ModalAI Electronic Speed Controller (ESC)
Documentation for ModalAI's high-performance, closed-loop Electronic Speed Controllers (ESCs) that use a digital interface (UART, i2c in future).
ModalAI’s Electronic Speed Controllers (ESCs) are high-performing, closed-loop speed controllers that use a digital interface (UART, i2c in future).
Brief Overview
Brushless Electronic Speed Controllers (ESCs) are devices that consist of hardware and software for controlling three-phase brushless DC (BLDC) motors. ESCs communicate with the flight controller, which instructs the ESCs how fast the motor should spin.
ModalAI’s ESCs implement the following advanced features:
- Full integration with ModalAI VOXL and Flight Core PCBs
- Bi-directional UART communication with checksum; status and fault monitoring
- Real-time status and health reporting at high update rate (100Hz+ each)
- Closed-loop RPM control for best flight performance
- LED control from flight controller via UART
Feature Comparison
 |  |  |
| Feature | ModalAI 4-in-1 ESC (M0129) | ModalAI 4-in-1 ESC (M0134) | ModalAI 4-in-1 ESC (M0138) |
|---|---|---|---|
| Nominal Input Voltage | 6.0V-16.8V (2-4S Lipo) | 6.0V-16.8V (2-4S Lipo) | 6.0V-26V (2-6S Lipo) |
| 6.0V-25.2V (2-6S Lipo) (M0134-6) | |||
| VOXL Power Output | 3.8V or 5.0V @ 5A (6A 30 sec) | ❌ | 5.0V or 3.8V @ 6A |
| Aux Power Output | 1x 3.3V / 5.0V 500mA | 1x 5.0V 500mA | 1x 3.3V/5.0V 500mA, 1x 16.8V 500mA |
| Max Continuous Current Per Motor | 20A (thermally limited, requires airflow) | 20A (thermally limited, requires airflow) | 40A (thermally limited, requires airflow) |
| Max Burst Current Per Motor | 30-40A for <1s | 40-50A for <1s | 100A for <1s |
| MCU | STM32F051K86 | STM32F051K86 | STM32F051K86 |
| MOSFET Driver | MP6531A | MP6530 (M0134-1) | MP6531A |
| MP6531A (M0134-3, M0134-6) | |||
| MOSFETs | AON7528 (N) | AON7528 (N) | TBD |
| Current Sensing | 1x 0.5mOhm + INA186 (-20A..+110A) | 4x 0.5mOhm + INA186 (-10A..+55A) | 1x 0.25mOhm + INA186 (-35A..+200A) |
| ESD signal protection | ✅ | ✅ | ✅ |
| Temperature Sensing | ✅ (internal to MCU) | ✅ (internal to MCU) | ✅ (internal to MCU + top and bottom) |
| On-board Status LEDs | ✅ 4x | ✅ 4x | ✅ 4x |
| External LEDs | 1x Neopixel LED output | 2x Neopixel LED outputs | 1x Neopixel LED output |
| Secure Bootloader | Yes (AES256) | Yes (AES256) | Yes (AES256) |
| Motor PWM Switching Frequency | 48, 24 Khz | 48, 24 Khz | 48, 24 Khz |
| Maximum RPM (6 pole pairs) | 50K+ | 50K+ | 50K+ |
| PWM control input (1-2ms) | ✅ | ✅ | ❌ |
| PWM output | ✅ 4x (shared with PWM input) | ✅ 4x (shared with PWM input) | ✅ 2x |
| Active Freewheeling | ✅ | ✅ | ✅ |
| Disable Regenerative Braking | Always enabled | Always enabled (M0134-1) | ✅ Option to disable |
| ✅ Option to disable (M0134-3, M0134-6) | |||
| Tone Generation | ✅ | ✅ | ✅ |
| Closed-loop RPM Control | Yes (10Khz) | Yes (10Khz) | Yes (10Khz) |
| Number of UART ports | 2 (2Mbit+) | 2 (2Mbit+) | 1 (2Mbit+) |
| voxl_esc UART Protocol | ✅ | ✅ | ✅ |
| UART connector type | JST GH 4-pin | Hirose DF13 6-pin | JST GH 4-pin |
| UART Cable (for VOXL2) | mcbl-00015 | mcbl-00029 | mcbl-00015 |
| Weight without wires (g) | 5.9 | 9.5 | 17.9 |
| Board Dimensions (mm) | 36.5 x 36.5 | 40.5 x 40.5 | 45.5 x 59.0 |
| Mounting Hole Size, Pattern (mm) | 2.5, 30.5 x 30.5 | 3.05, 31.0 x 33.0 | 3.05, 30.5 x 30.5 |
| Notes |
Mechanical Drawings
Other ESCs
 |  |
| Feature | ModalAI 4-in-1 ESC (M0049) | ModalAI 4-in-1 ESC (M0117) |
|---|---|---|
| Nominal Input Voltage | 6.0V-16.8V (2-4S Lipo) | 6.0V-16.8V (2-4S Lipo) |
| Aux Power Output | 1x 4.5V, 1x 5.0V (adj) 600mA each | 1x 5.0V (adjustable) 600mA |
| Max Continuous Current Per Motor | 20A (thermally limited) | 20A (thermally limited) |
| Max Burst Current Per Motor | 40-50A (requires airflow and heat-spreader) | 40-50A (requires airflow and heat-spreader) |
| MCU | STM32F051K86 | STM32F051C6U6 |
| MOSFET Driver | MP6530 | MP6530 (M0117-1) |
| MP6531A (M0117-3) | ||
| MOSFETs | AON7528 (N) | AON7528 (N) |
| Individual Current Sensing | 4x 1mOhm + INA186 | 4x 0.5mOhm + INA186 |
| ESD signal protection | ✅ | ✅ |
| Temperature Sensing | ✅ | ✅ |
| On-board Status LEDs | ✅ | ✅ |
| External LEDs | Neopixel LEDs | N/A |
| Secure Bootloader | Yes (AES256) | Yes (AES256) |
| PWM Switching Frequency | 48, 24 Khz | 48, 24 Khz |
| Maximum RPM (6 pole pairs) | 50K+ | 50K+ |
| PWM control input | ✅ | ✅ |
| Active Freewheeling | ✅ | ✅ |
| Disable Regenerative Braking | ❌ Always enabled | ❌ Always enabled (M0117-1) |
| ✅ (M0117-3) | ||
| Tone Generation | ✅ | ✅ |
| Closed-loop RPM Control | Yes (10Khz) | Yes (10Khz) |
| Number of UART ports | 2 (2Mbit+) | 2 (2Mbit+) |
| voxl_esc UART Protocol | ✅ | ✅ |
| Weight without wires (g) | 9.5 | 9.5 |
| Board Dimensions (mm) | 40.5 x 40.5 | 40.5 x 40.5 |
| Mounting Hole Size, Pattern (mm) | 3.05, 31.0 x 33.0 | 3.05, 31.0 x 33.0 |
| Notes | limited availability | limited availability |
VOXL Mini 4-in-1 ESC Datasheet
M0129 and M0134 mini 4-in-1 ESCs for vehicles under 750 g: specifications and pinouts.
VOXL FPV ESC 4-in-1 Datasheet
M0138 high-current 4-in-1 ESC for FPV racing applications: specifications and pinouts.
PX4 Integration
Configure PX4 on VOXL 2, VOXL Flight, or Flight Core to drive VOXL UART ESCs.