NxtPX4

We are now supporting PX4 1.14.x firmware！ Check compile section for more information

All GPIO & function small size PX4 for UAV research for HKUST UAV-Group

Dimension of NxtPX4: 27mmx32mmx8mm

Hardware quick review

UART	TTY	SerialName	Suggest Funcion
USART1	/dev/ttyS0	SERIAL_GPS1	AUX
USART2	/dev/ttyS1	SERIAL_GPS2	AUX
USART3	/dev/ttyS2	SERIAL_TEL1	ESC report (not recommend to use because it serves as debug console)
UART4	/dev/ttyS3	SERIAL_TEL2	Connect with offboard computer
UART5	/dev/ttyS4	SERIAL_RC	Receiver
UART7	/dev/ttyS5	SERIAL_TEL3	AUX

Getting start

Use precompiled bootloader and firmware

please check firmware dir

Compile locally

1. clone repo.
2. run init repo script: ./init_all_repo.sh it will take some time to clone all submodules into loccal
3. Enter directory NxtPX4-Hardware: cd ./NxtPX4-Hardware you should notice that you are not on main branch, So Checkout to main branch using: git checkout -b main
4. cd back to NXTPX4 dir
5. Enter directory PX4-Autopilot: cd ./PX4-Autopilot you should notice that you are not on main branch or develop branch. So checkout main branch to local and then checkout to develop branch to compile frameware for NxtPX4. git checkout -b main and then git checkout -b develop origin/develop
6. configure done !

Setting up NxtPX4

Notice!

We found a silkscreen printing error on the USART 1 and 2 of the V1.2.3 PCB. The labels for Tx and Rx are incorrect. Please follow the silk screen in the modified version V1.2.3.1(picture below)

The only difference between v1.2.3 and v.1.2.3.1 is the silkscreen of USART1 and USART2

(connection for v1.2.3)

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Basic connection with receiver & ESC & computer

If your receiver uses Sbus please connect the pads in red circle

Compile PX4Firmware

Using make

Note！！！

For PX4 1.14.x firmware please use branch develop_v1.14.x. I am manually merging with the latest main branch from PX4.

1. go to PX4-Autoplilot directory
2. using make hkust_nxt_bootloader to compile bootloader. For develop_v1.14.x use make hkust_nxt-v1_bootloader
3. Press boot button on board and then connect it with computer, flash bootloader with Betaflight configurator or STM32programmer
4. using make hkust_nxt to compile firmware, and flash .px4 through QGC. . For develop_v1.14.x use make hkust_nxt-v1

Using Docker

Usage:    ./docker_build.sh <branch_name> <frameware_name>

1. compile firmware ./docker_build.sh develop_v1.14.x hkust_nxt-v1
2. compile bootloader ./docker_build.sh develop_v1.14.x hkust_nxt-v1_bootloader

PX4 Configuration settings

Power

Set power_source Power Module, then calibrate voltage and current analog data

Receiver

Set RC_PORT_CONFIG with Radio controller

MAVLink

Set MAV_0_CONFIG with TELEM 2

HIGH_RES_IMU and High frequency /imu/data

create file in your tf-card /etc/extras.txt

mavlink stream -d /dev/ttyS3 -s ATTITUDE -r 200

mavlink stream -d /dev/ttyS3 -s HIGHRES_IMU -r 1000

then using the following settings

IMU_GYRO_RATEMAX: 2000Hz

IMU_INTEG_RATE: 400Hz

MAV_0_MODE: External vision

Set Uart4 to 921600

MAV_0_RATE 92160B/s

after these settings you will have approximate 500Hz /imu/data_raw /imu/data

if you want to have presice 500Hz imu/data_raw and 200Hz imu/data

SYS_MC_EST_GROUP: Q attitude estimator

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Hardware development

• Kicad 7.0 required
• Create new branch for your own features
• Only general hardware features can be merged into main branch

Caution!!!!!!!!

in v1.0.1 design, the original idea is to make ESC connector order weird, to make user notice the PINOUT sequence, however in practice, Rx pin is too close to Vbat pin, which leads to MCU damage at the moment power on or off if the cable is not titely installed. Noticing that, in v1.1.0 design, we change the ESC pinout order.

Frameware development

Pre-build firmware and bootloader

The pre-build firware and bootloader are in ./firmware dir, donwload and flash in corresponding with your hardware version

Compile

Local compilation

• Frameware compile: make hkust_nxt
• bootloader compile: make hkust_nxt_bootloader

Containerized compilation (recommended)

Build a specific version of PX4 firmware using docker container.

Usage:    ./docker_build.sh <branch_name> <frameware_name>
Example:  ./docker_build.sh develop_v1.14.x hkust_nxt-v1
          ./docker_build.sh develop_v1.14.x hkust_nxt-v1_bootloader

Develop

• Create new branch named as feature-xxx(feature info) from develop branch to start your own feature development
• After test your own feature, mereged into develop branch and push a pull request (only general features will be accepted)

update repo using script: ./update_all_repo.sh

TODO

• Develop branch back to normal HIGHRES_IMU
• ~~remove MPU6500 ~~
• replace 0420 Inductor with 05xx inductor
• refine pinout (v2.0 hardware)

Troubleshooting

TODO

1. ESC RPM report cannot run with MAVRos /mavros/imu/data

Maybe V2.0-Dual

1. Dual BMI 088