main.c

8位定时器H1(PWM 输出)

/*******************************************************************************

	NEC Electronics     78K0S/KB1+

********************************************************************************
	78K0S/KB1+	Sample program
********************************************************************************
	8-bit timer H1 (PWM output)
********************************************************************************
<<History>>
	2007.7.--	Release
********************************************************************************

<<Overview>>

This sample program presents an example of using the PWM output function of 8-
bit timer H1.  The LED1 brightness is controlled through the PWM output duty 
by connecting the timer output (TOH1 pin) of 8-bit timer H1 to LED1.  The duty 
is changed at a cycle of 500 ms by using timer H1 interrupts and LED2 output 
is reversed simultaneously.


  <Principal setting contents>

  - Stop the watchdog timer operation
  - Set the low-voltage detection voltage (VLVI) to 4.3 V +-0.2 V
  - Generate an internal reset signal (low-voltage detector) when VDD < VLVI after VDD >= VLVI
  - Set the CPU clock to 8 MHz
  - Set the clock supplied to the peripheral hardware to 8 MHz


  <8-bit timer H1 settings>
  - Set to the PWM mode
  - Enable timer output of the TOH1 pin
  - Count clock = fxp/2^6 (125 kHz)
  - Timer cycle = 2 ms (8[us/clk] x 250[count] = 2[ms])


  <PWM output duty and LEDs>
   
  - LED2 output is reversed simultaneously with the duty that is changed every 500 ms in the following order.
    +-----------------+-----------------------------+
    | PWM output duty | 10% | 30% | 50% | 70% | 90% | (Hereafter, repeated from 10%)
    +-----------------+-----------------------------+
    | LED1 brightness | 90% | 70% | 50% | 30% | 10% |
    +-----------------+-----------------------------+
    # PWM output is high active and LED1 is low active; therefore, the LED 
      brightness = 100 - duty factor.


<<I/O port settings>>

  Input: -
  Output: P00-P03, P20-P23, P30-P33, P40-P47, P120-P123, P130
  # All unused ports are set as the output mode.

*******************************************************************************/


/*==============================================================================

	Preprocessing directive (#pragma)

==============================================================================*/
#pragma	SFR				/* SFR names can be described at the C source level */
#pragma	EI				/* EI instructions can be described at the C source level */
#pragma	NOP				/* NOP instructions can be described at the C source level */
#pragma interrupt INTTMH1 fn_inttmH1	/* Interrupt function declaration:INTTMH1 */

/*==============================================================================

	Define the global variables

==============================================================================*/
sreg unsigned char ucTMH1cnt = 250;	/* 8-bit variable for counting the number of INTTMH1 interrupts */

/*******************************************************************************

	Initialization after RESET

*******************************************************************************/
void hdwinit(void){
	unsigned char ucCnt200us;	/* 8-bit variable for 200 us wait */

/*------------------------------------------------------------------------------
	Initialize the watchdog timer + detect low-voltage + set the clock
------------------------------------------------------------------------------*/
	/* Initialize the watchdog timer */
	WDTM  = 0b01110111;		/* Stop the watchdog timer operation */
	
	/* Set the clock <1> */
	PCC   = 0b00000000;		/* The clock supplied to the CPU (fcpu) = fxp (= fx/4 = 2 MHz) */
	LSRCM = 0b00000001;		/* Stop the oscillation of the low-speed internal oscillator */
	
	/* Check the reset source */
	if (!(RESF & 0b00000001)){	/* Omit subsequent LVI-related processing during LVI reset */
		
		/* Set low-voltage detection */
		LVIS  = 0b00000000;	/* Set the low-voltage detection level (VLVI) to 4.3 V +-0.2 V */
		LVION = 1;		/* Enable the low-voltage detector operation */
		
		for (ucCnt200us = 0; ucCnt200us < 9; ucCnt200us++){	/* Wait of about 200 us */
			NOP();
		}
		
		while (LVIF){		/* Wait for VDD >= VLVI */
			NOP();
		}
		
		LVIMD = 1;		/* Set so that an internal reset signal is generated when VDD < VLVI */
	}
	
	/* Set the clock <2> */
	PPCC  = 0b00000000;		/* The clock supplied to the peripheral hardware (fxp) = fx (= 8 MHz)
					   -> The clock supplied to the CPU (fcpu) = fxp = 8 MHz */

/*------------------------------------------------------------------------------
	Initialize the port 0
------------------------------------------------------------------------------*/
	P0    = 0b00000000;		/* Set output latches of P00-P03 as low */
	PM0   = 0b11110000;		/* Set P00-P03 as output mode */

/*------------------------------------------------------------------------------
	Initialize the port 2
------------------------------------------------------------------------------*/
	P2    = 0b00000000;		/* Set output latches of P20-P23 as low (P21: turn on LED2) */
	PM2   = 0b11110000;		/* Set P20-P23 as output mode */

/*------------------------------------------------------------------------------
	Initialize the port 3
------------------------------------------------------------------------------*/
	P3    = 0b00000000;		/* Set output latches of P30-P33 as low */
	PM3   = 0b11110000;		/* Set P30-P33 as output mode */

/*------------------------------------------------------------------------------
	Initialize the port 4
------------------------------------------------------------------------------*/
	P4    = 0b00000000;		/* Set output latches of P40-P47 as low (P42: turn on LED1) */
	PM4   = 0b00000000;		/* Set P40-P47 as output mode */

/*------------------------------------------------------------------------------
	Initialize the port 12
------------------------------------------------------------------------------*/
	P12   = 0b00000000;		/* Set output latches of P120-P123 as low */
	PM12  = 0b11110000;		/* Set P120-P123 as output mode */

/*------------------------------------------------------------------------------
	Initialize the port 13
------------------------------------------------------------------------------*/
	P13   = 0b00000001;		/* Set output latch of P130 as high */

/*------------------------------------------------------------------------------
	Set 8-bit timer H1
------------------------------------------------------------------------------*/
	TMHMD1 = 0b00111001;		/* Count clock = fxp/2^6 = 125 kHz, PWM mode, enable TOH1 output */
	CMP01 = 250-1;			/* Initialize CMP01 (cycle: 2 ms) */
	CMP11 = 25-1;			/* Initialize CMP11 (duty: 10%) */
	TMHE1 = 1;			/* Start the timer operation */

/*------------------------------------------------------------------------------
	Set the interrupt
------------------------------------------------------------------------------*/
	IF0   = 0x00;		/* Clear invalid interrupt requests in advance */
	TMMKH1 = 0;			/* Unmask INTTMH1 interrupts */

	return;
}

/*******************************************************************************

	Main loop

*******************************************************************************/
void main(void){
	
	EI();				/* Enable vector interrupt */
	
	while (1){
		NOP();
		NOP();
	}
}

/*******************************************************************************

	Interrupt INTTMH1

*******************************************************************************/
__interrupt void fn_inttmH1(){
	
	if (--ucTMH1cnt == 0){	/* Processing when the number of INTTMH1 interrupts is 250 */
		
		ucTMH1cnt = 250;	/* Initialize the number of interrupts */
		P2 ^= 0b00000010;	/* Reverse LED2 */
		
		if (CMP11 >= 225-1){	/* Processing when the duty is at least 90% */
			CMP11 = 25-1;	/* Initialize the duty to 10% */
		}
		else {
			CMP11 += 50;	/* Increase the duty by 20% */
		}
	}
	
	return;
}