ARM Technical Support Knowledge Articles


Applies to: RTX51 Real-time Kernel


Information in this article applies to:


While debugging an RTX51 application on a Cypress EZ-USB FX or FX2 board using MON51, clicking the Halt button gives the error:

  Failed to stop application!

Setting breakpoints and single-stepping work OK and the Stop Program Execution with Serial Interrupt checkbox is checked. What could be wrong?


RTX51 disables serial interrupts by default. With serial interrupts disabled and no breakpoints set, MON51 cannot gain control of the target board once it starts running.


Configure RTX51 to enable the appropriate serial interrupt by setting the correct initialization value for ?RTX_IE_INIT in the RTXSETUP.INC file. Cypress FX and FX2 boards use the standard 8051 serial interrupt for SIO-0. To enable the this serial interrupt (bit 4 in IE) use the following value:

  ?RTX_IE_INIT  EQU  10H  ; Enable 8051 serial interrupts

To debug through SIO-1 on Cypress FX and FX2 boards, enable SIO-1 interrupts (bit 6 in IE) as follows:

  ?RTX_IE_INIT  EQU  40H  ; Enable Cypress FX/FX2 SIO-1 interrupts

Other microcontrollers might use this bit for a second serial port also. Check the manufacturer's data sheet for your microcontroller to be sure.


Article last edited on: 2007-01-16 10:12:37

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