NXP Semiconductors FRDM-K28F User manual

© 2017 NXP B.V.
Freedom Board for Kinetis K28F
(FRDM-K28F)
1.Introduction
The Freedom development platform is a set of software
and hardware tools for evaluation and development. It
is ideal for rapid prototyping of MCU-based
applications. The Freedom K28 board (FRDM-K28F)
is a simple yet sophisticated design featuring the
Kinetis K series MCU built upon the ARM®
Cortex®-M4 core which features a Floating-Point Unit
(FPU).
FRDM-K28F can be used to evaluate the K27 and K28
Kinetis K series MCUs. The FRDM-K28F board
features the MK28FN2M0VMI15 MCU which features
a maximum operating frequency of 150 MHz, 2 MB
flash, 1 MB RAM, high-speed and full-speed USB
controller with available crystal-less operation,
SDRAM controller, secure digital host controller,
QuadSPI controller, and analog and digital peripherals.
The FRDM-K28F hardware is form-factor compatible
with the Arduino™R3 pin layout, providing a broad
range of expansion board options. The on-board
interface includes a 6-axis digital accelerometer and
magnetometer, RGB LED, FlexIO socket, SD card
interface, mobile SDRAM memory, and external serial
flash memory.
NXP Semiconductors
Document Number: FRDMK28FUG
User's Guide
Rev. 0
,
04/2017
Contents
1. Introduction........................................................................1
2. FRDM-K28F hardware overview ......................................2
3. FRDM-K28F hardware description....................................4
3.1. Power supply...........................................................4
3.2. Serial and Debug Adapter version 2 (OpenSDA
v2.2) ................................................................................7
4. MCU ..................................................................................9
5. Clocking...........................................................................10
6. Universal Serial Bus (USB) .............................................11
7. VBAT...............................................................................12
8. Accelerometer and magnetometer....................................13
9. RGB LED.........................................................................14
10. Serial port.........................................................................15
11. QuadSPI memory.............................................................15
12. Mobile SDRAM memory.................................................15
13. Secure Digital (SD) card..................................................15
14. FlexIO socket...................................................................16
15. Reset.................................................................................17
16. Push-button switches........................................................17
17. Visible light sensor...........................................................18
18. Debug...............................................................................19
19. Input/output connectors....................................................19
20. Arduino compatibility......................................................20
21. Jumper table.....................................................................20
22. References........................................................................21
23. Revision history ...............................................................21

FRDM-K28F hardware overview
Freedom Board for Kinetis K28F (FRDM-K28F), User's Guide, Rev. 0, 04/2017
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FRDM-K28F features OpenSDA v2.2, the open-source hardware embedded serial and debug adapter
running an open-source bootloader. This circuit offers several options for serial communication, flash
programming, and run-control debugging. OpenSDA v2.2 is an mbed™HDK-compatible debug
interface pre-loaded with the open-source DAP link interface firmware for rapid prototyping and
product development with focus on the connected Internet of Things (IoT) devices.
2.FRDM-K28F hardware overview
The features of the FRDM-K28F board are:
•Kinetis MK28FN2M0VMI15 MCU (ARM Cortex-M4 at150 MHz, 1 MB SRAM, 2 MB flash,
HS and FS USB, 169 MAPBGA package).
•Kinetis K20 MCU (K20DX128VFM5) based OpenSDA circuit.
•Dual-role high-speed and full-speed USB interface with the micro-B USB connector via the
high-speed switch.
•One 256 Mbit (32 MB) on-board QuadSPI memory at 1.8 V.
•One 128 Mbit (16 MB) on-board mobile SDRAM memory at 3.3 V.
•Multiple independent voltage domains: VDD_CORE, VDD, VBAT, and VDDIO_E.
•FlexIO socket which enables you to connect an optional TFT Proto 5” CAPACITIVE from
MikroElektronika (5” display board with capacitive touch).
•Easy access to the MCU input/output through Arduino R3-compatible I/O connectors to connect
external add-on boards.
•Flexible power supply option—OpenSDA v2.2 USB, Kinetis K28 USB, or an external source.
•FXOS8700CQ—6-axis sensor with accelerometer and magnetometer.
•RGB LED.
•Two mechanical push-buttons for user input and one for the reset.
•Programmable OpenSDA v2.2 debug circuit supporting the DAP-Link interface software which
provides:
—Mass-Storage Device (MSD) flash programming interface.
—CMSIS-DAP debug interface over a driverless USB HID connection providing
run-control debugging and compatibility with the IDE tools.
—Virtual serial port interface.
—Open-source CMSIS-DAP software project.
Figure 1 shows the block diagram of the FRDM-K28F board. The primary components and their
placement on the hardware assembly are shown in Figure 2.

FRDM-K28F hardware overview
Freedom Board for Kinetis K28F (FRDM-K28F), User's Guide, Rev. 0, 04/2017
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Figure 1. FRDM-K28F block diagram

FRDM-K28F hardware description
Freedom Board for Kinetis K28F (FRDM-K28F), User's Guide, Rev. 0, 04/2017
4 NXP Semiconductors
Figure 2. FRDM-K28F primary component placement
3.FRDM-K28F hardware description
3.1. Power supply
There are multiple power supply options on the FRDM-K28F board. It can be powered from either of
the USB connectors, the VIN pin on the I/O header, or an off-board 1.71 V–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 and a 1.8 V linear regulator to produce the VDDIO_E power supply.
A direct voltage supply to the K28F MCU is also available via J18, J15, and J22. The following table
provides the operational details and requirements for the power supplies.

FRDM-K28F hardware description
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Table 1. FRDM-K28F power requirements
Supply source
Valid range
OpenSDA v2.2 operational
Regulated on-board
OpenSDA v2.2 USB
5 V
Yes
Yes
K28F USB
5 V
No
Yes
P5-9V_VIN pin
5 V–9 V
No
Yes
3.3 V VDD header (J18)
1.71 V–3.6 V
No
No
1.8 V VDDIO_E header (J15)
1.71 V–3.6 V
No
No
1.2 V VDD_CORE header (J22)
1.17 V–1.32 V (RUN mode)
1.33 V–1.47 V (HSRUN mode)
No
No
NOTE
The OpenSDA v2.2 circuit is only operational when a USB cable is
connected and supplies power to the OpenSDA v2.2 USB. However, a
protection circuitry is provided to enable multiple sources to be powered
at once. By default, the FRDM-K28F VDD_CORE = 1.2 V is operating in
the RUN mode. To operate in the HSRUN mode, supply 1.33 V–1.47 V
externally.
CAUTION
When 3.3 V is supplied directly through the Freedom platform
compatibility header J3, enable the protection diode D9 by opening the
J26 shorting header.

FRDM-K28F hardware description
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Figure 3. Power supply schematic

FRDM-K28F hardware description
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Table 2. FRDM-K28F power supplies
Power supply
name
Description
Notes
P5-9V_VIN
Power supply from the VIN pin of the I/O
headers (J3 pin 16). Sources the main 3.3 V
voltage regulator and the optional 5 V regulator
at J25. A Schottky diode provides the
back-drive protection.
—
P3V3_VREG
Regulated 3.3 V supply. Sources power to the
P3V3 supply rail. A back-drive protection
Schottky diode (D9) is provided to enable an
external 2.7 V–3.3 V supply connection at the
J3 header P3V3 pins.
Open J26 (shorted on the bottom of the board)
if the J3 header P3V3 pins are used to supply
an alternate voltage from the on-board 3.3 V
supply.
VDD_K28F
K28F MCU voltage supply. Select the 3.3 V or
1.8 V regulator options at header J20, or the
2.7 V–3.3 V P3V3 inputs on the J3 header.
Header J18 provides a convenient means for
energy consumption measurements.
The IS42SM16800H-6BLI SDRAM is a 3.3 V
component. Open J10 (shorted on the bottom
of the board) if the VDD_K28F node is less
than 2.7 V.
VDDIO_E_1V8
K28F VDDIO_E MCU voltage supply. Header
J15 provides a convenient means for energy
consumption measurements.
The MT25QU256ABA1EW7-0SIT QSPI flash
is a 1.8 V component. Open J16 (shorted on
the bottom of the board) if the VDDIO_E_1V8
node is ever raised above 1.8 V.
VDDCORE_1V2
K28F VDD_CORE MCU voltage supply.
Header J22 provides a convenient means for
energy consumption measurements.
—
P3V3
Main supply for the 3 V MCU VDD and
peripheral functions. Supplies nominal 3 V at
the J3 header P3V3 nodes. Sourced from the
P3V3_VREG or P3V3 inputs on the J3 I/O
header.
When the J3 P3V3 inputs are used, the voltage
must be in the 2.7 V–3.3V range. See the
VDD_K28F note.
P1V8
Power supply for the 1.8 V MCU VDDIO_E
pins and the QSPI peripheral. P1V8 can be
selected as the MCU VDD source at header
J20.
See the VDD_K28F note if P1V8 is selected as
the source at header J20.
VDD
Supply the voltage for the MCU and many
board functions. Select the 3.3 V or 1.8 V
regulator options on header J20, or the P3V3
inputs on the J3 header.
When the J3 P3V3 inputs are used, the voltage
must be in the 2.7 V–3.3 V range. See the
VDD_K28F note.
P3V3_SDA
OpenSDA v2.2 circuit 3.3 V supply generated
on the K20DX from the USB cable VBUS
signal.
—
P5V
Nominal 5 V supplied to the I/O headers (J3
pin 10).
—
3.2. Serial and Debug Adapter version 2 (OpenSDA v2.2)
OpenSDA v2.2 is a serial and debug adapter circuit which includes open-source hardware design,
open-source bootloader, and debug interface software. It bridges the serial and debug communications
between the USB host and the embedded target processor, as shown in the following figure. The
hardware circuit is based on the Kinetis K20 family MCU with 128 KB of embedded flash and an
integrated USB controller. OpenSDA v2.2 is pre-loaded with the CMSIS-DAP bootloader (an open-
source MSD bootloader), and the DAP-Link interface firmware which provides the MSD flash

FRDM-K28F hardware description
Freedom Board for Kinetis K28F (FRDM-K28F), User's Guide, Rev. 0, 04/2017
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programming interface, virtual serial port interface, and CMSIS-DAP debug protocol interface. For
more information about the OpenSDA v2.2 software, see mbed.org and github.com/mbedmicro/CMSIS-
DAP.
OpenSDAv2
OpenSDA MCU
K20DX128Vxx5
MSD Bootloader
OpenSDAv2
Application
UART TX/RX
GPIO
Serial Terminal
File System
SWD/JTAG
LED PWM
USB Host
IDE GPIO/ADC
SPI, GPIO
USB
Target
Processor
nRESET
UART RX/TX
Figure 4. OpenSDA high-level block diagram
OpenSDA v2.2 is managed by the Kinetis K20 MCU built upon the ARM Cortex-M4 core.
The OpenSDA v2.2 circuit includes a status LED (D3) and a push-button (SW1). The push-button
asserts the reset signal to the K28F target MCU. It can be also used to place the OpenSDA v2.2 circuit
into the bootloader mode. The SPI and GPIO signals provide an interface to either the SWD debug port
or the K20. Additionally, signal connections are available to implement the UART serial channel. The
OpenSDA v2.2 circuit receives power when the USB connector J6 is plugged into a USB host.
3.2.1. Debug interface
Signals with the UART and GPIO capability are used to connect directly to the SWD of the K28F.
These signals are also brought out to the standard 10-pin (0.05”) Cortex debug connector (J23). It is
possible to isolate the K28F MCU from the OpenSDA v2.2 circuit and use J23 to connect to an
off-board MCU. To do this, cut the trace on the bottom side of the PCB that connects the J17 pin 2 to the
J23 pin 4. This disconnects the SWD_CLK pin from the K28F so that it does not interfere with the
communication to an off-board MCU connected to J17.

MCU
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NXP Semiconductors 9
Figure 5. SWD debug connector
The J23 header is populated by default. A mating cable (such as the Samtec FFSD IDC cable) can then
be used to connect the OpenSDA v2.2 of the FRDM-K28F to an off-board SWD connector.
3.2.2. Virtual serial port
A serial port connection is available between the OpenSDA v2.2 MCU and pins PTC24 and PTC25 of
the K28 MCU.
4.MCU
FRDM-K28F features the MK28FN2M0VMI15 MCU. This 150 MHz MCU is a part of the Kinetis K2x
family and it is implemented in the 169 MAPBGA and 210 WLCSP (K28 only) packages. The
FRDM-K28F board also supports the K27 and K28 MCUs. The following table describes some of the
features of the MK28FN2M0VMI15 MCU that is populated on this board.

Clocking
Freedom Board for Kinetis K28F (FRDM-K28F), User's Guide, Rev. 0, 04/2017
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Table 3. MK28FN2M0VMI15 MCU features
Feature
Description
Performance
•Up to 150 MHz ARM Cortex-M4-based core with DSP instructions and a
single precision floating-point unit.
Memory and memory expansion
•2 MB program flash memory and 1 MB RAM.
•Dual QuadSPI with XIP.
•FlexBus external bus interface and SDRAM controller.
Analog modules
•One 16-bit SAR ADC, two 6-bit DACs, and one 12-bit DAC.
•Two analog comparators (CMP) containing a 6-bit DAC and a
programmable reference input.
•Voltage reference: 1.2 V.
Communication interfaces
•USB high-speed device/host.
•USB full-/low-speed on-the-go controller with the device charge detect
capability.
•Secure Digital Host Controller (SDHC).
•FlexIO.
•Two I2S modules, four SPI modules (SPI3 supports more than 40 Mbit/s),
four I2C modules, and five LPUART modules.
Security
•Hardware random-number generator.
•Supports DES, AES, and SHA accelerator (CAU).
•Cyclic Redundancy Check (CRC).
•Multiple levels of embedded flash security.
Timers
•One 4-channel 32-bit periodic interrupt timer.
•Two 16-bit low-power timer PWM modules.
•Two 8-channel motor-control/general-purpose/PWM timers.
•Two 2-channel quadrature decoder/general-purpose timers.
•Real-time clock with an independent 3.3 V power domain.
•Programmable delay block.
Human machine interface
•Up to 120 general-purpose inputs/outputs.
Operating Characteristics
•Main VDD voltage and flash write voltage range: 1.71 V–3.6 V.
•Temperature range (ambient): -40–105°C.
•Independent VDD_CORE: 1.17 V-1.47 V.
•Independent VDDIO for PORTE (QuadSPI): 1.71 V–3.6 V.
•Independent VBAT (RTC): 1.71 V–3.6 V.
5.Clocking
CAUTION
The resonator is not recommended when the HS USB is used.
The K28F MCU starts up from an internal Digitally-Controlled Oscillator (DCO). Software can enable
the main external oscillator (EXTAL0/XTAL0) if desired. The external oscillator/resonator can range
from 32.768 kHz up to 32 MHz. The default external source for the MCG oscillator inputs (EXTAL) is
the 12 MHz crystal, which is configured to operate in the low-power mode, so the feedback resistor
(R78) is not needed. The 12 MHz reference clock is suitable for both the audio codec and the HS USB
features.