Stellaris® LM4F120 LaunchPad User’s Manual
14
August 29, 2012
Reset
The
RESET
signal into the LM4F120H5QR microcontroller connects to the RESET switch and to
the Stellaris® ICDI circuit for a debugger-controlled reset.
External reset is asserted (active low) under any of three conditions:
Power-on reset (filtered by an R-C network)
RESET switch held down
By the Stellaris® ICDI circuit when instructed by the debugger (this capability is optional, and
may not be supported by all debuggers)
Stellaris In-Circuit Debug Interface (ICDI) (Schematic on page 20)
Stellaris® In-Circuit Debug Interface (ICDI)
The Stellaris® LaunchPad evaluation board comes with an on-board Stellaris® In-Circuit Debug
Interface (ICDI). The Stellaris® ICDI allows for the programming and debug of the LM4F120H5QR
using LM Flash Programmer and/or any of the supported tool chains. Both JTAG and Serial Wire
Debug (SWD) are supported.
Table 2-7 shows the pins used for JTAG and SWD. These signals are also mapped out to easily
accessible breakout pads and headers on the board.
Virtual COM Port
When plugged in to a PC, the device enumerates as a debugger and a virtual COM port. Table 2-8
shows the connections for the COM port to the pins on the microcontroller.
Table 2-7. Stellaris® In-Circuit Debug Interface (ICDI) Signals
GPIO Pin
Pin Function
PC0
TCK/SWCLK
PC1
TMS/SWDIO
PC2
TDI
PC3
TDO/SWO
Table 2-8. Virtual COM Port Signals
GPIO Pin
Pin Function
PA0
U0RX
PA1
U0TX