LM3S1621 Datasheet, PDF (183/947 Pages) Texas Instruments – ARM and Thumb are registered trademarks and Cortex is a trademark

Stellaris^® LM3S1621 Microcontroller
If the application only uses the internal POR circuit, the RST input must be connected to the power
supply (V_DD) through an optional pull-up resistor (0 to 100K Ω) as shown in Figure 5-1 on page 183.
Figure 5-1. Basic RST Configuration
VDD
Stellaris®
R_PU
RST
R_PU = 0 to 100 kΩ
The external reset pin (RST) resets the microcontroller including the core and all the on-chip
peripherals except the JTAG TAP controller (see “JTAG Interface” on page 168). The external reset
sequence is as follows:
1. The external reset pin (RST) is asserted for the duration specified by T_MIN and then de-asserted
(see “Reset” on page 890).
2. The internal reset is released and the core loads from memory the initial stack pointer, the initial
program counter, and the first instruction designated by the program counter, and then begins
execution.
To improve noise immunity and/or to delay reset at power up, the RST input may be connected to
an RC network as shown in Figure 5-2 on page 183.
Figure 5-2. External Circuitry to Extend Power-On Reset
VDD
Stellaris®
R_PU
RST
C₁
R_PU = 1 kΩ to 100 kΩ
C₁ = 1 nF to 10 µF
If the application requires the use of an external reset switch, Figure 5-3 on page 184 shows the
proper circuitry to use.
January 21, 2012
183
Texas Instruments-Production Data