Configure Laser-PWM to D6

[botboe]

I'd like to use pin D6 for my laser-pwm-signal because I don't need a mosfet-controlled power-source as the laser has its own driverboard. I modified the ramps-section of cpu_maps.h correspondingly:

  // Define spindle output pins.
  #define SPINDLE_PWM_DDR   DDRH
  #define SPINDLE_PWM_PORT  PORTH
  #define SPINDLE_PWM_BIT   3 // MEGA2560 Digital Pin 6

Unfortunately I don't get any pwm-output - no matter if in lasermode or not. Did I make anything wrong?

[walterwissmann]

Hi `Mad-Onion,

have you set the right OCR_register to PWM_BIT 3? It must be T4A

regards Walter: `

[botboe]

Hi Walter,

that might be the little detail I forgot about. I haven't configured PWM-timers by registers for years :-D I will have a look at it later and give you feedback.

Best regards Tobias

[walterwissmann]

Thx :)

[botboe]

This is my current configuration, but instead of using PWM the output jumps between 0 and 5 volts - no linear change.

  // Advanced Configuration Below You should not need to touch these variables
  // Set Timer up to use TIMER4B which is attached to Digital Pin 8 - Ramps 1.4 12v output with heat sink
  #define SPINDLE_PWM_MAX_VALUE     1024.0 // Translates to about 1.9 kHz PWM frequency at 1/8 prescaler
  #ifndef SPINDLE_PWM_MIN_VALUE
  #define SPINDLE_PWM_MIN_VALUE   1   // Must be greater than zero.
  #endif
  #define SPINDLE_PWM_OFF_VALUE     0
  #define SPINDLE_PWM_RANGE         (SPINDLE_PWM_MAX_VALUE-SPINDLE_PWM_MIN_VALUE)

  //Control Digital Pin 6 which is Servo 2 signal pin on Ramps 1.4 board
  #define SPINDLE_TCCRA_REGISTER    TCCR4A
  #define SPINDLE_TCCRB_REGISTER    TCCR4B
  #define SPINDLE_OCR_REGISTER      OCR4A
  #define SPINDLE_COMB_BIT          COM4A1

  // 1/8 Prescaler, 16-bit Fast PWM mode
  #define SPINDLE_TCCRA_INIT_MASK ((1<<WGM40) | (1<<WGM41))
  #define SPINDLE_TCCRB_INIT_MASK ((1<<WGM42) | (1<<WGM43) | (1<<CS41))
  #define SPINDLE_OCRA_REGISTER   OCR4A // 16-bit Fast PWM mode requires top reset value stored here.
  #define SPINDLE_OCRA_TOP_VALUE  0x0400 // PWM counter reset value. Should be the same as PWM_MAX_VALUE in hex.

  // Define spindle output pins.
  #define SPINDLE_PWM_DDR   DDRH
  #define SPINDLE_PWM_PORT  PORTH
  #define SPINDLE_PWM_BIT   3     // MEGA2560 Digital Pin 6

[walterwissmann]

Hmm, my code on PIN D8 with PH5 and T4C:

// Advanced Configuration Below You should not need to touch these variables // Set Timer up to use TIMER4C which is attached to Digital Pin 8

define SPINDLE_PWM_MAX_VALUE 1024.0 // Translates to about 1.9 kHz PWM frequency at 1/8 prescaler

ifndef SPINDLE_PWM_MIN_VALUE

#define SPINDLE_PWM_MIN_VALUE   1   // Must be greater than zero.

endif

define SPINDLE_PWM_OFF_VALUE 0

define SPINDLE_PWM_RANGE (SPINDLE_PWM_MAX_VALUE-SPINDLE_PWM_MIN_VALUE)

define SPINDLE_TCCRA_REGISTER TCCR4A

define SPINDLE_TCCRB_REGISTER TCCR4B

define SPINDLE_OCR_REGISTER OCR4C

define SPINDLE_COMB_BIT COM4C1

// 1/8 Prescaler, 16-bit Fast PWM mode

define SPINDLE_TCCRA_INIT_MASK ((1<<WGM40) | (1<<WGM41))

define SPINDLE_TCCRB_INIT_MASK ((1<<WGM42) | (1<<WGM43) | (1<<CS41))

define SPINDLE_OCRA_REGISTER OCR4A // 16-bit Fast PWM mode requires top reset value stored here.

define SPINDLE_OCRA_TOP_VALUE 0x0400 // PWM counter reset value. Should be the same as PWM_MAX_VALUE in hex.

// Define spindle output pins.

define SPINDLE_PWM_DDR DDRH

define SPINDLE_PWM_PORT PORTH

define SPINDLE_PWM_BIT 5 // MEGA2560 Digital Pin 8

workes great... How have you measure the output voltage? Could it be, in lasermode is the PWM-output a On/Off-Switch?

BR Walter

[walterwissmann]

Update: Lasermode On($32=1): no PWM Spindel Enable: high with M3 Spindel Dir: high with M4 M5 both low

Lasermode off ($32=0): PWM Spindel Enable: high with M3 Spindel Dir: high with M4 M5 both low, PWM=0

BR Walter

[botboe]

Sorry for my late response, problem was already solved here. You have to watch out as it is a 8bit-timer instead of 10bit as the D8-pin.