Interrupt system f28x

Chapter 4 : Interrupt
System C28x

Digital Signal Controller
TMS320F2812

Technology beyond the Dreams™ Copyright © 2006 Pantech Solutions Pvt

RS
C28x Core Interrupt Lines
NMI
INT1
INT2
• 2 non-maskable interrupts (RS,
INT3
INT4
“selectable” NMI)
C28x
INT5
• 14 maskable interrupts (INT1 –
INT6
CORE INT7
INT14)
INT8
INT9
INT10
INT11
INT12
INT13
INT14

C28x Reset Sources

C28x Core
Watchdog Timer
RS
RS pin active

To RS pin


Register Bits Initialized at Reset
Register bits defined by reset
PC 0x3F FFC0 PC loaded with reset vector
ACC 0x0000 0000 Accumulator cleared
XAR0 - XAR7 0x0000 0000 Auxiliary Registers
DP 0x0000 Data Page pointer points to page 0
P 0x0000 0000 P register cleared
XT 0x0000 0000 XT register cleared
SP 0x0400 Stack Pointer to address 0400
RPC 0x00 0000 Return Program Counter cleared
IFR 0x0000 no pending interrupts
IER 0x0000 maskable interrupts disabled
DBGIER 0x0000 debug interrupts disabled


Control Bits Initialized at Reset
Status Register 0 (ST0)
SXM = 0 Sign extension off
OVM = 0 Overflow mode off N=0 negative flag
TC = 0 test/control flag V=0 overflow bit
C=0 carry bit PM = 000 set to left-shift-by-1
Z=0 zero flag OVC = 00 0000 overflow counter
Status Register 1 (ST1)
INTM = 1 Disable all maskable interrupts - global
DBGM = 1 Emulation access/events disabled
PAGE0 = 0 Stack addressing mode enabled/Direct addressing disabled
VMAP = 1 Interrupt vectors mapped to PM 0x3F FFC0 – 0x3F FFFF
SPA = 0 stack pointer even address alignment status bit
LOOP = 0 Loop instruction status bit
EALLOW = 0 emulation access enable bit
IDLESTAT = 0 Idle instruction status bit
AMODE = 0 C27x/C28x addressing mode
OBJMODE = 0 C27x object mode
M0M1MAP = 1 mapping mode bit
XF = 0 XF status bit
ARP = 0 ARP points to AR0

Reset – Bootloader
XMPNMC=1

Reset (microprocessor mode)
Reset vector fetched
OBJMODE=0 AMODE=0 from XINTF zone 7
ENPIE=0 VMAP=1 0x3F FFC0
M0M1MAP=1

XMPNMC=0
(microcomputer mode)
Reset vector fetched
from boot ROM Boot determined by
state of GPIO pins
0x3F FFC0

Notes: Execution Bootloading
Entry Point Routines
F2810 XMPNMC tied low internal to device
FLASH SPI
XMPNMC refers to input signal
H0 SARAM SCI-A
MP/MC is status bit in XINTFCNF2 register OTP Parallel load
XMPNMC only sampled at reset


Bootloader Options
GPIO pins
F4 F12 F3 F2
1 x x x jump to FLASH address 0x3F 7FF6 *
0 0 1 0 jump to H0 SARAM address 0x3F 8000 *
0 0 0 1 jump to OTP address 0x3D 7800 *
0 1 x x bootload external EEPROM to on-chip memory via SPI port
0 0 1 1 bootload code to on-chip memory via SCI-A port
0 0 0 0 bootload code to on-chip memory via GPIO port B (parallel)

* Boot ROM software configures the device for C28x mode before jump


Reset Code Flow - Summary
0x3D 7800
OTP (2K)
0x3D 8000
FLASH (128K)
0x3F 7FF6
0x3F 8000 H0 SARAM (8K)

Execution Entry
0x3F F000 Boot ROM (4K) Point Determined
Boot Code By GPIO Pins
0x3F FC00
• •
• •

BROM vector (32)
RESET 0x3F FFC0 0x3F FC00 Bootloading
Routines
(SPI, SCI-A,
Parallel Load)


Internal Sources
Interrupt Sources
TINT2
TINT1 C28x CORE
TINT0 RS
NMI
EV and Non-EV PIE
Peripherals INT1
(Peripheral
(EV, ADC, SPI, Interrupt INT2
SCI, McBSP, CAN) Expansion) INT3
•
External Sources •
•
INT12
XINT1
INT13
XINT2
INT14
PDPINTx
RS
XNMI_XINT13

Maskable Interrupt Processing Conceptual Core
Core (IFR) (IER) (INTM)
Interrupt “Latch” “Switch” “Global Switch”

INT1 1

INT2 0 C28x
Core

INT14 1

 A valid signal on a specific interrupt line causes the latch
to display a “1” in the appropriate bit

 If the individual and global switches are turned “on” the
interrupt reaches the core

Interrupt Flag Register (IFR)
15 14 13 12 11 10 9 8
RTOSINT DLOGINT INT14 INT13 INT12 INT11 INT10 INT9

7 6 5 4 3 2 1 0
INT8 INT7 INT6 INT5 INT4 INT3 INT2 INT1

Pending : IFR Bit = 1
Absent : IFR Bit = 0

/*** Manual setting/clearing IFR ***/
extern cregister volatile unsigned int IFR;
IFR |= 0x0008; //set INT4 in IFR
IFR &= 0xFFF7; //clear INT4 in IFR
Compiler generates atomic instructions (non-interruptible) for setting/clearing IFR
 If interrupt occurs when writing IFR, interrupt has priority
 IFR(bit) cleared when interrupt is acknowledged by CPU
 Register cleared on reset

15
Interrupt Enable Register (IER)
14 13 12 11 10 9 8
RTOSINT DLOGINT INT14 INT13 INT12 INT11 INT10 INT9

7 6 5 4 3 2 1 0
INT8 INT7 INT6 INT5 INT4 INT3 INT2 INT1

Enable: Set IER Bit = 1
Disable: Clear IER Bit = 0

/*** Interrupt Enable Register ***/
extern cregister volatile unsigned int IER;
IER |= 0x0008; //enable INT4 in IER
IER &= 0xFFF7; //disable INT4 in IER

 Compiler generates atomic instructions (non-interruptible)
for setting/clearing IER
 Register cleared on reset

Interrupt Global Mask Bit
Bit 0
ST1 INTM

• INTM used to globally enable/disable interrupts:
– Enable: INTM = 0
– Disable: INTM = 1 (reset value)
• INTM modified from assembly code only:

/*** Global Interrupts ***/
asm(“ CLRC INTM”); //enable global interrupts
asm(“ SETC INTM”); //disable global interrupts


Peripheral Interrupt Expansion - PIE Interrupt Group 1
PIE module for 96 Interrupts
PIEIFR1 PIEIER1
INT1.x interrupt group INT1.1 1
INT2.x interrupt group
INT1.2 0
INT3.x interrupt group INT1
• •
INT4.x interrupt group • •
• •
INT1.8 1
96
28x Core Interrupt logic
INT9.x interrupt group INT1 – INT 12

28x

INTM

IER
IFR
12 Interrupts
INT11.x interrupt group Core
r e n l ar e hp r e P

i

INT13 (TINT1 / XINT13)
INT14 (TINT2)
NMI
t I


PIE Registers
PIEIFRx register (x = 1 to 12)
15 - 8 7 6 5 4 3 2 1 0
reserved INTx.8 INTx.7 INTx.6 INTx.5 INTx.4 INTx.3 INTx.2 INTx.1

PIEIERx register (x = 1 to 12)
15 - 8 7 6 5 4 3 2 1 0
reserved INTx.8 INTx.7 INTx.6 INTx.5 INTx.4 INTx.3 INTx.2 INTx.1

PIE Interrupt Acknowledge Register (PIEACK)
15 - 12 11 10 9 8 7 6 5 4 3 2 1 0
reserved PIEACKx

PIECTRL register 15 - 1 0
PIEVECT ENPIE

#include “DSP28_Device.h”
PieCtrlRegs.PIEIFR1.bit.INTx4 = 1; //manually set IFR for XINT1 in PIE group 1
PieCtrlRegs.PIEIER3.bit.INTx5 = 1; //enable CAPINT1 in PIE group 3
PieCtrlRegs.PIEACK.all = 0x0004; //acknowledge the PIE group 3
Technology beyond the Dreams™ = 1; //enable the PIE Copyright © 2006 Pantech Solutions Pvt
PieCtrlRegs.PIECTRL.bit.ENPIE

Default Interrupt Vector Table at Reset
Prio Vector Offset
1 Reset 00 Default Vector Table
5 Int 1 02 Remapped when
6 Int 2 04 ENPIE = 1
7 Int 3 06 Memory
8 Int 4 08 0
9 Int 5 0A
10 Int 6 0C
11
Int 7 0E
12
13 Int 8 10
0x00 0D00
14 Int 9 12
Int 10 PIE Vectors
15 14
256 W
16 Int 11 16
17 Int 12 18
18 Int 13 1A
19 Int 14 1C 0x3F FFC0
BROM Vectors
DlogInt 1E 64 W
4 RtosInt 20 0x3F FFFF
2 EmuInt 22
3 NMI 24
PIE vector generated by config Tool
- Illegal 26
Used to initialize PIE vectors
- User 1-12 28-3E

PIE Vector Mapping (ENPIE
Vector name PIE vector address PIE vector Description
t used 0x00 0D00 Reset Vector Never Fetched Here

= 1)
INT1 0x00 0D02 INT1 re-mapped below
…… …… …… re-mapped below
INT12 0x00 0D18 INT12 re-mapped below
INT13 0x00 0D1A XINT1 Interrupt Vector
INT14 0x00 0D1C Timer2 – RTOS Vector
Datalog 0x00 0D1D Data logging vector
…… …… ……
USER11 0x00 0D3E User defined TRAP
INT1.1 0x00 0D40 PIEINT1.1 interrupt vector
…… …… ……
INT1.8 0x00 0D4E PIEINT1.8 interrupt vector
…… …… ……
INT12.1 0x00 0DF0 PIEINT12.1 interrupt vector
…… …… ……
INT12.8 0x00 0DFE PIEINT12.8 interrupt vector
 PIE vector space - 0x00 0D00 – 256 Word memory in Data space

 RESET and INT1-INT12 vector locations are Re-mapped

Technology beyond are remapped to 0x00 0D00 in Data space © 2006 Pantech Solutions Pvt
 CPU vectors
the Dreams™ Copyright

INT1
F2812/10 PIE Interrupt
INTx.8

WAKEINT
INTx.7

TINT0
INTx.6

ADCINT
INTx.5

XINT2
INTx.4

XINT1
INTx.3 INTx.2

PDPINTB
INTx.1

PDPINTA

INT2 Assignment Table
T1OFINT T1UFINT T1CINT T1PINT CMP3INT CMP2INT CMP1INT

INT3 CAPINT3 CAPINT2 CAPINT1 T2OFINT T2UFINT T2CINT T2PINT

INT4 T3OFINT T3UFINT T3CINT T3PINT CMP6INT CMP5INT CMP4INT

INT5 CAPINT6 CAPINT5 CAPINT4 T4OFINT T4UFINT T4CINT T4PINT

INT6 MXINT MRINT SPITXINTA SPIRXINTA

INT7

INT8

INT9 ECAN1INT ECAN0INT SCITXINTB SCIRXINTB SCITXINTA SCIRXINTA

INT10

INT11

INT12


_int00 >

F FFCO> = Boot-ROM Code
F FFCO> = Boot-ROM Code
F 7FF6 > = LB _c_int00
F 7FF6 > = LB _c_int00

hip ROM memory)
hip ROM memory)
int00 >
Device Vector Mapping - Summary RESET

MPNMC = 1 (external memory XINTF)
MPNMC = 1 (external memory XINTF)
User Code Start < _c_int00>
Reset Vector <0x3F FFCO> = _c_int00
Reset Vector <0x3F FFCO> = _c_int00
_c_int00:
. . .
CALL main()
Initialization ( )
{
EALLOW
main() Load PIE Vectors PIE Vector Table
{ initialization(); Enable the PIEIER
256 Word RAM
. . . Enable PIECTRL
Enable Core IER 0x00 0D00 – 0DFF
}
Enable INTM
EDIS
}


Interrupt Response - Hardware Sequence
CPU Action Description
Registers → stack 14 Register words auto saved
0 → IFR (bit) Clear corresponding IFR bit
0 → IER (bit) Clear corresponding IER bit
1 → INTM/DBGM Disable global ints/debug events
Vector → PC Loads PC with int vector address
Clear other status bits Clear LOOP, EALLOW, IDLESTAT

Note: some actions occur simultaneously, none are interruptible
T ST0
AH AL
PH PL
AR1 AR0
DP ST1
DBSTAT IER
PC(msw) PC(lsw)

Latency
ext.
interrupt
occurs
Interrupt Latency
Internal
interrupt
occurs
Assumes ISR in
internal RAM
here here

cycles
2 4 3 3 1 3
Recognition Get vector ISR
Sync ext. PF1/PF2/D1 Save D2/R1/R2 of instruction
signal delay (3) and (3 reg. of ISR return ISR executed on
SP alignment pairs instruction address instruction
(ext. interrupt (1) saved) next cycle
(3 reg. pairs
only) saved)

Above is for PIE enabled or disabled

 Minimum latency (to when real work occurs in the ISR):
 Internal interrupts: 14 cycles
 External interrupts: 16 cycles
 Maximum latency: Depends on wait states, ready, INTM, etc.

C28x CPU Timers
RESET

Timer Reload

16 - Bit divide down 32 - Bit period
TDDRH:TDDR PRDH:PRD

SYSCLKOUT
16 - Bit prescaler 32 - Bit counter
PSCH:PSC TIMH:TIM
TCR.4

BORROW

INT


C28x Timer Interrupt System
PIE unit
TINT0
INT1.7 interrupt
28x Core Interrupt logic
INT1

TINT1 / XINT13 INT13 28x

INTM
IER
IFR
Core
INT14
TINT2


C28x Timer Registers
Address Register Name
0x0000 0C00 TIMER0TIM Timer 0, Counter Register Low
0x0000 0C01 TIMER0TIMH Timer 0, Counter Register High
0x0000 0C02 TIMER0PRD Timer 0, Period Register Low
0x0000 0C03 TIMER0PRDH Timer 0, Period Register High
0x0000 0C04 TIMER0TCR Timer 0, Control Register
0x0000 0C06 TIMER0TPR Timer 0, Prescaler Register
0x0000 0C07 TIMER0TPRH Timer 0, Prescaler Register High
0x0000 0C08 TIMER1TIM Timer 1, Counter Register Low
0x0000 0C09 TIMER1TIMH Timer 1, Counter Register High
0x0000 0C0A TIMER1PRD Timer 1, Period Register Low
0x0000 0C0B TIMER1PRDH Timer 1, Period Register High
0x0000 0C0C TIMER1TCR Timer 1, Control Register
0x0000 0C0D TIMER1TPR Timer 1, Prescaler Register
0x0000 0C0F TIMER1TPRH Timer 1, Prescaler Register High

0x0000 0C10 to 0C17 Timer 2 Registers ; same layout as above


C28x Timer Control Registers
TIMERxTCR Emulator Interaction
Timer Interrupt Flag Timer Interrupt Enable 1x = run free
Write 1 clear bit Write 1 to enable INT

15 14 13 12 11 10 9 8
TIF TIE reserved reserved FREE SOFT reserved reserved

7 6 5 4 3 2 1 0
reserved reserved TRB TSS reserved reserved reserved reserved

Timer Reload Bit Timer Stop Status
1 = reload 0 = start / 1 = stop


Interrupt system f28x

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