Clock Source; Usb Interface; Serial Port; Reset - Freescale Semiconductor FRDM-KL25Z User Manual

- 4 MHz and 32 kHz internal reference clock
- System oscillator supporting external crystal or resonator
- Low-power 1kHz RC oscillator for RTC and COP watchdog
 Analog peripherals
- 16-bit SAR ADC w/ DMA support
- 12-bit DAC w/ DMA support
- High speed comparator
 Communication peripherals
- Two 8-bit Serial Peripheral Interfaces (SPI)
- USB dual-role controller with built-in FS/LS transceiver
- USB voltage regulator
2
- Two I
C modules
- One low-power UART and two standard UART modules
 Timers
- One 6-channel Timer/PWM module
- Two 2-channel Timer/PWM modules
- 2-channel Periodic Interrupt Timer (PIT)
- Real time clock (RTC)
- Low-power Timer (LPT)
- System tick timer
 Human-Machine Interfaces (HMI)
- General purpose input/output controller
- Capacitive touch sense input interface hardware module

5.3.1 Clock Source

The Kinetis KL2 microcontrollers feature an on-chip oscillator compatible with three ranges of input
crystal or resonator frequencies: 32-40 kHz (low freq. mode), 3-8 MHz (high freq. mode, low range) and
8-32 MHz (high freq. mode, high range). The KL25Z128 on the FRDM-KL25Z is clocked from an 8 MHz
crystal.

5.3.2 USB Interface

The Kinetis KL2 microcontrollers feature a dual-role USB controller with on-chip full-speed and low-
speed transceivers. The USB interface on the FRDM-KL25Z is configured as a full-speed USB device. J5
is the USB connector for this interface.

5.3.3 Serial Port

The primary serial port interface signals are PTA1 and PTA2. These signals are connected to both the
OpenSDA and to the J1 I/O connector.

5.3.4 Reset

The PTA20/RESET signal on the KL25Z128 is connected externally to a pushbutton, SW1, and also to the
OpenSDA circuit. The reset button can be used to force an external reset event in the target MCU. The
reset button can also be used to force the OpenSDA circuit into bootloader mode. Please refer to
section 5.2, Serial and Debug Adapter (OpenSDA), for more details.
FRDMKL25ZUM FRDM-KL25Z User's Manual Page 9 of 14