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.
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).
Note:
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 15-2: Bank Usage of IOCSR Scan Chains
The following table shows the mapping of the IOCSR scan chains to the I/O banks.
Usage
HPS I/O Bank
Bank Type
IOCSR Scan Chain
EMAC
I/O bank 7D and I/O bank
7E
VIO
0
SD/MMC, NAND, and
quad SPI
I/O bank 7B and I/O bank
7C
VIO
1
Trace, SPI, UART, I2C,
and CAN
I/O bank 7A
VIO
2
SDRAM DDR
I/O bank 6
HIO
3
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.
CONFIG_IO
mode is commonly used to configure the I/O pin properties prior to performing
boundary scan testing.
Note:
Related Information
•
Configuring HPS I/O Scan Chains
on page 15-5
•
Communicating with the JTAG TAP Controller
on page 15-6
Scan Manager
Altera Corporation
cv_54015
Scan Manager Block Diagram and System Integration
15-4
2013.12.30