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Merge pull request #79 from firmata/stepper-2-revisions
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updates to stepper 2.0 proposal based on comments
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@soundanalogous
soundanalogous committed Jan 12, 2017
2 parents ab42c59 + c2a5568 commit 7879e7c
Showing 1 changed file with 96 additions and 39 deletions.
135 changes: 96 additions & 39 deletions stepper-2.0.md
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ Protocol
6 num steps-per-revolution LSB
7 num steps-per-revolution MSB
8 maxSpeed LSB
9 maxSpeed MSB
9 maxSpeed MSB
10 motorPin1 or directionPin number (0-127)
11 motorPin2 or stepPin number (0-127)
12 [when interface >= 0x0110000] motorPin3 (0-127)
Expand All @@ -59,42 +59,69 @@ Protocol
```
0 START_SYSEX (0xF0)
1 Stepper Command (0x62)
2 stop command (0x01)
2 zero command (0x01)
3 device number (0-9)
4 END_SYSEX (0xF7)
```

**Stepper step**
**Stepper step (relative move)**

Position is specified as a 32-bit signed long.

The speed value is a float composed of a 23-bit significand (mantissa) and a 4-bit exponent
(biased -18 with an explicit 1's bit) and a sign bit.

|27 |26-23 |22-0 |
|-----|--------|-----------|
|sign |exponent|significant|
|1 bit|4 bits |23 bits |


```
0 START_SYSEX (0xF0)
1 Stepper Command (0x62)
2 step command (0x02)
3 device number (0-9)
4 direction (0-1) (0x00 = CW, 0x01 = CCW)
5 num steps byte1 LSB
6 num steps byte2
7 num steps byte3 MSB (21 bits (2,097,151 steps max))
8 num speed LSB (steps per second)
9 num speed MSB
10 END_SYSEX (0xF7)
4 num steps, bits 0-6
5 num steps, bits 7-13
6 num steps, bits 14-20
7 num steps, bits 21-27
8 num steps, bits 28-32
9 speed, bits 0-6 (steps per second)
10 speed, bits 7-13
11 speed, bits 14-20
12 speed, bits 21-28
13 END_SYSEX (0xF7)
```

**Stepper to**
**Stepper to (absolute move)**

Sets a stepper to a desired position based on the number of steps from the zero position.
Position is specified as a 32-bit signed long.

The speed value is float composed of a 23-bit significand (mantissa) and a 4-bit exponent
(biased -18 with an explicit 1's bit) and a sign bit.

|27 |26-23 |22-0 |
|-----|--------|-----------|
|sign |exponent|significant|
|1 bit|4 bits |23 bits |

```
0 START_SYSEX (0xF0)
1 Stepper Command (0x62)
2 to command (0x03)
3 device number (0-9)
4 num target byte1 LSB
5 num target byte2 MSB
6 speed LSB (steps per second)
7 speed MSB
8 [optional] accel LSB (acceleration in steps/sec^2)
9 [optional] accel MSB
10 [optional] decel LSB (deceleration in steps/sec^2)
11 [optional] decel MSB
12 END_SYSEX (0xF7)
4 num steps, bits 0-6
5 num steps, bits 7-13
6 num steps, bits 14-20
7 num steps, bits 21-27
8 num steps, bits 28-32
9 speed, bits 0-6 (steps per second)
10 speed, bits 7-13
11 speed, bits 14-20
12 speed, bits 21-27
13 END_SYSEX (0xF7)
```

**Stepper enable**
Expand All @@ -103,8 +130,8 @@ Sets a stepper to a desired position based on the number of steps from the zero
1 Stepper Command (0x62)
2 enable command (0x04)
3 device number (0-9)
4 device state (HIGH | LOW)
4 END_SYSEX (0xF7)
4 device state (HIGH : enabled | LOW : disabled)
5 END_SYSEX (0xF7)
```

**Stepper stop**
Expand All @@ -116,19 +143,27 @@ Sets a stepper to a desired position based on the number of steps from the zero
4 END_SYSEX (0xF7)
```

**Stepper report position (sent when a move completes or stop is called)**
**Stepper report position**

Sent when a move completes or stop is called. Position is reported as a 32-bit signed long.

```
0 START_SYSEX (0xF0)
1 Stepper Command (0x62)
2 stop reply command (0x06)
3 device number (0-9)
4 position byte 1 LSB
5 position byte 2 MSB
6 END_SYSEX (0xF7)
4 position, bits 0-6
5 position, bits 7-13
6 position, bits 14-20
7 position, bits 21-27
8 position, bits 28-32
9 END_SYSEX (0xF7)
```

**Stepper limit**

When a limit pin (digital) is set to its limit state, movement in that direction is disabled.

```
0 START_SYSEX (0xF0)
1 Stepper Command (0x62)
Expand All @@ -142,19 +177,32 @@ When a limit pin (digital) is set to its limit state, movement in that direction
```

**Stepper set acceleration**
Sets the acceleration/deceleration in steps/sec^2.

Sets the acceleration/deceleration in steps/sec^2. The accel value is composed of a 23-bit
significand (mantissa) and a 4-bit exponent (biased -18 with an explicit 1's bit) and a sign bit.

|27 |26-23 |22-0 |
|-----|--------|-----------|
|sign |exponent|significant|
|1 bit|4 bits |23 bits |


```
0 START_SYSEX (0xF0)
1 Stepper Command (0x62)
2 set acceleration command (0x08)
3 device number (0-9) (Supports up to 10 motors)
4 accel LSB (acceleration in steps/sec^2)
5 accel MSB
6 END_SYSEX (0xF7)
4 accel, bits 0-6 (acceleration in steps/sec^2)
5 accel, bits 7-13
6 accel, bits 14-20
7 accel, bits 21-28
8 END_SYSEX (0xF7)
```

**MultiStepper configuration**

Stepper instances that have been created with the stepper configuration command above can be added to a multiStepper group. Groups can be sent a list of devices/positions in a single command and their movements will be coordinated to begin and end simultaneously. Note that multiStepper does not support acceleration or deceleration.

```
0 START_SYSEX (0xF0)
1 Stepper Command (0x62)
Expand All @@ -181,12 +229,15 @@ Stepper instances that have been created with the stepper configuration command
2 multi to command (0x21)
3 group number (0-127)
4 member number (0-9)
5 num member target byte1 LSB
6 num member target byte2 MSB
5 num steps, bits 0-6
6 num steps, bits 7-13
7 num steps, bits 14-20
8 num steps, bits 21-27
9 num steps, bits 28-32
*Optionally repeat 4 through 6 for each device in group*
*Optionally repeat 4 through 9 for each device in group*
33 END_SYSEX (0xF7)
63 END_SYSEX (0xF7)
```

**MultiStepper stop**
Expand All @@ -198,17 +249,23 @@ Stepper instances that have been created with the stepper configuration command
4 END_SYSEX (0xF7)
```

**MultiStepper report positions (sent when a move completes or stop is called)**
**MultiStepper report positions**

Sent when a move completes or stop is called.

```
0 START_SYSEX (0xF0)
1 Stepper Command (0x62)
2 multi stop reply command (0x24)
3 group number (0-127)
4 member number (0-9)
5 device 0 position byte 1 LSB
6 device 0 position byte 2 MSB
5 position, bits 0-6
6 position, bits 7-13
7 position, bits 14-20
8 position, bits 21-27
9 position, bits 28-32
*Optionally repeat 4 through 6 for each device in group*
*Optionally repeat 4 through 9 for each device in group*
33 END_SYSEX (0xF7)
63 END_SYSEX (0xF7)
```

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