Arria V Hard Processor System Technical Reference Manual

ID 683011
Date 12/02/2022
Public
Document Table of Contents

7.2.2. Arm* JTAG-AP Scan Chains

The Arm* JTAG-AP supports up to eight scan chains. The scan manager uses only scan chains 0, 1, 2, 3, and 7.

Scan chain 7 of the JTAG-AP connects to FPGA JTAG TAP controller. When the system manager undergoes a cold reset, this connection is disabled and the FPGA JTAG pins are connected to the FPGA JTAG TAP controller. You can configure the system manager to enable the connection, which allows software running on the HPS to communicate with the FPGA JTAG TAP controller. In this case, software can send JTAG commands (such as the SHIFT_EDERROR_REG JTAG instruction) to the FPGA JTAG and get responses to determine details about CRC errors detected by the control block when the FPGA fabric is in user mode. Through the FPGA manager, software can determine that a CRC error was detected. For more information about the TAP controller, refer to the Communicating with the JTAG TAP Controller section of this chapter.

Scan chains 0 to 3 of the JTAG-AP connect to the configuration information in the HPS I/O scan chain banks through the I/O configuration shift register (IOCSR) multiplexer. For more information, refer to the Configuring HPS I/O Scan Chains section of this chapter.

Note: The I/O scan chains do not use the JTAG protocol. The scan manager uses the JTAG-AP as a parallel-to-serial converter for the I/O scan chains. The I/O scan chains are connected only to the serial output data (TDI JTAG signal) and serial clock (TCK JTAG signal).

The HPS I/O pins are divided into six banks. Each I/O bank is either a vertical (VIO) or horizontal (HIO) I/O, based on its location on the die.

Table 29.  Bank Usage of IOCSR Scan ChainsThe following table shows the mapping of the IOCSR scan chains to the I/O banks.

IOCSR Scan Chain

Bank Type

HPS I/O Bank

Usage

0

VIO

I/O bank 7D and I/O bank 7E

EMAC

1

VIO

I/O bank 7B and I/O bank 7C

SD/MMC, NAND, and quad SPI

2

VIO

I/O bank 7A

Trace, SPI, UART, and I2C

3

HIO

I/O bank 6

SDRAM DDR

When the FPGA JTAG TAP controller is in CONFIG_IO mode, the controller can override the scan manager JTAG-AP and configure the HPS I/O pins. For more information, refer to the Configuring HPS I/O Scan Chains section of this chapter.

Note: CONFIG_IO mode is commonly used to configure the I/O pin properties prior to performing boundary scan testing.
Note: The HPS JTAG pins and the following HPS I/O pins do not support boundary scan tests (BST):
  • DDR SDRAM
  • OSC1/2
  • Warm/Cold reset
To perform boundary scan testing on HPS I/O pins, use the FPGA JTAG.