TWRKL43ZUG Tower Module, User’s Guide, Rev. 1, 08/2014
6
Freescale Semiconductor, Inc.
Hardware description
In standalone operation, the main power source (5.0V ) for the TWR-KL43Z48M module is derived from
either the OpenSDA USB micro-AB connector or the KL43 USB micro-AB connector (J5). Two
low-dropout regulators provide 3.3V and 1.8V supplies from the 5.0V input voltage. Additionally, the
3.3V regulator built into the KL43 can be selected to power the 3.3V bus. All the user selectable options
can be configured using two headers, J35, J25 or J28.
6.5
Real-time clock (RTC)
Y1 is a 32.768 kHz oscillator that can be connected to RTC_CLKIN via selection header J31. By enabling
the external clock input option in the RTC, it can be used as a highly precise time reference.
6.6
Debug interface
There are two debug interface options provided: the on-board OpenSDA circuit and an external ARM
SWD connector.
6.6.1
OpenSDA
An on-board MK20-OpenSDA circuit provides an SWD debug interface to the MKL43Z256. A standard
USB A male to micro-AB male cable (provided) can be used for debugging via the USB connector, J8.
The OpenSDA interface also provides a USB to serial bridge.
6.6.2
Cortex Debug SWD connector
The Cortex Debug SWD connector is a standard 2x5-pin (0.05") connector providing an external debugger
cable with access to the SWD interface of the MKL43Z256.
Table 2. Cortex Debug connector
Pin
Function
TWR-KL43Z Connection
1
VTref
3.3V MCU supply (V_BRD)
2 SWDIO
PTA3/I2C1_SCL/FTM0_CH0/SWD_DIO
3 GND
GND
4 SWCLK
PTA0/
FTM0_CH5
/SWD_CLK
5 GND
GND
6 NC
7 NC
8 NC
9 NC
10 nRESET
PTA20/RESET
