diff --git a/keyplus_mini/rev2/README.md b/keyplus_mini/rev2/README.md
new file mode 100644
index 0000000..7387983
--- /dev/null
+++ b/keyplus_mini/rev2/README.md
@@ -0,0 +1,137 @@
+# keyplus mini beta
+
+## Errata rev2
+
+The SS and MO pins are mislabeled. The SS pin should be MO, and the MO pin
+should be SS.
+
+## Wiring
+
+### Wiring key matrix
+
+The key matrix should be wired to the ROW and COL pins on the PCB. Wiring of the
+ROW and COL and column pins should start from the lowest number pin (i.e. `ROW0`
+and `COL0`) and work up in consecutive order. The diodes in the key matrix should
+point from the COL to ROW pins (other scan modes not implemented yet).
+
+The `COL15, COL14, COL13, COL12` pins (underlined on the PCB) may also be used
+as `ROW` pins. They map to the following row pins:
+
+* ROW6: COL15
+* ROW7: COL14
+* ROW8: COL13
+* ROW9: COL12
+
+Thus it is possible to have up to 120 keys connected using a 10x12 matrix.
+
+### Wired split with I2C
+
+To connect to boards with I2C for wired split, connect the 5V, SDA, SCL, and
+GND pins between devices. You can connect several devices in this manner, they
+just need to share 5V, SDA, SCL and GND pins.
+
+I would recommend **NOT** using TRRS connectors for wired split. While connecting and
+disconnecting the device the contacts inside the TRRS cable can short to one
+another. Instead I would recommend using micro USB ports, or another
+connector that doesn't short it's contacts when it is plugged/unplugged. Then
+you will be able to take advantage of the wireless/wired hot plugging
+functionality without worrying about damaging the hardware.  You can find
+male-to-male micro USB cables online with a bit of searching.
+
+### Wireless with nRF24L01+
+
+To use wireless mode, you will need a battery and a nRF24L01+ module. The
+battery should be 3V. Some options for the battery are 1xCR2032, 2xAA/AAA, or
+1xAA/AAA with a boost converter. Note the keyplus mini controller does not
+support any sort of charging of the batteries. When there is no USB connecting
+the device will run off battery power. When the USB is plugged in, it will
+automatically switch to run off USB power. To connect the battery connect:
+
+* BAT -> positive battery terminal
+* GND -> negative battery terminal
+
+To connect an nRF24L01+ module you will need to connect these pins:
+
+* xmega -> nRF24L01+
+* R0 -> CE
+* R1  -> IRQ
+* MO -> MO / MOSI  (Note: rev2 PCB use SS instead)
+* MI -> MI / MISO
+* SS -> SS / CSN (Note: rev2 PCB use MO instead)
+* SCK -> SCK
+
+![surface mount nRF24L01+ module pin out](https://raw.githubusercontent.com/ahtn/keyplus/master/notes/mini-nrf24l01-smd.jpg)
+
+Note: currently the IRQ pin is not used in the code, but I'll add code to take advantage of it soon.
+
+### PCB schematic for rev 2
+
+[Schematic for keyplus mini](https://rawgit.com/ahtn/keyboard_pcb/bb20b354216aa1858254db9946aa67aa8df67bfd/keyplus_mini/rev2/keyplus_mini.pdf)
+
+### Mechanical information for rev 2
+
+![keyplus mini mechanical information](https://rawgit.com/ahtn/keyboard_pcb/bb20b354216aa1858254db9946aa67aa8df67bfd/keyplus_mini/rev2/mechanical.png)
+
+## Layout file format and programming
+
+TODO
+
+For the mean time, refer to the [example layouts](https://github.com/ahtn/keyplus/tree/master/layouts), and the [list of available keycodes](https://github.com/ahtn/keyplus/blob/master/host-software/layout/mapped_keycodes.py#L8).
+
+## Current firmware limitations
+
+Firmware is still in beta and several features are not completely
+finished yet. Some prominent ones:
+
+* Macro and hold keycodes can't be used in the layout config file yet.
+* No LED support yet (including indicators)
+* Pairing unifying mouse is not exposed to devices yet
+
+## Testing key matrix
+
+The firmware supports a mode where it will pass the raw keyboard matrix data to
+the PC. This can be used to check the row and column pairs in your key matrix.
+Currently, this can only be used on the command line using a python script
+[`keyplus/host-software/keyplus_cli.py`](https://github.com/ahtn/keyplus/blob/master/host-software/keyplus_cli.py).
+
+To use the keyboard matrix passthrough mode, run `./keyplus_cli.py passthrough`
+and you should see output like this:
+
+```
+$$ ./keyplus_cli.py passthrough
+r3c5
+
+r3c0
+
+r1c0
+
+r0c1
+r0c1 r1c1
+r1c1
+r1c1 r3c3
+r3c3
+```
+
+Where each line shows which keys in the matrix are currently being pressed.
+Note only devices directly connected by USB will report key presses using
+passthrough mode.
+
+## xusb bootloader
+
+The bootloader installed on the ATxmega is the [xusb bootloader](https://github.com/ahtn/xusb-boot).
+To enter bootloader mode press the reset button (or short the RST and GND
+contacts) once when the USB cable is plugged in. The device will remain in
+bootloader mode until it is programmed, or until the reset button is pressed a
+second time.  For a more detailed explanation of the bootloader, [see
+here](https://github.com/ahtn/xusb-boot#ways-to-enter-the-bootloader).
+
+The lock bits on the ATxmega have been set to disable reading from flash by an
+external programmer. This is done to protect the encryption keys that are
+stored in flash.  Also, for security reasons the bootloader will wipe SRAM on
+power up.
+
+## Trouble shooting
+
+* Make sure that the battery contacts have a firm connection. I've had issues
+  sometimes with my homemade CR2032 holders where vibrations from typing would
+  cause the contacts to be unreliable.