Datasheet

FRDM-K64F Hardware Description
FRDM-K64F Freedom Module User’s Guide, User's Guide, Rev. 1, 08/2016
6 NXP Semiconductors
3.2. Serial and Debug Adapter version 2 (OpenSDAv2)
OpenSDAv2 is a serial and debug adapter circuit which includes an open-source hardware design, an
open-source bootloader, and debug interface software. It bridges serial and debug communications
between a USB host and an embedded target processor as shown in Figure 4. The hardware circuit is
based on an NXP Kinetis K20 family microcontroller (MCU) with 128 KB of embedded flash and an
integrated USB controller. OpenSDAv2 comes preloaded with the CMSIS-DAP bootloader – an open-
source mass storage device (MSD) bootloader and the CMSIS-DAP Interface firmware (aka mbed
interface), which provides a MSD flash programming interface, a virtual serial port interface, and a
CMSIS-DAP debug protocol interface. For more information on the OpenSDAv2 software, see
mbed.org and https://github.com/mbedmicro/CMSIS-DAP.
Figure 4. OpenSDAv2 high-level block diagram
OpenSDAv2 is managed by a Kinetis K20 MCU built on the ARM Cortex-M4 core. The OpenSDAv2
circuit includes a status LED (D2) and a pushbutton (SW1). The pushbutton asserts the Reset signal to
the K64 target MCU. It can also be used to place the OpenSDAv2 circuit into bootloader mode. SPI and
GPIO signals provide an interface to either the SWD debug port or the K20. Additionally, signal
connections are available to implement a UART serial channel. The OpenSDAv2 circuit receives power
when the USB connector J26 is plugged into a USB host.
Debug interface
Signals with SPI and GPIO capability are used to connect directly to the SWD of K64. These signals are
also brought out to a standard 10-pin (0.05”) Cortex debug connector (J9). It is possible to isolate the
K64 MCU from the OpenSDAv2 circuit and use J9 to connect to an offboard MCU. To accomplish this,
cut the trace on the bottom side of the PCB that connects J11 pin 2 to J9 pin 4. This will disconnect the
SWD_CLK pin to the K64 so that it will not interfere with the communications to an offboard MCU
connected to J11.