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Hi, At the moment, i got a uCOS-II-based-application running in "Flash Application" target (Codewarrior). I want to run it in "Banked Flash" mode. As you can think, some problems occur with assembly routines. After a while reading datasheets i resolve some problems (e.g. JSR-RTS replaced by CALL-RTC instructions) but some stay. Routine example : OSStartHighRdy: call OSTaskSwHook, PAGE(OSTaskSwHook) ;Invoke user defined context switch hook inc OSRunning ;Indicate that we are multitasking ldx OSTCBHighRdy ;Point to TCB of highest priority task ready to run lds 0,x ;Load SP into 68HC12 rti ;Run task when i use this, the value of PC register in the task stack is wrong ;1) The stack frame is assumed to look as follows: ; ; OSTCBHighRdy->OSTCBStkPtr + 0 --> CCR ; + 1 B ; + 2 A ; + 3 X (H) ; + 4 X (L) ; + 5 Y (H) ; + 6 Y (L) ; + 7 PC(H) ; + 8 PC(L) when i debug this, i obtain : - at RTI instruction : SP = 0x10F2 where i can find the highest priority task stack so no problem, so SP + 0 --> 0x80 SP + 1 --> 0xBB SP + 2 --> 0xAA SP + 3 --> 0x11 SP + 4 --> 0x11 SP + 5 --> 0x22 SP + 6 --> 0x22 SP + 7 --> 0xA0 SP + 8 --> 0x00 so after the RTI, PC will point on 0xA000 and here there is an error, there's nothing at this address and highest priority task is at 0xC4A0, so if i change it by edit mode in the memory window of hiwave it works, the RTI returns good maybe its a problem with OS initialization but init code is exactly the same C code as my old "Flash Application" which works fine and C compiler should make the change between the two target. Please, help a young french student to get his OS working :) Need more details ? Thank you, Don` (sorry for my english) |
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9S12DP256 codewarrior uCOS-II banked flash
Started by ●December 7, 2003
Reply by ●December 8, 20032003-12-08
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Don, When you run your code in paged mode, the address window $8000 - $BFFF is used to access various pages of code. When your code manipulates the value of the PPAGE register (using the CALL and RTC instructions) it places different code chunks, each 16K of size, into the $8000 - $BFFF page. You should therefore assume that for all any jump to code in this range (like the attempt to change task to address $A000 for example in your case), you will need to specify both the PC and PPAGE. Thus, before the RTI I think you need to also set the PPAGE to the correct value and then your task-switching code may work. Alternatively, you need to make sure the tasks you call after the RTI are in non-paged Flash. Please also note that all the interrupt routines are also usually placed in non-paged Flash at $C000 - $FEFF or at $4000 - $7FFF. The reason is that an interrupt can occur while executing code from any code-page. When an interrupt occurs the PC registers are stored to the stack, but PPAGE is not. Also the RTI instruction doesn't restore PPAGE from the stack. Hope this helps, Doron Nohau Corporation HC12 In-Circuit Emulators www.nohau.com/emul12pc.html At 14:51 07/12/2003 +0000, you wrote: >Hi, > >At the moment, i got a uCOS-II-based-application running in "Flash >Application" target (Codewarrior). I want to run it in "Banked Flash" >mode. >As you can think, some problems occur with assembly routines. After a >while reading datasheets i resolve some problems (e.g. JSR-RTS >replaced by CALL-RTC instructions) but some stay. >Routine example : > >OSStartHighRdy: > call OSTaskSwHook, PAGE(OSTaskSwHook) ;Invoke user defined context > switch hook > inc OSRunning ;Indicate that we are multitasking > ldx OSTCBHighRdy ;Point to TCB of highest priority task ready to run > lds 0,x ;Load SP into 68HC12 > rti ;Run task > >when i use this, the value of PC register in the task stack is wrong > >;1) The stack frame is assumed to look as follows: >; >; OSTCBHighRdy->OSTCBStkPtr + 0 --> CCR >; + 1 B >; + 2 A >; + 3 X (H) >; + 4 X (L) >; + 5 Y (H) >; + 6 Y (L) >; + 7 PC(H) >; + 8 PC(L) > >when i debug this, i obtain : >- at RTI instruction : SP = 0x10F2 where i can find the highest >priority task stack so no problem, so >SP + 0 --> 0x80 >SP + 1 --> 0xBB >SP + 2 --> 0xAA >SP + 3 --> 0x11 >SP + 4 --> 0x11 >SP + 5 --> 0x22 >SP + 6 --> 0x22 >SP + 7 --> 0xA0 >SP + 8 --> 0x00 > >so after the RTI, PC will point on 0xA000 and here there is an error, >there's nothing at this address and highest priority task is at >0xC4A0, so if i change it by edit mode in the memory window of hiwave >it works, the RTI returns good > >maybe its a problem with OS initialization but init code is exactly >the same C code as my old "Flash Application" which works fine and C >compiler should make the change between the two target. > >Please, help a young french student to get his OS working :) >Need more details ? > >Thank you, >Don` >(sorry for my english) |
