Skip to content

README.md

Latest commit

 

History

History
85 lines (63 loc) · 2.96 KB

README.md

File metadata and controls

85 lines (63 loc) · 2.96 KB

PS/2 to USB Keyboard Converter

This subdirectory of AAKBD contains the components specific to the PS/2 to USB keyboard converter, ps2usb. See the main README for details about the entire USB keyboard implementation.

Hardware

The implementation has been tested with ATMEGA32U4 running at 5V with a 16 MHz crystal oscillator, in particular with an Arduino Pro Micro clone.

The pinout is as follows:

  • PS/2 CLK – pin D0
  • PS/2 DATA – pin D1
  • status LED – pin B0
  • error LED – pin D5

This also corresponds to an Arduino Pro Micro with the existing LEDs already in place. On the Pro Micro, PS/2 CLK is "pin 3" and PS/2 DATA is "pin 2", in their silly renumbering scheme. You may add an external pull-up resistor between each of those pins and 5V (RAW), for example, 4.7KΩ or more. However, the internal pull-ups are also enabled and in my experiments no keyboard I tested needed the external resistors.

Connecting the LEDs is optional, just as long as nothing breaks if those pins are driven high (i.e., unconnected is fine).

No other components are needed, apart from the physical connectors.

Configuration

Set DEVICE to ps2usb either in local.mk (in the project root directory), or on the command line (i.e., make DEVICE=ps2usb).

You can have two complementary local.mk files: one the the project root directory, and ps2usb/local.mk specific to this PS/2 to USB converter.

For example:

# root local.mk
DEVICE = ps2usb

MAX_KEY_ROLLOVER = 7

CONFIG_FLAGS =  \
	       -DUSB_MAX_KEY_ROLLOVER=$(MAX_KEY_ROLLOVER) \
	       -DUSB_VENDOR_ID=$(VENDOR_ID) \
	       -DUSB_PRODUCT_ID=$(PRODUCT_ID) \
	       -DMANUFACTURER_STRING='$(MANUFACTURER)' \
	       -DPRODUCT_STRING='$(PRODUCT)' \
	       -DKEYBOARD_POLL_INTERVAL_MS=2 \
	       -DENABLE_BOOTLOADER_SHORTCUT=1
# ps2usb/local.mk

VENDOR_ID = 0x04B3U
PRODUCT_ID = 0x3020U

MANUFACTURER = "IBM Corp."
PRODUCT = "Model M Keyboard"

This example configuration misuses an IBM keyboard's vendor and product id. However, is it really misuse if the actual keyboard is made by IBM? ;> In any case, unauthorised use of ids must be limited to personal DIY projects, not any released products!

After creating this file, run make once to create layers.c and macros.c from the included templates. These files are created in this ps2usb directory. If you wish, you can move one or both of them to the project root directory.

You may then edit layers.c and macros.c to configure the keyboard. Note that while the template provides some examples, it is not enabled due to LAYER_COUNT being defined as 0 in layers.c. To enable your layers, you must increase LAYER_COUNT to the number of your highest layer. Layer numbers start from 1 (layer 0 is the implicit "default layer", i.e., for this PS/2 to USB converter it maps each PS/2 keycode to the corresponding USB keycode).

Recompile by running make again.