VOXL 2 Power
Power input on J4, the VOXL Power Module v3, and battery status in PX4.
Table of contents
Hardware
J4 - Main 5VDC Input with I2C
The main power input is J4 and is typically paired with a VOXL Power Module v3, which provides the up to 6A momentary inrush current and provides two I2C based power monitoring ICs, providing PX4 the battery status.
The recommended cable is MCBL-00001 for this interface.
M0054 J19:
- Connector on board : SM12B-GHS-TB(LF)(SN)
- Mating connector : GHR-12V-S
5V Rail Tolerance
A droop of roughly 200 mV on VDC_5V_LOCAL and VDC_5V_LOCAL_USB1 under load (for example while a ToF sensor is ranging) is within the normal operating margin of the 5 V rail and is not a supply problem. A transient of that size is more likely localized contact or pin loss at a connector than a bulk supply issue. The eFuse on this rail does not assert until approximately 4.4 V, so a 200 mV droop from 5 V is nowhere near that threshold. Downstream logic is regulated from a 3.8 V VBAT rail that has margin well above the minimum needed, and that rail is permitted to droop past 3.3 V before any real issue occurs. A droop of this size is not a cause of RC dropouts. The power stage of the M0129 VOXL Mini ESC is proven to the same load capability and test rigor as the standalone M0041 power module, using the same parts.
Software
Checking Battery Status
With the VOXL PM attached, you check the battery using px4-listener battery_status command after getting a shell to VOXL 2.
Here’s an example from a 3S battery:
px4-listener battery_status
TOPIC: battery_status
battery_status_s
timestamp: 1080175258 (0.059704 seconds ago)
voltage_v: 12.6662
voltage_filtered_v: 12.6659
current_a: 0.1758
current_filtered_a: 0.1791
average_current_a: 0.0000
discharged_mah: 51.6742
remaining: 1.0000
scale: 1.0000
temperature: nan
cell_count: 3
voltage_cell_v: [4.1200, 4.3200, 4.2200, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000]
max_cell_voltage_delta: 0.0000
capacity: 0
cycle_count: 0
run_time_to_empty: 0
average_time_to_empty: 0
serial_number: 0
manufacture_date: 0
state_of_health: 0
max_error: 0
interface_error: 0
connected: True
source: 0
priority: 0
id: 1
is_powering_off: False
warning: 0
voxlpm PX4 Driver
The voxlpm PX4 driver monitors both battery and companion computer regulated voltage.
The driver runs in PX4 on the DSP, and interfaces through SSC QUP2.
You can’t get to this I2C bus through Ubuntu at this time.