71, bottom pin).
Stock components removal
SN74LS145N IC (BCD-to-decimal decoder, drives matrix rows), NEC D8049HC IC (MCU, drives matrix columns) and resistor array need to be desoldered from the PCB. You need to shorten the 4 diodes (D2–D5) in the bottom right corner of the PCB (solder a wire between their pins). I've also removed two electrolytic capacitors and some ceramic capacitors just to free an additional space.
Optional: add diodes between each switch and corresponding row for NKRO. If you choose not to add them, create
config.h file in your personal keymap folder and add
#define MATRIX_HAS_GHOST to it.
Suggested mount position for the Pro Micro:
- Solder two 8-pin headers to the Pro Micro (pin D1-B5 on the left side and pins F4-B6 on the right side).
- Solder the Pro Micro to the Videowriter's PCB.
- Solder 6 wire bridges (pink color on the photo).
- By this point rows 0-4 and all columns will be already in place.
- Connect rows 5-9 (see right side of the PCB) to the corresponding pins of the Pro Micro using additional wires.
- Optional: connect a push button between Reset and Ground pins.
Compile and flash the firmware. Use matrix debug mode if something is wrong.