USB-Serial as JTAG Master - KBA224254

Version 3

    Author: HPPC          Version: **

     

    This article describes the procedure to exercise the JTAG master capability of a USB-Serial device (CY7C65215-32LTXI) on the CYUSBS236 USB-Serial Development Kit.

     

    The USB-Serial device can act as a JTAG master at a rate of 400 kHz. The serial communication block 1 (SCB1) can be configured as a JTAG interface (vendor class) using the USB-Serial Configuration Utility.

     

    Pin mapping on the USB-Serial device for the JTAG signals is as follows:

     

    Table 1: JTAG Signals on the USB-Serial Device

     

     

    JTAG Signal

    USB Serial Pins

    TDI

    SCB1_1 (Pin 6)

    TDO

    SCB1_0 (Pin 5)

    TMS

    SCB1_2 (Pin 7)

    TCK

    SCB1_3 (Pin 8)

    TRST_N

    SCB1_4 (Pin 9)

     

    Figure 1: CYUSBS236 USB-Serial Development Kit

    Untitled.png

     

    The JTAG functionality of USB-Serial (CY7C65215) can be demonstrated using the CYUSBS236 USB-Serial Development Kit and EZ-USB FX3 (CYUSB3014), where USB-Serial acts as JTAG master and EZ-USB FX3 acts as JTAG slave. In this setup, USB-Serial is used as a USB-JTAG interface and can debug the EZ-USB FX3 firmware. The hardware connections need to be wired as follows:

     

    Table 2: CYUSBS236 DVK to FX3 Connections

     

    USB-Serial DVK

    FX3

    Jumper

    Pin

    Pin

    J25

    1

    E7 (TDI)

    J24

    1

    C10 (TDO)

    J26

    1

    E8 (TMS)

    J27

    1

    F6 (TCK)

    J23

    P1.6

    B11 (TRST_N)

    J23

    16 (GND)

    GND

     

    Test Setup

    1. Install the EZ-USB FX3 Software Development Kit (SDK).

    2.  Connect the EZ-USB FX3 and USB-Serial device to the PC, and bind both to the corresponding drivers. The driver binding procedure for USB-Serial is available at: <Install directory>\CYUSBS236 DVK\1.0\documentation\Cypress USB-Serial Driver Installation Guide.pdf.

    3. Configure the USB-Serial device as a JTAG device using the USB-Serial Configuration Utility.

    4. The instructions for debugging the EZ-USB FX3 firmware are available in the EZ-USB FX3 SDK installation directory:
    <Install directory>\EZ-USB FX3 SDK\1.3\doc\firmware\EzUsbSuite_UG.pdf.

    5. The EZ-USB FX3 SDK uses the Eclipse™ IDE to build the firmware and launch the standard GNU debugger GDB used by the OpenOCD server for debugging purpose.

     

    Notes:

    • On Windows 32-bit platforms, the default <Install directory> is C:\Program files\Cypress; on Windows 64-bit platforms, it is C:\Program files(X86)\Cypress.
    • A custom firmware is required to implement UART communication on SCB0 while SCB1 is being used for JTAG communication.