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Diffstat (limited to 'docs/faq_debug.md')
| -rw-r--r-- | docs/faq_debug.md | 17 |
1 files changed, 5 insertions, 12 deletions
diff --git a/docs/faq_debug.md b/docs/faq_debug.md index f6cc729b61..5cc20251d3 100644 --- a/docs/faq_debug.md +++ b/docs/faq_debug.md @@ -184,22 +184,15 @@ Pressing any key during sleep should wake host. Arduino Leonardo and micro have **ATMega32U4** and can be used for TMK, though Arduino bootloader may be a problem. +## Enabling JTAG -## 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 affected with this. +By default, the JTAG debugging interface is disabled as soon as the keyboard starts up. JTAG-capable MCUs come from the factory with the `JTAGEN` fuse set, and it takes over certain pins of the MCU that the board may be using for the switch matrix, LEDs, etc. -If you are using Teensy this isn't needed. Teensy is shipped with JTAGEN fuse bit unprogrammed to disable the function. +If you would like to keep JTAG enabled, just add the following to your `config.h`: -See this code. +```c +#define NO_JTAG_DISABLE ``` - // JTAG disable for PORT F. write JTD bit twice within four cycles. - MCUCR |= (1<<JTD); - MCUCR |= (1<<JTD); -``` -https://github.com/tmk/tmk_keyboard/blob/master/keyboard/hbkb/matrix.c#L67 - -And read **26.5.1 MCU Control Register – MCUCR** of ATMega32U4 datasheet. - ## Adding LED Indicators of Lock Keys You need your own LED indicators for CapsLock, ScrollLock and NumLock? See this post. |