TWR-K40X256 Freescale Semiconductor, TWR-K40X256 Datasheet - Page 10

• Manufacturer Part Number: TWR-K40X256
• Description: TOWER SYSTEM BOARD K40X256
• Manufacturer: Freescale Semiconductor
• Series: Kinetisr
• Type: MCUr

Specifications of TWR-K40X256

• Contents: Board
• Processor To Be Evaluated: K40
• Data Bus Width: 32 bit
• Interface Type: USB, CAN, I2C, SPI, UART
• Dimensions: 3.5 in x 3.2 in
• Operating Supply Voltage: 1.71 V to 3.6 V
• Silicon Manufacturer: Freescale
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M4
• Silicon Core Number: MK
• Silicon Family Name: Kinetis - K40
• Kit Contents: Board Only
• Rohs Compliant: Yes
• For Use With/related Products: Freescale Tower System, K40X256
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2.3 System Power
In stand-alone operation, the power source for the TWR-K40X256 module is derived from the 5.0V
input from either the USB mini-B connector, J16, or the debug header, J14, when a shunt is placed on
jumper J15. A low-dropout regulator provides a 3.3V supply from the 5.0V input voltage. Refer to
sheet 5 of the TWR-K40X256 schematics for more details.
When installed into a Tower System, the TWR-K40X256 can be powered from either an on-board
source or from another source in the assembled Tower System. If both the on-board and off-board
sources are available, the TWR-K40X256 will default to the off-board source.
The 3.3V power supplied to the MCU is routed through a jumper, J11. The jumper shunt can be
removed to allow for either 1) alternate MCU supply voltages to be injected or 2) the measurement of
power consumed by the MCU.
2.3.1 RTC VBAT
The Real Time Clock (RTC) module on the K40 has two modes of operation, system power-up and
system power-down. During system power-down, the RTC is powered from the backup power supply,
VBAT. The TWR-K40X256 provides a battery holder for a coin cell battery that can be used as the VBAT
supply. The holder can accept common 20mm diameter 3V lithium coin cell batteries (e.g. 2032,
2025). Refer to the description J12 in Table 5 “TWR-K40X256 Jumper Table” for more information.
2.4 Debug Interface
There are two debug interface options provided: the on-board OSJTAG circuit and an external Cortex
Debug+ETM connector.
2.4.1 OSJTAG
An on-board MC9S08JM60 based Open Source JTAG (OSJTAG) circuit provides a JTAG debug interface
to the K40X256. A standard USB A male to Mini-B male cable (provided) can be used for debugging via
the USB connector, J16. The OSJTAG interface also provides a USB to serial bridge. Drivers for the
OSJTAG interface are provided in the P&E Micro Kinetis Tower Toolkit (available on the included DVD).
Note: The port pins connected to the OSJTAG USB-to-serial bridge (PTD6 and PTD7) are also connected
to the infrared interface. Refer to Table 6 “I/O Connectors and Pin Usage Table” and Table 5 “TWR-
K40X256 Jumper Table” for more information.
8.0 MHz Resonator
32.768 KHz RTC Crystal
Clock Input from CLKIN0
"X" indicates that the resistor is installed; "―" indicates that the resistor is not
populated. All resistor values are 0 ohm.
MCG Oscillator Input
TWR-K40X256 Tower Module User's Manual
Table 1. MCG oscillator input selection resistor settings
R93 R91 R95 R97 R81 R88 R87 R86 R83 R84
―
X
X
―
―
X
―
X
X
―
―
X
―
―
X
―
―
X
―
―
X
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―
―
X
―
―
X
―
―
X