1. Lab III Real-Time Embedded Operating System for a SoC System

3. Startup Flow Chat Reset Building Exception Handler Initiation Stack Pointer for Exception mode and SPSR Execution C_function initialization Stack LDR r7, #RAMBased MRSr4, cpsr ORRr4, r4, #NoIRQ ORRr4, r4, #NoFIQ BICr4, r4, #ModeMask Clear Mode MOVr2, #User32Mode ;-------------------------------------------------- ORRr5, r4, #IRQ32Mode MSRcpsr_c, r5 MSRspsr_c, r2 MOVsp, r7; Initial IRQ stack pointer... SUBr7, r7, #IRQStackSize....;;Set SVC Mode Stack pointer ;;Set User Mode Stack pointer Set INTMSK ;Disable IRQ Clear INTPND

4. ARM Exception ARM Exception Events ARM Exception Events

5. Install an Exception Handler: Method Vector_Init_Block b Reset_Addr b Undefined_Addr b SWI_Addr b Prefetch_Addr b Abort_Addr NOP ;Reserved vector b IRQ_Addr b FIQ_Addr Reset_Addr … Undefined_Addr … B.For loop SWI_Addr … Prefetch_Addr … B. For loop Abort_Addr … IRQ_Addr … FIQ_Addr …

6. Install an Exception Handler: Method Vector_Init_Block LDR PC, Reset_Addr LDR PC, Undefined_Addr LDR PC, SWI_Addr LDR PC, Prefetch_Addr LDR PC, Abort_Addr NOP ;Reserved vector LDR PC, IRQ_Addr LDR PC, FIQ_Addr Reset_Addr DCD Start_Boot Undefined_Addr DCD Undefined_Handler SWI_Addr DCD SWI_Handler Prefetch_Addr DCD Prefetch_Handler Abort_Addr DCD Abort_Handler DCD 0 ;Reserved vector IRQ_Addr DCD IRQ_Handler FIQ_Addr DCD FIQ_Handle Start_Boot LDR … Undefined_Handler B. (for loop)

7. SWI Exception and Handler Top-Level SWI Handlers The SWI number is stored in bits 0-23 of the instruction Save all other r0~r12 and lr to the stack Calculate the SWI number Jump Your Handler Return void __swi(n) SWI_Name(void); for C Call

8. SWI_Handler Flow SWI_Handler ; top-level handler STMFD sp!,{r0-r12,lr} ; Store registers. LDR r0,[lr,#-4] ; Calculate address of SWI instruction ; and load it into r0. BIC r0,r0,#0xff000000 ; Mask off top 8 bits of instruction ;to give SWI number. ; ; Use value in r0 to determine which SWI routine to execute. ; BNE after ; Branch You Handler ; ; Branch your Handler LDMFD sp!, {r0-r12,pc}^ ; Restore registers and return

9. IRQ Handler Flow IRQ_Handler; top-level handler STMFD sp!,{r0-r12,lr} ; Store registers. BL ISR_IRQ LDMFD sp!, {r0-r12,pc} ; Restore registers and return SUBS pc, lr, #4

10. S3C4510B Interrupt Sources

11. Samsung S3C4510B Interrupt Controller Five special registers used to control the interrupt generation and handling Interrupt mode register Defines the interrupt mode, IRQ(0) or FIQ(1), for each interrupt source. Interrupt pending register Indicates that an interrupt request is pending Interrupt mask register The current interrupt is disabled if the corresponding mask bit is "1 “ If the global mask bit (bit 21) is set to "1", no interrupts are serviced. Interrupt priority registers Interrupt offset register Determine the highest priority among the pending interrupts.

12. Interrupt Mask Register (INTMSK) If global mask bit (bit 21) is 1, no interrupts are serviced If bit is 1, the interrupt is not serviced by the CPU when the corresponding interrupt is generated

13. Interrupt pending register Each of the 21 bits corresponds to an interrupt source Each of the 21 bits corresponds to an interrupt source The service routine must then clear the pending condition by writing a 1 to the appropriate pending bit at start. #define Clear_PendingBit(n) INTPND_REG=(1<<n) #define Clear_PendingBit(n) INTPND_REG=(1<<n)

14. Interrupt offset register Contains the interrupt offset address of the interrupt Hold the highest priority among the pending interrupts Hold the highest priority among the pending interrupts The content of the interrupt offset address is "bit position value of the interrupt source << 2 “ You can read this register to get the IRQNumber #define INTOFFSET REG32(SYS_BASE+0x4024) int currentIRQnumber=INTOFFSET >> 2;

15. 32-BIT TIMERS INTERVAL MODE OPERATION INTERVAL MODE OPERATION fTOUT = fMCLK / Timer data value Example. 2 = 50 MHz /25 MHz 25MHz=2FAF080 TOGGLE MODE OPERATION fTOUT = fMCLK / (2 * Timer data value)

16. TIMER MODE REGISTER The timer mode register, TMOD, is used to control the operation of the two 32-bit timers [0] Timer 0 enable (TE0) 0 = Disable timer 0 1 = Enable timer 0 [1] Timer 0 mode selection (TMD0) 0 = Interval mode 1 = Toggle mode [2] Timer 0 initial TOUT0 value (TCLR0) 0 = Initial TOUT0 is 0 in toggle mode 1 = Initial TOUT0 is 1 in toggle mode #define TMOD REG32(SYS_BASE+0x6000)

17. TIMER DATA REGISTERS #define TDATA0 REG32(SYS_BASE+0x6004) #define TDATA0 REG32(SYS_BASE+0x6004)

18. About CodeWarrior Configure

19. Reference Samsung S3C4510B User ’ s Manual Samsung S3C4510B User ’ s Manual http://www.samsung.com/Products/Semiconducto r/SystemLSI/Networks/PersonalNTASSP/Commu nicationProcessor/S3C4510B/S3C4510B.htm http://www.samsung.com/Products/Semiconducto r/SystemLSI/Networks/PersonalNTASSP/Commu nicationProcessor/S3C4510B/S3C4510B.htm Chapter 7 ARM Exceptions ARM 原理與實作 – 以網路 SOC 為例