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@c-toyama(riki toy)

A-Axisを制御したい！Arduino Mega2560 + CNC シールド v3.0 の覚書

Last updated at Posted at 2023-03-13

初めに

Arduino UnoとCNCシールドで4軸を動かしたく調べてた備忘録
⇒結局はMega2560とCNCシールドに補助シールドを起こすことで対応

使用したもの

ライブラリは下記を使用
https://github.com/mlambm/grbl

ライブラリの問題点

上記ライブラリで4軸目のA軸も無事に動いたが A軸用のリミットスイッチがない

確認した内容

A軸用のリミットスイッチを設けるためソースを見ていくと digitalWrite や analogWrite でなく ポートを直接いじっている模様
太刀打ちできんのでChatGPTに聞くも毎回珍回答ばかりで調べた結果が次の通り

ATmega328pのピン番号 ポート番号 Arduino Unoのピン番号 CNCシールド v3.0のピン名 備考
1 PC6(RESET/PCINT14)
2 PD0(PCINT16) D0 RXのため使用しない
3 PD1(PCINT17) D1 TXのため使用しない
4 PD2(PCINT18) D2 X-STEP
5 PD3(PCINT19) D3 Y-STEP
6 PD4(PCINT20) D4 Z-STEP
7 VCC 電源電圧
8 GND グランド
9 PB6(XTAL1/PCINT6) クリスタル1
10 PB7(XTAL2/PCINT7) クリスタル2
11 PD5(PCINT21) D5 X-DIR
12 PD6(PCINT22) D6 Y-DIR
13 PD7(PCINT23) D7 Z-DIR
14 PB0(PCINT0) D8 EN ドライバーの有効・無効
15 PB1(PCINT1) D9 X-EndStop Limit X-Axis
16 PB2(PCINT2) D10 Y-EndStop Limit Y-Axis
17 PB3(PCINT3) D11 Z-EndStop Limit Z-Axis
18 PB4(PCINT4) D12 SpinEnable(A.STP)
19 PB5(PCINT5) D13 SpinDir(A.DIR)
20 AVCC
21 AREF
22 AGND
23 PC0(PCINT8) D14 / A0 ABORT
24 PC1(PCINT9) D15 / A1 HOLD
25 PC2(PCINT10) D16 / A2 RESUME
26 PC3(PCINT11) D17 / A3 Coolant
27 PC4(PCINT12) D18 / A4 for I2C(SDA)?
28 PC5(PCINT13) D19 / A5 for I2C(SCL)?
CNCシールドのピン 説明
Step[XYZ] [XYZ]軸の回転方向
Probe ワークピースの位置を確認するためのセンサー
Spindle 主軸（カッター）の回転を制御するためのピン
Coolant 冷却液を制御するためのピン

schematic
pcb-font
pcb-rear
Arduino Uno
Unoの回路図

Coolant が使えるのかな
⇒使えないわけではない様だが外部割込みは一つのポートで完結しないとプログラムが大変らしい

結論その1

結論Unoだとピンが足りない！

Mega2560 に鞍替え

では沢山ポートがある Mega2560 でならので何とかなるだろう！と鞍替え
...リミットスイッチがPin Change Interrupt register に属してないといけないから自分の知識では結構難しかった💦

megaAVR® データシート

これの 13. 外部割り込み に詳細が書かれている
PCIE0, PCIE1, PCIE2は54頁

Pin Change Interrupt Enable # PIN Pin Change Enable Mask #
PCIE0 PCINT0～PCINT7 PCMSK0
PCIE1 PCINT8～PCINT15 PCMSK1
PCIE2 PCINT16～PCINT23 PCMSK2

なるほど
ATmega2560 には Pin Change Interrupt Register は3つあるが PCMSK1 は Mega2560 では使用できない事が判明

ということで次の様になった

CNCシールドのものを直接使用するのは断念しサブシールドを作成して対応

Mega2560 ポート 役割 備考
D22 PA0 X-step
D24 PA2 Y-step
D26 PA4 Z-step
D28 PA6 A-step
D31 PC6 X-dir
D33 PC4 Y-dir
D35 PC2 Z-dir
D37 PC0 A-dir
A8 PK0 X-limit PCMSK2 PCINT16
A9 PK1 Y-limit PCMSK2 PCINT17
A10 PK2 Z-limit PCMSK2 PCINT18
A11 PK3 A-limit PCMSK2 PCINT19
D50 PB3 Reset PCMSK0 PCINT3
D51 PB2 Feed Hold PCMSK0 PCINT2
D52 PB1 Sycle State PCMSK0 PCINT1
D53 PB0 Safty Door PCMSK0 PCINT0

いじったのは次のファイル

config.h
#define CPU_MAP_ATMEGA2560

#define HOMING_CYCLE_2 ((1<<A_AXIS))
limits.c, report.c
N_AXIS3 -> N_AXIS4
settings.c
// Returns limit pin mask according to Grbl internal axis indexing.
uint8_t get_limit_pin_mask(uint8_t axis_idx)
{
  if ( axis_idx == X_AXIS ) { return((1<<X_LIMIT_BIT)); }
  if ( axis_idx == Y_AXIS ) { return((1<<Y_LIMIT_BIT)); }
  if ( axis_idx == Z_AXIS ) { return((1<<Z_LIMIT_BIT)); }
  return((1<<A_LIMIT_BIT));
}
stepper.c
  #if defCPU_MAP_ATMEGA328P
    uint8_t step_bits[2];  // Stores out_bits output to complete the step pulse delay
  #else
    uint8_t step_bits;  // Stores out_bits output to complete the step pulse delay
  #endif

---

ISR(TIMER1_COMPA_vect)
{        
// SPINDLE_ENABLE_PORT ^= 1<<SPINDLE_ENABLE_BIT; // Debug: Used to time ISR
  if (busy) { return; } // The busy-flag is used to avoid reentering this interrupt
  
#ifdef CPU_MAP_ATMEGA328P
  // Set the direction pins a couple of nanoseconds before we step the steppers
  DIRECTION_PORT0 = (DIRECTION_PORT0 & ~DIRECTION_MASK0) | (st.dir_outbits & DIRECTION_MASK0);

  // Then pulse the stepping pins
  #ifdef STEP_PULSE_DELAY
    st.step_bits[0] = (STEP_PORT0 & ~STEP_MASK0) | (st.step_outbits & STEP_MASK0); // Store out_bits to prevent overwriting.
  #else  // Normal operation
    STEP_PORT0 = (STEP_PORT0 & ~STEP_MASK0) | st.step_outbits & STEP_MASK0;
  #endif  

  // Set the direction pins a couple of nanoseconds before we step the steppers
  DIRECTION_PORT1 = (DIRECTION_PORT1 & ~DIRECTION_MASK1) | ((st.dir_outbits<<4) & DIRECTION_MASK1);

  // Then pulse the stepping pins
  #ifdef STEP_PULSE_DELAY
    st.step_bits[1] = (STEP_PORT1 & ~STEP_MASK1) | ((st.step_outbits<<4) & STEP_MASK1); // Store out_bits to prevent overwriting.
  #else  // Normal operation
    STEP_PORT1 = (STEP_PORT1 & ~STEP_MASK1) | (st.step_outbits<<4) & STEP_MASK1;
  #endif
#else
  // Set the direction pins a couple of nanoseconds before we step the steppers
  DIRECTION_PORT = (DIRECTION_PORT & ~DIRECTION_MASK) | (st.dir_outbits & DIRECTION_MASK);

  // Then pulse the stepping pins
  #ifdef STEP_PULSE_DELAY
    st.step_bits = (STEP_PORT & ~STEP_MASK) | st.step_outbits; // Store out_bits to prevent overwriting.
  #else  // Normal operation
    STEP_PORT = (STEP_PORT & ~STEP_MASK) | st.step_outbits;
  #endif  
#endif

---

ISR(TIMER0_OVF_vect)
{
  // Reset stepping pins (leave the direction pins)
#ifdef CPU_MAP_ATMEGA328P
  STEP_PORT0 = (STEP_PORT0 & ~STEP_MASK0) | (step_port_invert_mask & STEP_MASK0); 
  STEP_PORT1 = (STEP_PORT1 & ~STEP_MASK1) | (step_port_invert_mask & STEP_MASK1); 
#else
  STEP_PORT = (STEP_PORT & ~STEP_MASK) | (step_port_invert_mask & STEP_MASK); 
#endif
  TCCR0B = 0; // Disable Timer0 to prevent re-entering this interrupt when it's not needed. 
}
#ifdef STEP_PULSE_DELAY
  // This interrupt is used only when STEP_PULSE_DELAY is enabled. Here, the step pulse is
  // initiated after the STEP_PULSE_DELAY time period has elapsed. The ISR TIMER2_OVF interrupt
  // will then trigger after the appropriate settings.pulse_microseconds, as in normal operation.
  // The new timing between direction, step pulse, and step complete events are setup in the
  // st_wake_up() routine.
  ISR(TIMER0_COMPA_vect) 
  { 
#ifdef CPU_MAP_ATMEGA328P
    STEP_PORT0 = st.step_bits[0]; // Begin step pulse.
    STEP_PORT1 = st.step_bits[1]; // Begin step pulse.
#else
    STEP_PORT = st.step_bits; // Begin step pulse.
#endif
  }
#endif

---

// Initialize and start the stepper motor subsystem
void stepper_init()
{
  // Configure step and direction interface pins
#ifdef CPU_MAP_ATMEGA328P
  STEP_DDR0 |= STEP_MASK0;
  STEP_DDR1 |= STEP_MASK1;
  STEPPERS_DISABLE_DDR |= 1<<STEPPERS_DISABLE_BIT;
  DIRECTION_DDR0 |= DIRECTION_MASK0;
  DIRECTION_DDR1 |= DIRECTION_MASK1;
#else
  STEP_DDR |= STEP_MASK;
  STEPPERS_DISABLE_DDR |= 1<<STEPPERS_DISABLE_BIT;
  DIRECTION_DDR |= DIRECTION_MASK;
#endif
cpu_map/cpu_map_atmega2560.h
#define X_STEP_BIT    0 // MEGA2560 Digital Pin 22
#define Y_STEP_BIT    2 // MEGA2560 Digital Pin 24
#define Z_STEP_BIT    4 // MEGA2560 Digital Pin 26
#define A_STEP_BIT    6 // MEGA2560 Digital Pin 28
#define STEP_MASK ((1<<X_STEP_BIT)|(1<<Y_STEP_BIT)|(1<<Z_STEP_BIT)|(1<<A_STEP_BIT)) // All step bits

// Define step direction output pins. NOTE: All direction pins must be on the same port.
#define DIRECTION_DDR     DDRC
#define DIRECTION_PORT    PORTC
#define DIRECTION_PIN     PINC
#define X_DIRECTION_BIT   6 // MEGA2560 Digital Pin 31
#define Y_DIRECTION_BIT   4 // MEGA2560 Digital Pin 33
#define Z_DIRECTION_BIT   2 // MEGA2560 Digital Pin 35
#define A_DIRECTION_BIT   0 // MEGA2560 Digital Pin 37
#define DIRECTION_MASK ((1<<X_DIRECTION_BIT)|(1<<Y_DIRECTION_BIT)|(1<<Z_DIRECTION_BIT)|(1<<A_DIRECTION_BIT)) // All direction bits

// Define stepper driver enable/disable output pin.
#define STEPPERS_DISABLE_DDR   DDRH
#define STEPPERS_DISABLE_PORT  PORTH
#define STEPPERS_DISABLE_BIT   5 // MEGA2560 Digital Pin 8
#define STEPPERS_DISABLE_MASK (1<<STEPPERS_DISABLE_BIT)

// Define homing/hard limit switch input pins and limit interrupt vectors. 
// NOTE: All limit bit pins must be on the same port
#define LIMIT_DDR       DDRK
#define LIMIT_PORT      PORTK
#define LIMIT_PIN       PINK
#define X_LIMIT_BIT     0 // MEGA2560 Analog Pin A8
#define Y_LIMIT_BIT     1 // MEGA2560 Analog Pin A9
#define Z_LIMIT_BIT     2 // MEGA2560 Analog Pin A10
#define A_LIMIT_BIT     3 // MEGA2560 Analog Pin A11
#define LIMIT_INT       PCIE2  // Pin change interrupt enable pin
#define LIMIT_INT_vect  PCINT2_vect
#define LIMIT_PCMSK     PCMSK2 // Pin change interrupt register
#define LIMIT_MASK ((1<<X_LIMIT_BIT)|(1<<Y_LIMIT_BIT)|(1<<Z_LIMIT_BIT)|(1<<A_LIMIT_BIT)) // All limit bits

// Define spindle enable and spindle direction output pins.
#define SPINDLE_ENABLE_DDR      DDRB
#define SPINDLE_ENABLE_PORT     PORTB
#define SPINDLE_ENABLE_BIT      6 // MEGA2560 Digital Pin 12
#define SPINDLE_DIRECTION_DDR   DDRB
#define SPINDLE_DIRECTION_PORT  PORTB
#define SPINDLE_DIRECTION_BIT   7 // MEGA2560 Digital Pin 13

// Define flood and mist coolant enable output pins.
// NOTE: Uno analog pins 4 and 5 are reserved for an i2c interface, and may be installed at
// a later date if flash and memory space allows.
// #define COOLANT_FLOOD_DDR     DDRH
// #define COOLANT_FLOOD_PORT    PORTH
// #define COOLANT_FLOOD_BIT     5 // MEGA2560 Digital Pin 8
#ifdef ENABLE_M7 // Mist coolant disabled by default. See config.h to enable/disable.
#define COOLANT_MIST_DDR    DDRF
#define COOLANT_MIST_PORT   PORTF
#define COOLANT_MIST_BIT    3 // MEGA2560 Analog Pin 3
#endif  

// Define user-control CONTROLs (cycle start, reset, feed hold) input pins.
// NOTE: All CONTROLs pins must be on the same port and not on a port with other input pins (limits).
#define CONTROL_DDR       DDRB
#define CONTROL_PIN       PINB
#define CONTROL_PORT      PORTB
#define RESET_BIT         3  // MEGA2560 Digital Pin 50
#define FEED_HOLD_BIT     2  // MEGA2560 Digital Pin 51
#define CYCLE_START_BIT   1  // MEGA2560 Digital Pin 52
#define SAFETY_DOOR_BIT   0  // MEGA2560 Digital Pin 53
#define CONTROL_INT       PCIE0  // Pin change interrupt enable pin
#define CONTROL_INT_vect  PCINT0_vect
#define CONTROL_PCMSK     PCMSK0 // Pin change interrupt register
#define CONTROL_MASK ((1<<RESET_BIT)|(1<<FEED_HOLD_BIT)|(1<<CYCLE_START_BIT)|(1<<SAFETY_DOOR_BIT))
#define CONTROL_INVERT_MASK CONTROL_MASK // May be re-defined to only invert certain control pins.

結論その2

これでホーミングもできるようになりましたとさ

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