Gavan Fantom
8ca5620e5c
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3 years ago | |
|---|---|---|
| gerber | 3 years ago | |
| step32.pretty | 3 years ago | |
| .gitignore | 3 years ago | |
| README.md | 3 years ago | |
| fp-lib-table | 3 years ago | |
| step32.kicad_pcb | 3 years ago | |
| step32.kicad_pro | 3 years ago | |
| step32.kicad_sch | 3 years ago | |
| step32.kicad_sym | 3 years ago | |
| step32.pdf | 3 years ago | |
| sym-lib-table | 3 years ago | |
README.md
step32
ESP32 development board with stepper motor driver
Pin assignment
A4988 Stepper Driver
| GPIO | Signal |
|---|---|
| 12 | ~RESET |
| 13 | ~ENABLE |
| 14 | ~SLEEP |
| 16 | MS1 |
| 17 | MS2 |
| 18 | MS3 |
| 19 | DIR |
| 23 | STEP |
| 25 | DAC |
Microstepping
| Resolution | MS1 | MS2 | MS3 |
|---|---|---|---|
| Full Step | 0 | 0 | 0 |
| Half Step | 1 | 0 | 0 |
| Quarter Step | 0 | 1 | 0 |
| Eigth Step | 1 | 1 | 0 |
| Sixteenth Step | 1 | 1 | 1 |
Current limiting
The DAC pin is used to set the current limit.
The current limit is 15/23 of the DAC voltage.
| Current limit | DAC voltage |
|---|---|
| 1A | 1.533V |
| 1.5A | 2.300V |
| 2A | 3.066V |
The DAC output is not optional. It must be set correctly for the stepper driver to function.
I2C Expansion
| GPIO | Signal |
|---|---|
| 21 | SDA |
| 22 | SCL |
The I2C bus is terminated on this board. If not desired, remove R5 and R6, next to the I2C connectors.
End stops
| GPIO | Signal |
|---|---|
| 34 | END1 |
| 35 | END2 |
Note that these pins can be configured either as analogue or as digital inputs, depending on the type of end stops required.
LED
| GPIO | Signal |
|---|---|
| 2 | LED |
Motor connection
There are two connectors for the stepper motor. Only one should be used at a time. They correspond to the two most common ways of connecting bipolar stepper motor coils to a 4-pin header. The coil assignment is marked on the silkscreen by each connector for convenience.
Heat sink
The A4988 can operate at low currents without a heat sink. At higher currents (greater than 1 amp) a heat sink may be required.
Dimensions and mounting
The PCB is 55mm wide and 64mm high, excluding the antenna. The antenna sticks out by around 6mm.
The mounting holes are 47mm apart horizontally and 53mm apart vertically. They are inset 4mm from the sides and from the bottom edge. They are sized to accept M3 screws.
Power supply
This board can be powered either from an external 12 volt supply (2.5mm barrel jack), in which case a buck converter generates 3.3 volts for the ESP32, or directly from USB, in which case a linear regulator generates the 3.3 volt supply.
The motor can not be powered from USB. Only the low voltage circuit will be energised when powered by USB.
While the motor power is labelled as 12 volts, it should operate anywhere between 7 and 20 volts. Do not exceed 20 volts.