KWIKSTIKK40UM

KwikStik-K40 User's Manual

Page 8 of 19

SPI, I

SD Host Controller (SDHC)

GPIO with pin interrupt support, DMA request capability, digital glitch filtering

Capacitive touch sensing inputs (TSI)

LCD display driver supporting 3V and 5V glass, configurable frontplane and backplane pins, and

segment failure detection

Debug interfaces: JTAG, cJTAG, SWD

Trace: TPIO, FPB, DWT, ITM, ETM, ETB

2.2 Clocking

The Kinetis MCUs start up from an internal digitally controlled oscillator (DCO). Software can enable

one or two external oscillators if desired. The external oscillator for the Multipurpose Clock Generator

(MCG) module can range from 32.768 kHz up to a 32 MHz crystal or ceramic resonator. The external

oscillator for the Real Time Clock (RTC) module accepts a 32.768 kHz crystal.

Figure 5. External clock source circuitry

The clocking circuitry on the KwikStik is shown on sheet 7 of the schematics and in Figure 5. A 4.0 MHz

ceramic resonator with built-in load capacitors is the default external source for the MCG oscillator

inputs (XTAL/EXTAL_MAIN). A 32.768 KHz crystal is connected to the RTC oscillator inputs by default.

2.3 System Power

The main power source for the KwikStik comes from either one of the two Micro USB ports. When

plugged in, power for the system is derived from a Freescale MC34727CFCR2 3.3V regulator.

When installed into a Tower System, the KwikStik can be powered from either an on-board source or

from another source in the assembled Tower System.

Switching the ON/OFF switch to the OFF position will cut power supply to the K40X256 MCU. The

JM128 will remain powered even if the switch is in the OFF position, enabling the KwikStik for external

programming. Refer to section 2.4, “Debug Interface” for information on how to use the on board

SEGGER J-link debug interface. Refer to Figure 6 for location and correct usage of the ON/OFF switch.