A "debug port fail" error message after a SYStem.Up or SYStem.Mode Attach could have one of the following reasons:
- The selected debug port type (JTAG / LPD4 / LPD1) does not match the Option Bytes (G3-core variants). Please try different debug port types using the command SYStem.CONFIG DEBUGPORTTYPE
- RDY-line not connected. Please try to set SYStem.Option.RDYLINE OFF
- The debug signals have a bad quality e.g. reflections on TCK line. Please check the debug signals, especially TCK with a scope. A serial termination at TCK (e.g. 50..100Ohm) between target and debugger may solve the problem in such cases. Check moreover if the FLMD0 signal is correctly connected.
- JTAG clock is too high (JTAG mode only). Try to increase the JTAG clock using the command SYStem.JtagClock
- The RESET signal of the CPU is not properly connected. Check the voltage level with an oscilloscope. The RESET signal should toggle at SYStem.Up. Check additionally if the CPU is permanently in reset.
- The problem may be caused in some cases by the target application: when a debug tool tries to connect to the CPU, the application code is already running (not for G4-core variants). Application code may disturb the debug-connection process. A workaround is to patch a jump to the same address at the reset vector.
- Debug interface is locked
- ID-Code-Protection Unit is locked (G3K-core variants only)
- OSCCLOCK and CORECLOCK don't match the target oscillator frequency and CPU Core-Clock (UART mode)
- Wrong baud rate value. Try different values using the command SYStem.BAUDRATE
Please use the AutoSetup dialog to connect to the target by selecting the menu RH850 > Auto Setup or calling the script ~~/demo/rh850/flash/rh850_autosetup.cmm
Please refer for more information to the RH850 Debugger and Trace manual.