Microsemi IGLOO2 - Device Programming; JTAG Programming; Table 15 JTAG Pins

Board Design Guidelines for SmartFusion2 SoC and IGLOO2 FPGAs
AC393 Application Note Revision 14.0 23
2.7 Device Programming
The SmartFusion2/IGLOO2 device can be programmed via one of two dedicated interfaces: JTAG or
SPI. These two interfaces support the following programming modes:
• Auto-programming (master) mode
• In-system programming:
• JTAG programming mode
• SPI Slave programming mode
• In-application update:
• Cortex-M3 update mode (only for SmartFusion2 devices)
• Auto update mode
For detailed information about programming the device, see the UG0451: IGLOO2 and SmartFusion2
Programming User Guide.
2.7.1 JTAG Programming
The JTAG interface is used for device programming and testing or for debugging the Cortex-M3
firmware, as listed in the following table. These functions are enabled depending on the state of the
JTAGSEL input. When the device reset is asserted, JTAG I/O are still enabled but cannot be used as the
TAP controller is in reset. JTAG I/O are powered by VDDI in the I/O bank where they reside. JTAG pins
must be connected as shown in the following figure.
Table 15 • JTAG Pins
Pin Names Direction Weak Pull-up Description
JTAG_TMS Input Yes JTAG test mode select.
JTAG_TRSTB Input Yes JTAG test reset. Must be held low during device operation.
JTAG_TDI Input Yes JTAG test data in.
JTAG_TCK Input No JTAG test clock. Microsemi recommends that TCK be tied
to VSS or VDDI through a resistor on the board when
unused per IEEE 1532 requirements. This prevents totem-
pole current on the input buffer.
JTAG_TDO Output No JTAG test data out.
JTAGSEL Input Connect the JTAGSEL pin
to an external pull-up
resistor. The default
configuration should
enable the FPGA fabric
TAP.
JTAG controller selection. Depending on the state of the
JTAGSEL pin, an external JTAG controller connects to
either the FPGA fabric TAP (high) or the Cortex-M3 JTAG
debug interface (low).
For SmartFusion2-based designs, this signal must be held
high or low through jumper settings.
For IGLOO2-based designs, this signal must be held high
through a pull-up resistor.