LM3S818 Luminary Micro, Inc, LM3S818 Datasheet - Page 30

• Manufacturer Part Number: LM3S818
• Description: Lm3s818 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

Architectural Overview
1.4.7.2
1.4.7.3
1.4.8
30
JTAG TAP Controller (Section 5 on page 40)
The Joint Test Action Group (JTAG) port provides a standardized serial interface for controlling the
Test Access Port (TAP) and associated test logic. The TAP, JTAG instruction register, and JTAG
data registers can be used to test the interconnects of assembled printed circuit boards, obtain
manufacturing information on the components, and observe and/or control the inputs and outputs
of the controller during normal operation. The JTAG port provides a high degree of testability and
chip-level access at a low cost.
The JTAG port is comprised of the standard five pins: TRST, TCK, TMS, TDI, and TDO. Data is
transmitted serially into the controller on TDI and out of the controller on TDO. The interpretation of
this data is dependent on the current state of the TAP controller. For detailed information on the
operation of the JTAG port and TAP controller, please refer to the IEEE Standard 1149.1-Test
Access Port and Boundary-Scan Architecture.
The LMI JTAG controller works with the ARM JTAG controller built into the Cortex-M3 core. This is
implemented by multiplexing the TDO outputs from both JTAG controllers. ARM JTAG instructions
select the ARM TDO output while LMI JTAG instructions select the LMI TDO outputs. The
multiplexer is controlled by the LMI JTAG controller, which has comprehensive programming for
the ARM, LMI, and unimplemented JTAG instructions.
System Control and Clocks (Section 6 on page 50)
System control determines the overall operation of the device. It provides information about the
device, controls the clocking of the device and individual peripherals, and handles reset detection
and reporting.
Hardware Details
Details on the pins and package can be found in the following sections:
Section 17, “Pin Diagram,” on page 360
Section 18, “Signal Tables,” on page 361
Section 19, “Operating Characteristics,” on page 371
Section 20, “Electrical Characteristics,” on page 372
Section 21, “Package Information,” on page 385
Preliminary
February 6, 2007