NXP
freescale Kinetis
TWR-K21F120M Quick Start Guide
Low-Power 32-bit ARM® Cortex®-M4 Core-Based MCUs with Floating Point Unit, USB Connectivity and Enhanced Security
Tower System Development Board Platform
Image of the TWR-K21F120M development board, showing its main components and connectors. The NXP logo is displayed in orange and yellow at the top left. To its right, the Freescale Kinetis logo is shown. The main title 'TWR-K21F120M Quick Start Guide' is prominent, followed by a subtitle describing the MCU's capabilities: 'Low-Power 32-bit ARM® Cortex®-M4 Core-Based MCUs with Floating Point Unit, USB Connectivity and Enhanced Security'. Below this, 'Tower System Development Board Platform' is presented. A diagonal orange shape covers the bottom right, overlaying a detailed image of the TWR-K21F120M development board, showing numerous electronic components, connectors, and silkscreen labels.
Get to Know the TWR-K21F120M Board
A detailed diagram of the front side of the TWR-K21F120M board is presented, with various components and connectors labeled. Key labels include: K21 Cortex Debug, VBAT Options, JM60 BDM, JM60 Bootloader Selection, Power/OSJTAG Micro-USB, Regulator Option Selector, RESET, K21 USB Micro OTG, General-Purpose TWRPI Plug-In, Potentiometer, LEDs, Accelerometer, SW3, SW2, Tamper Pins, and USB Option Selector. On the right side of the diagram, the Battery Receptacle and SD Card Receptacle are also indicated.
TWR-K21F120M Freescale Tower System Development Board Platform
The TWR-K21F120M board is designed to work either in standalone mode or as part of the Freescale Tower System, a modular development board platform that enables rapid prototyping and tool re-use through reconfigurable hardware. Begin constructing your Tower System evaluation board platform today by visiting freescale.com/Tower for additional Tower System boards and compatible peripherals.
Features
- MK21FN1M0VMC12 MCU (120 MHz, 1 MB flash, 128 KB RAM, FPU, USB OTG, tamper detection, encryption, low power, 121 MBGA)
- Dual-role USB interface with Micro-AB USB connector
- Onboard open source JTAG (OSJTAG) circuit with virtual serial port
- General-purpose Tower plug-in (TWRPI) socket
- Three-axis accelerometer (MMA8451Q)
- Four user-controlled status LEDs
- Pushbuttons for GPIO interrupts and MCU reset
- Potentiometer, SD card socket and coin cell battery holder
- Independent, battery-operated power supply for real-time clock and tamper detection modules
Step-by-Step Installation Instructions
In this Quick Start Guide, you will learn how to set up the TWR-K21F120M board and run the included demonstration software. For more detailed information, review the user manual at freescale.com/TWR-K21F120M.
Download Software and Tools
Download installation software and documentation under "Jump Start Your Design" at freescale.com/TWR-K21F120M.
Install the Software and Tools
Install the P&E Micro Kinetis Tower toolkit. The toolkit includes the OSJTAG and USB to serial drivers.
Configure the Hardware
Install the included battery into the battery receptacle to power the RTC. Then use the provided USB cable to connect the PC to the Power/OSJTAG USB Micro-B connector (J2). Allow the PC to automatically configure the USB drivers if needed.
Tilt the Board
Tilt the board side to side to see the LEDs on D5, D6, D8 and D9 light up as it is tilted. While the board is held flat, press SW2 and SW3 to toggle LEDs D5 and D9, respectively.
Download the Freescale CodeWarrior IDE and MQX™ RTOS
Download the Freescale CodeWarrior IDE and MQX RTOS by clicking the relevant links at freescale.com/CodeWarrior and freescale.com/MQX.
F120M Jumper Options
The following is a list of all jumper options on the TWR-K21F120M. The default installed jumper settings are indicated in the shaded boxes.
| Jumper | Option | Setting | Description |
|---|---|---|---|
| J6 | JTAG Board Power Selection | ON | Connect OSJTAG 5 V output (P5V_TRG_USB) to JTAG port (supports powering board from JTAG pod supporting 5 V supply output) |
| OFF | Disconnect OSJTAG 5 V output (P5V_TRG_USB) from JTAG port | ||
| J7 | VBAT Power Source | 1-2 | Connect VBAT to onboard 3.3 V or 1.8 V supply |
| 2-3 | Connect VBAT to the higher voltage between MCU supply (MCU_ PWR) or coin cell supply (VBATD) | ||
| J8 | MCU Power Connection | 1-2 | Connect onboard 3.3 V or 1.8 V supply (V_BRD) to MCU VDD |
| 2-3 | Connect K21 USB regulator output to MCU VDD | ||
| J9 | OSJTAG Bootloader Selection | ON | OSJTAG bootloader mode (OSJTAG firmware reprogramming) |
| OFF | Debugger mode | ||
| J10 | General-Purpose TWRPI | ON | Connect onboard 1.8 V or 3.3 V supply (V_BRD) to TWRPI 3 V power (GPT_VBRD) |
| OFF | Disconnect from-board 1.8 V or 3.3 V supply (V_BRD) to TWRPI 3 V power (GPT_VBRD) | ||
| J11 | V_BRD Power Enable | 1-2 | OSJTAG 5 V output (P5V_TRG_USB) connected to onboard regulator input (VREG_IN) |
| 5-6 | VBUS signal on micro-USB connector J19 connects to K21_VREGIN to allow standalone USB operation | ||
| 6-8 | VBUS signal from Tower elevator connector connects to K21_VREGIN to allow USB operation with complete Tower System | ||
| J12 | Potentiometer Connection | ON | Connect potentiometer to ADC0_SE12 |
| OFF | Disconnect potentiometer from ADC0_SE12 | ||
| J13 | GPIO RESET_OUT_B connection | 1-2 | Connect PTA14 to RESET_OUT_B signal |
| 2-3 | Connect PTA17 to RESET_OUT_B signal | ||
| OFF | Leave RESET_OUT_B signal disconnected | ||
| J15 | LED Connections | 1-2 | Connect PTD4 to green LED (D5) |
| 3-4 | Connect PTD5 to yellow LED (D6) | ||
| 5-6 | Connect PTD6 to red LED (D8) | ||
| 7-8 | Connect PTD7 to blue LED (D9) | ||
| OFF | Disconnect PTD[4:7] from associated LED | ||
| J16 | SDHC Card | OFF | 10K pulldown resistor is disconnected from CD/DATA3 line |
| ON | 10K pulldown resistor is connected to CD/DATA3 line to allow card detection | ||
| J17 | V_BRD Power Source (Board Power Selector) | 1-2 | Connect K21 USB regulator output (VOUT_3V3) to onboard supply (V_BRD) |
| 3-5 | Connect 3.3 V onboard regulator output (P3V3) to onboard supply (V_BRD) | ||
| 5-7 | Connect 1.8 V onboard regulator output (P1V8) to onboard supply (V_BRD) | ||
| J18 | Accelerometer IRQ Connection | 1-2 | Connect PTB0 to INT1 pin of accelerometer |
| 3-4 | Connect PTB1to INT2 pin of accelerometer | ||
| OFF | Disconnect PTB0 and/or PTB1 from INT1 and/or INT2 of accelerometer | ||
| J21 | USB ID Connection | ON | Connect PTD7 to USB ID pin |
| OFF | Disconnect PTD7 from USB ID pin | ||
| J22 | USB Power Enable | ON | Connect PTC9 to USB power enable on power switch MIC2026 |
| OFF | Disconnect PTC9 from USB power enable on power switch MIC2026 | ||
| J23 | USB OverCurrent Flag | ON | Connect PTC8 to overcurrent flag on power switch MIC2026 |
| OFF | Disconnect PTC8 from overcurrent flag on power switch MIC2026 | ||
| J24 | USB Connection | 1-2 | USB micro J19 |
| 2-3 | USB mini J14 on TWR-SER | ||
| JP1 | Tamper Connections | 2-3 | JP1-1 through JP1-6 are connected to the MCU Tamper pins TAMPER0 through TAMPER5, respectively |
Get Started
Download installation software and documentation under "Jump Start Your Design" at freescale.com/TWR-K21F120M.
Visit freescale.com/TWR-K21F120M, freescale.com/K20 or freescale.com/Kinetis for more information on the TWR-K21F board.
Support
Visit freescale.com/support for a list of phone numbers within your region.
Warranty
Visit freescale.com/warranty for complete warranty information.
For more information, visit freescale.com/Tower
Join the online Tower community at towergeeks.org
