ARM Learning Notes---Interrupts

Interrupt priority from high to low

51 single-chip microcomputer: INT0 (P3.2), TIMER0, INT1 (P3.3), TIMER1, serial port interrupt (P3.0, P3.1)

52 single chip microcomputer:TIMER2

External interrupt falling edge trigger

Internal timer: TMOD register (M1M0)

M1 M0 method

0 0 0 13 bits

0 1 1 16 bits

1 0 2 8 auto

1 1 3 Two 8-bit

Serial port {RI->while(RI!)

TI->while(TI!)}

When an interrupt occurs while executing an instruction, execute this instruction first and then handle the interrupt.

The way the microcontroller exchanges information with the outside world: polling, interrupt, DMA

2451 53 interrupt sources

Program initial address: 0x30000000

Interrupt vector address: 0x00000000

Interrupt Mode:

IRQ: Normal trigger interrupt mode

FIQ: Fast interrupt mode (used in emergency situations, high priority)

register:

SRCPND1 first identification register, 32 bits, corresponding to the interrupt request, this position is 1, the default value is 0

INTMSK mask register, 32 bits, the corresponding interrupt is masked and this position is 1, the default is 1

INTPND tail mark register, 32 bits, same as the first mark register

SUBSRCPND sub-identification register, 32 bits,

INTSUBMSK Sub-mask register, 32 bits,

PRIORITY priority register, 28 bits,

INTMOD mode register, 32 bits, all set to 0 by default, 0 represents IRQ mode, 1 represents FIQ

(Not blocked)->INTMODE (IRQ)->PRIORITY (10, 12, 28)->INTPND (10 position 1)->INTOFFSET (set to 10)->TIMR0 interrupt service function (ISR)->INTPND, SRCPND, SUBSRCPN

Clear the 10th interrupt flag

1. Default priority order

2. No blocking

3.IRQ Mode

Timer interrupt:

51 single chip microcomputer:

Clock cycle: 1/110592M = 1.09us, 1/12M

Mechanical cycle: 12*1.09us,

2 mechanical cycles = 1 beat

Instruction cycle = several mechanical cycles (>=1)

T0, 1, 16-bit TH0 (high 8 bits); add count->65535 overflow

2^16 - 1 = 65535

12M Mechanical cycle 1us

65.535ms

Timing 50ms

TH0 = (65535-50000)/256; //high 8 bits

TL0 = (65535-50000)%256; //low 8 bits

2451:

PWM: Duty cycle High level time

register:

TCFG: Prescaler register, 32 bits

TCON: Timer control register, 22 bits

TCNTB: Count Register

TCMPB: Compare Register

TCNTO: Observing TCNTB

Simple timer initialization steps:

1. Configure the pre-scaling factor (199)

2. Configure the frequency division coefficient (8)

3. Configure the initial value of the count (41250)

4. Configure as automatic reload function (TCON)

5. Update initial value (TCON)

6. Start the timer (TCON)

7. Clear bit (Update initial value control bit) (TCON)