Owl Power Management
Contents
Power Connection Hardware
Goal: Connect the NUC to the 12V output source used by the Joule in the original TB3 Waffle. This is a reasonable possibility because the NUC uses an amp when lightly loaded which is well within the the 3 amp spec for power input to the Joule.
- The Joule 570x development kit
- Online Guide for the Intel® Joule™ Module Development Kit Overview
- Uses 2.1 mm inner diameter (positive)
- 5.5 mm outer diameter (negative)
- 12 v 3 amps
- Intel NUC Board D54250WYB
- Intel NUC Board D54250WYB and Intel NUC Board D34010WYB Technical Product Specification H18263-007 May 2017 page 48 (page 55 also has some information about power requirements)
- 5.5 mm outside diameter
- 2.5 mm inside diameter
- 12 - 19V
Joule Cable to NUC Adapter Cable
OpenCR 12V Supply
Goal
The question becomes whether the OpenCR can supply 12V with enough current headroom to support the NUC.
The OpenCR has two power output connectors that are physically the same but with different semantics and specifications. The documentation is ambiguous about which connector it is talking about.
OpenCR References
- OpenCR1.0 Robotis e-Manual
- Section 2 says the 12V output source can handle 4.5 amps
- TurtleBot3 Robotis e-Manual Appendix 31.2 OpenCR1.0
- Section 31.2.2 says that the board delivers 12V at 1 amp.
- Which connector
- The power source immediately to the left of the power switch is labeled 12V. I have assumed that the documentation is consistent about the 1 amp vs. 4.5 amp spec.
- However, in the OpenCR eManula the input power source and 12V output source have the same spec. I am under the impression that the connector to the immediate right of the power switch simple provides the output from the DC Adapter in (sometimes referred to as SMPS - Switch Mode Power Source). I haven't been able to locate the reference.
Cable
- I connected the Intel NUC to the OpenCR 12V out using the cable supplied with the Joule Waffle and an adapter I designed for the NUC. (The inside pin for a NUC is 2.5mm and for a Joule is 2.1mm.) This is the same power output jack that is used for the Joule.
Baseline Test
Goal is to get the baseline current used by the OpenCR when it is not powering the NUC.
- The NUC is powered by its brick.
- A bench power supply is set to 11.1 volts and connected to the 11.1 V battery input of the OpenCR.
- The lidar was connected to the NUC
| OpenCR 11.1V at Battery - Not powering NUC | |
|---|---|
| State | Current Amps |
| Off | 0 |
| Booted | 0.22 |
| NUC Booted | 0.22 |
| Post Bringup | 0.22 |
| Motors running full no load | 0.34 |
OpenCR Powered NUC
- The Intel NUC is connect to the OpenCR 12V out using the cable supplied with the Joule Waffle. The adapter describe above is used to adapt the Joule cable to the NUC.
- I connected a bench power supply to the battery input and set set it to 12 V.
- The lidar was connected to the NUC
Note: If the bench supply is set to 11.1 V the OpenCR's low voltage buzzer will go off. This didn't haven in the prevous test. I suspect there is some internal resistance someplace that is causing a voltage drop. Setting the bench power supply to 12 V solved the problem. I suspect the 11.1 V parking on the battery input label is to define the battery rating. Not the input voltage. The OpenCR expectation is to have the bench power supply connected to the SMPS (Switch Mode Power Supply input jack. However, I was interested in understanding the power requirements of the battery and the bench power supply allowed me to set the voltage and read the current draw.
| OpenCR 12.0V at Battery - plus NUC | ||
|---|---|---|
| State | Peak Amps | Steady State |
| Off | 0 | 0 |
| Booted - NUC booting - lidar turning | 1.9 | 1.8 |
| NUC Booted with lidar | 1.43 | 0.77 |
| Post Bringup | 0.9 | 0.84 |
| Post keyboard teleop | 1.45 | 0.9 |
| Motors running full no load (0.26 M/sec) | 1.03 | 0.97 |
| Powered down NUC | 0.22 | 0.22 |
Robotis Forum Question
- Can the OpenCR board's 12V output source power an Intel NUC? POST No. 2407800
OpenCR Input Power Source
LiPo Batteries
- Original Battery =
- 11.1V 3s
- Dean's connector
- 1800 mAh: Original
- My replacement *
- As above except
- 2200 mAh: 25C: Floureon replacement
Supplied Power Bricks
- TurtleBot3
- 12V at 5A (measured 12.00V with Fluke meter)
- NUC
- meaasured 19.00V Fluke meter
Vbus
Power OpenCR from NUC.
- USB-C
- USB 2.0/1.1: 5V up to 500 mA
- USB 3.0/3.1/3.2: 5V up to 900 mA
- in USB-C mode that may be 5V at either 1.5 or 3 A
LiPo Battery Notes
Voltage to capacity
- Lipo Voltage Chart: Show the Relationship of Voltage and Capacity Ampow professional blog, September 11, 2018
Key takeaway: When a 3s LiPo gets down to 11.12 volts you have 15% of its capacity left. It is recommended that you don't go below this.
General
- Li-Ion & LiPoly Batteries from Adafruit
- A Guide to Understanding LiPo Batteries
- 11 Things to Know About LiPo Batteries to Get the Best Performance, Life, Value & Fun Out of Them, Whatever You Fly.
OpenCR Low Voltage Buzzer
The low voltage buzzer goes off if set the input voltage to 11.1 V as the photo in section 3 (Layout/Pin Map) of the OpenCR eManual suggests. Setting the voltage to 12 solves this problem.
