NXP Semiconductors TWR-KL28Z User Manual

NXP Semiconductors

Document Number: TWRKL28ZUG

User's Guide

Rev. 0

,

Contents

1. Introduction .................................................................... 1

2. Getting Started ................................................................ 2

3. TWR-KL28Z Features ..................................................... 2

4. TWR-KL28Z Hardware Description ................................ 4

4.1. Power supply ........................................................ 4

4.2. Serial and debug adapter (OpenSDA) .................... 5

4.3. Microcontroller ..................................................... 6

4.4. Capacitive touch pad ............................................. 9

4.5. I2C Accelerometer Sensor ..................................... 9

4.6. LED ................................................................... 11

4.7. Analog reference voltage..................................... 11

4.8. Input/output headers............................................ 12

5. References .................................................................... 13

6. Revision History ........................................................... 13

TWR-KL28Z User’s Guide

1. Introduction

The Tower development platform is a set of software
and hardware tools for evaluation and development. It is
an ideal tool for the rapid prototyping of
microcontroller-based applications.

The TWR-KL28Z supports power supply voltage range
from 1.71 V to 3.6 V. It features a KL28Z, a device
boasting a maximum operating frequency of 72 MHz,
up to 512 KB Flash and numerous analog and digital
peripherals.

The TWR-KL28Z includes the ARM open standard
embedded serial and debug adapter known as CMSIS­DAP. This circuit offers the user several options for
serial communications, flash programming, and run­control debugging.

The TWR-KL28Z microcontroller module is designed
to work either in standalone mode or as part of the
Tower System, a modular development platform that
enables rapid prototyping and tool re-use through
reconfigurable hardware.

© 2016 NXP B.V.

TWR-KL28Z Features

It can provide a broad range of expansion board options. The on-board interfaces include LED, a 3-axis
digital sensor (3D accelerometer), and two capacitive touch pads.

There are many software development tool options available to the user. Choices include Kinetis Design
Studio (KDS), IAR Embedded Workbench, Keil MDK featuring the µVision IDE, and so on.

All of these features combine to give users the Tower needed to rapidly prototype many embedded
designs: a powerful microcontroller built on a very low-power core and SOC platform, easy-access to
I/O with a large ecosystem of compatible hardware, a flexible programming and debug interface, and a
large ecosystem of software development environments.

2. Getting Started

Refer to the TWR-KL28Z Quick Start Package for step-by-step instructions for getting started with the

freedom board. See the “Jump Start Your Design” section at nxp.com/FREDEVPLA for the Quick Start

Package and software lab guides.

3. TWR-KL28Z Features

The TWR-KL28Z hardware is a Tower development board assembled with the following features:

• MKL28Z512VLL7 MCU (72 MHz, 512 KB Flash, 128 KB RAM, 32 KB ROM,100 LQFP

package)

• 3-Axis Digital Accelerometer, MMA8451Q

• On-board serial and debug adapter

• I/O headers for easy access to MCU I/O pins

• Flexible power supply options :USB, coin cell battery, external source

• Capacitive touch pad

• Reset push button

• NMI and LLWU buttons

• LEDs

The FRDM-KL28Z features two MCUs: The target MCU is the MKL28Z512VLL7. The CMSIS-DAP
MCU is the MK20DX128VFM5.

Figure 1 shows a block diagram of the TWR-KL28Z board. The primary components and their location

on the hardware assembly are pointed out in Figure 2.

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TWR-KL28Z Features

Figure 1. TWR-KL28Z block diagram

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Figure 2. TWR-KL28Z feature call-outs

TWR-KL28Z User’s Guide, Rev. 0, 06/2016

TWR-KL28Z Hardware Description

Supply Source & Location

Valid Range

CMSIS-DAP Operational?

Regulated on-board?

CMSIS-DAP USB (J10)

5 V

Yes

Yes

KL28Z USB (J29)

5 V

No

Yes

P3V3 Pin（J34 PIN2）

1.71-3.6 V

No

No

Power Supply Name

Description

P5V_miniUSB

Primary input power. Filtered from miniUSB connector

P5V_microUSB

Secondary input power. Filtered from microUSB connector

P5V_ELEV

Third input power from primary elevator connector.

P5V_TRG_USB

Output from USB power switch, which is controlled by the K20's VTRG_EN and elevator's

ELE_PS_SENSE.

V_BRD

Output from jumper header, to select 1.8 V, 3.3 V. Also could be supplied externally via

header pins

MCU_PWR

Output from jumper header, to select V_BRD, VREGOUT_KL28. Also could be supplied

externally via header pin

VDDA

Output from jumper header to select MCU_PWR. Also could be supplied externally via

header pin.

4. TWR-KL28Z Hardware Description

4.1. Power supply

The TWR-KL28Z offers a design with multiple power supply options. It can be powered from the USB
connector, the VIN pin on the I/O header, or an off-board 1.71-3.6 V supply from the 3.3 V pin on the
I/O header. The USB and VIN supplies are regulated on-board using a 3.3 V linear regulator to produce
the main power supply. The other sources are not regulated on-board.

The following table provides the operational details and requirements for the power supplies.

Table 1. Tags Power supply requirements

Figure 3 shows the schematic drawing for the power supply inputs and the on-board voltage regulator.

Figure 3. Power supply schematic

NOTE

The CMSIS-DAP circuit is operational only when a USB cable is
connected and supplying power to J10. However, the protection circuitry
is in place to allow multiple sources to be powered at once.

Table 2. FRDM-KL28Z power supplies

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TWR-KL28Z Hardware Description

4.2. Serial and debug adapter (CMSIS-DAP)

CMSIS –DAP is an open-standard serial and debug adapter. It bridges serial and debug communications
between a USB host and an embedded target processor as shown in Figure 4. CMSIS-DAP features a
mass storage device (MSD) bootloader, which provides a quick and easy mechanism for loading
different CMSIS-DAP Applications such as flash programmers, run-control debug interfaces, serial-to­USB converters, and more. Two or more CMSIS-DAP applications can run simultaneously. For
example, run-control debug application and serial-to-USB converter runs in parallel to provide a virtual
COM communication interface while allowing code debugging via CMSIS-DAP with just single USB
connection. These two applications are provided in a single code package. Refer to the CMSIS-DAP
User’s Guide for more details.

Figure 4. CMSIS-DAP block diagram

CMSIS-DAP is managed by a Kinetis K20 MCU built on the ARM Cortex-M4 core. The CMSIS-DAP
circuit includes a status LED (D1) and a RESET pushbutton (SW1). The pushbutton asserts the Reset
signal to the KL28Z target MCU. It can also be used to place the CMSIS-DAP circuit into bootloader
mode by holding down the RESET pushbutton while plugging the USB cable to USB connector J13.
Once the CMSIS-DAP enters bootloader mode, other CMSIS-DAP applications such as debug app can
be programmed. SPI and GPIO signals provide an interface to the SWD debug port of the KL28Z.
Additionally, signal connections are available to implement a UART serial channel. The CMSIS-DAP
circuit receives power when the USB connector is plugged into a USB host.

4.2.1. Debugging interface

Signals with SPI and GPIO capability are used to connect directly to the SWD of the KL28Z. These
signals are also brought out to a standard 10-pin Cortex Debug connector (J30) as shown in Figure 5. In
order to isolate the KL28Z MCU from the CMSIS-DAP circuit and use J30 to connect to an off-board

TWR-KL28Z User’s Guide, Rev. 0, 06/2016

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