Texas Instruments EK-TM4C123GXL, Руководство пользователя

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In-Circuit Debug Interface (ICDI)
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There is no external battery source on the Tiva C Series LaunchPad Hibernation module, which means
the VDD3ON power control mechanism should be used. This mechanism uses internal switches to
remove power from the Cortex-M4 processor as well as to most analog and digital functions while
retaining I/O pin power.
To measure the Hibernation mode current or the Run mode current, the VDD jumper that connects the 3.3
V pin and the MCU_PWR pin must be removed. See the complete schematics (appended to this
document) for details on these pins and component locations. An ammeter should then be placed
between the 3.3 V pin and the MCU_PWR pin to measure I
DD
(or I
HIB_VDD3ON
). The TM4C123GH6PM
microcontroller uses V
DD
as its power source during V
DD3ON
Hibernation mode, so I
DD
is the Hibernation
mode (VDD3ON mode) current. This measurement can also be taken during Run mode, which measures
I
DD
the microcontroller running current.
2.2.3 Clocking
The Tiva C Series LaunchPad uses a 16.0-MHz crystal (Y2) to complete the TM4C123GH6PM
microcontroller main internal clock circuit. An internal PLL, configured in software, multiples this clock to
higher frequencies for core and peripheral timing.
The Hibernation module is clocked from an external 32.768-KHz crystal (Y1).
2.2.4 Reset
The RESET signal into the TM4C123GH6PM microcontroller connects to the RESET switch and to the
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 ICDI circuit when instructed by the debugger (this capability is optional, and may not be
supported by all debuggers)
2.3 In-Circuit Debug Interface (ICDI)
The Tiva C Series LaunchPad evaluation board comes with an on-board In-Circuit Debug Interface (ICDI).
The ICDI allows for the programming and debug of the TM4C123GH6PM using the LM Flash Programmer
and/or any of the supported tool chains. Note that the ICDI supports only JTAG debugging. An external
debug interface can be connected for Serial Wire Debug (SWD) and SWO (trace).
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.
Table 2-7. In-Circuit Debug Interface (ICDI) Signals
GPIO Pin Pin Function
PC0 TCK/SWCLK
PC1 TMS/SWDIO
PC2 TDI
PC3 TDO/SWO
2.3.1 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 2-8. Virtual COM Port Signals
GPIO Pin Pin Function
PA0 U0RX
PA1 U0TX
12 Hardware Description SPMU296 – April 2013
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