You'll need `make clean` after you edit **config.h** or change options like `KEYMAP`.
Frist remove all files made in previous build,
$ make clean
then build new frimware.
$ make [KEYMAP=...]
Also you can always try `make clean` when you get other strange result during build.
## WINAVR is obsolete
It is no longer recommended and may cause some problem.
See [Issue #99](https://github.com/tmk/tmk_keyboard/issues/99).
## USB stack: LUFA or PJRC?
Use **LUFA**.
**PJRC** stack won't be supported actively anymore. There is no reason to hesitate to use LUFA except for binary size(about 1KB lager?). But **PJRC** is still very useful for debug and development purpose.
See also [Issue #50](https://github.com/tmk/tmk_keyboard/issues/50) and [Issue #58](https://github.com/tmk/tmk_keyboard/issues/58).
## Edit configuration but not change
Try these.
### 1. make clean
This will be needed when you edit **config.h**.
### 2. Remove Drivers from Device Manager(Windows)
Windows only. Linux, OSX and other OS's doesn't require this. It looks like Windows keeps using driver installed when device was connected first time even after the device changes its configuration. To load proper drivers for new configuration you need to remove existent drivers from **Drvice Manager**.
You will need this after editing `CONSOLE_ENABLE`, `NKRO_ENABLE`, `EXTRAKEY_ENABLE` or `MOUSEKEY_ENABLE` option in **Makefile**.
You can use any ID you want with editing `config.h`. Using any presumably unused ID will be no problem in fact except for very least chance of collision with other product.
Use `1UL<<16` intead of `1<<16` in `read_cols()` in **matrix.h** when your columns goes beyond 16.
In C `1` means one of **int** type which is **16bit** in case of AVR so you can't shift left more than 15. You will get unexpected zero when you say `1<<16`. You have to use **unsigned long** type with `1UL`.
In Windows check `Allow this device to wake the computer` setting in Power **Management property** tab of **Device Manager**. Also check BIOS setting.
Pressing any key during sleep should wake host.
## Using Arduino?
**Note that Arduino pin naming is different from actual chip.** For example, Arduino pin `D0` is not `PD0`. Check circuit with its schematics yourself.
Arduino leonardo and micro have **ATMega32U4** and can be used for TMK, though Arduino bootloader may be a problem.
## Using PF4-7 pins of USB AVR?
You need to set JTD bit of MCUCR yourself to use PF4-7 as GPIO. Those pins are configured to serve JTAG function by default. MCUs like ATMega*U* or AT90USB* are affeteced with this.
If you are using Teensy this isn't needed. Teensy is shipped with JTAGEN fuse bit unprogrammed to disable the function.
See this code.
```
// JTAG disable for PORT F. write JTD bit twice within four cycles.
