User's Manual

7.5 LEDs
Six LEDs on the top side of the Nucleo board help the user during the application development.
Figure 12. LEDs location
1. LD1: this blue LED is available for user application.
2. LD2: this green LED is available for user application.
3. LD3: this red LED is available for user application.
4. LD4: this LED turns red to indicate that the current distribution cannot be performed as expected when the
board is supplied by USB_STLINK.
5. LD5: this LED turns green when the 5V is available. To select the 5 V source, refer to Section 7.1.3 for
further details.
6. LD6 is a bi-color LED, which default status is red. It turns to green to indicate that communication is in
progress between the host PC and ST-LINK/V2-1 with the following steps:
Slow blinking red and OFF: at power-on, before USB initialization
Fast blinking red and OFF: after the first correct communication between the host PC and ST-LINK/
V2-1 (enumeration)
Red ON: when initialization between the host PC and ST-LINK/V2-1 is successfully finished.
Green ON: after successful target communication initialization
Blinking red and green: during communication with the target
Green ON: communication is successfully finished and OK.
Orange ON: communication failure.
UM2823
LEDs
UM2823 - Rev 1
page 19/37