Added a reset switch to my Model M

[Fujisawa Rob]

I am using the USB adapter sold at Clickykeyboards (although I didn't buy it there), and while it usually works fine, sometimes when my laptop wakes up, the keyboard isn't responsive. Typically, I was just unplugging the cord from the back of the keyboard which fixed it. I've done the pull-up resistor mod, but it made no difference. So, I added a simple pushbutton momentary switch that connects between pins 1 and 2 (Vss and /RST) of the 6805 controller. It works great!

[Fujisawa Rob]

Nice and clean, and won't accidentally be hit:


Inside:


Soldered to the back of the board, sorry, no pic. It was a bit of a pain but it does work:

[gnubag]

nice.

would be cool if you used a mx switch

[Findecanor]

Elegant mod!

would be cool if you used a mx switch

I think it would have been cooler if the reset switch had been salvaged from IBM equipment from the same time era as the keyboard.

[daerid]

This is why I love GeekHack

[SpAmRaY]

Need to remember this for future build ideas!

[Fujisawa Rob]

Elegant mod!

would be cool if you used a mx switch

I think it would have been cooler if the reset switch had been salvaged from IBM equipment from the same time era as the keyboard.

Like the Big Red Switch on a PC/AT power supply?

I actually bought a nc/no switch, thinking I could splice it in between the +5v line with the N.C. side, but with everything on-board that was too difficult. Fortunately, I was able to use the N.O. side on the reset pin.  I wish I knew why this was necessary, maybe it's a problem with the adapter, or the usb port, but I'm satisfied with this fix for now. As long as you don't mind drilling a hole in your keyboard...

Thank you for the compliments.

[mich]

I wish I knew why this was necessary, maybe it's a problem with the adapter, or the usb port, but I'm satisfied with this fix for now.

What's the state of LEDs when it doesn't work?

In Model Ms and M2s the NL led is driven directly by a normally-low MCU GPIO while CL and SL are driven through inverters. Hence normal boot looks like this:

Code: [Select]

0-0-0 - no power, all leds off
0-1-1 - power-up, MCU GPIOs low, inverters light up CL and SL
0-0-0 - firmware boots up and drives CL and SL pins high, inverters clear the LEDs
1-1-1 - short blink after (successful?) POST
0-0-0
x-x-x - whatever the host controller wants
If CL and SL stay permanently lit, it's likely an MCU crash caused by attempting to boot during voltage dip caused by inrush current to other devices, an issue similar to this one. If they get cleared and blink, it's probably some problem with this USB-PS/2 controller.

[Fujisawa Rob]

I wish I knew why this was necessary, maybe it's a problem with the adapter, or the usb port, but I'm satisfied with this fix for now.

What's the state of LEDs when it doesn't work?

In Model Ms and M2s the NL led is driven directly by a normally-low MCU GPIO while CL and SL are driven through inverters. Hence normal boot looks like this:

Code: [Select]

0-0-0 - no power, all leds off
0-1-1 - power-up, MCU GPIOs low, inverters light up CL and SL
0-0-0 - firmware boots up and drives CL and SL pins high, inverters clear the LEDs
1-1-1 - short blink after (successful?) POST
0-0-0
x-x-x - whatever the host controller wants
If CL and SL stay permanently lit, it's likely an MCU crash caused by attempting to boot during voltage dip caused by inrush current to other devices, an issue similar to this one. If they get cleared and blink, it's probably some problem with this USB-PS/2 controller.

Oops...I never saw your reply. Not sure, I'll make a note next time it happens. Is there a way to add an external 5v power supply inline with the PS2 port, bypassing the power from the USB adapter?

[bazemk1979]

Nice and clean, and won't accidentally be hit:

Show Image

Inside:

Show Image

Soldered to the back of the board, sorry, no pic. It was a bit of a pain but it does work:

Show Image

can it turn on and off the light bulb in your room?