General
Review and verify the following for
the custom schematic design:
- Reviewed above "Common checklist for all sections" section of the
user's guide.
- Connection of JTAG interface
signals.
- Connection of the required pulls.
- JTAG interface signals IO compatibility.
- Fail-safe operation of the JTAG interface signals.
Schematic Review
Follow the below list for the custom schematic
design:
- Connection of JTAG interface signals and EMU0, EMU1 signals to the JTAG
interface connector.
- Connection of supply voltage to the JTAG connector including filter
capacitor (the recommendation is to connect the voltage source that connects
to VDDSHV_MCU).
- Connection of the recommended pullup and pulldown as per the pin
connectivity requirements near to the processor JTAG interface pins.
- Pullup and pulldown values used (recommend value is 10kΩ).
- JTAG interface signals IO compatibility (IO supply referenced to (powered
by) VDDSHV_MCU).
- Fail-safe operation of the JTAG interface signals. No JTAG inputs are
available when the processor supplies are off.
Additional
- The recommendation is to include (implement) at
least a minimal JTAG signals on the custom board designs, connected to test
points or header for debugging early prototypes. The minimum recommended JTAG
signals are TCK, TMS, TDI, TDO, TRSTn and EMU0, EMU1. If required, the
recommendation is to delete JTAG routes and component footprints (except the
pulldown on TRSTn and the pullups on TMS and TCK) in the production version of
the board.
- When trace is implemented, the TRC_DATAn signals
are recommended to be connected to the emulation connector. All TRC_DATAn
signals are pin-muxed with other signals. If the trace connections are
implemented, the recommendation is to not use other muxed functions. The
recommendation is to use short and slew matched traces (routes) for TRC_DATAn
signals. Trace signals are referenced to (powered by) a different power domain
and can be operating at a different voltage compared to JTAG signals.
- The recommendation is to add provision for
external ESD protection. The external ESD protection can be populated when JTAG
interface is used.
- The recommendation is to verify fail-safe
operation when using JTAG interface. Applying an external input signal to the
processor JTAG inputs before processor supply ramps can cause voltage feed and
can affect the custom board functions.