Peter Barker
472a668643
consistent headings across markdown files will allow us to make wide-spread mechanical changes to these as desired
PrincipIoT H7 Pi
The PrincipIoT H7 Pi autopilot is manufactured by PrincipIoT. It's designed to be paired with a Raspberry Pi Zero 2 for low cost onboard computing applications.
Where to Buy
PrincipIoT Website
Specifications
-
Processor
- STM32H743 32-bit processor, 480Mhz
- 2MB Flash
- 1MB RAM
-
Sensors
- Invensense ICM-42688P
- Invensense IIM-42653
- Infineon DPS368 Barometer
- ST IIS2MDC Magnetometer
-
Interfaces
- Micro SD card
- USB-C
- 9 PWM (6 motors, 2 servos, and LED strip)
- 6 UARTS, one shared with the Raspberry Pi
- CAN
- ESC Connector with current sense and telemetry inputs
- VTX Connector with UART and analog video from the Raspberry Pi
- Debug port
-
Power
- Integrated voltage/current power monitor 11V - 30V (3S - 6S) input
- 10V GPIO controlled Video power BEC, 2A output
- 5V, 2A output for board, Raspberry Pi, and peripherals
-
Dimensions
- Size: 65 x 30 x 9 mm (20mm high with Raspberry Pi installed)
- Weight: 11.3g with MicroSD card
For more information, see the PrincipIoT Wiki.
Pinout
UART Mapping
The UARTs are marked in the above pinouts. The RX pin is the receive pin for the MCU (input). The TX pin is the transmit pin for the MCU (output).
| Port | UART | Protocol | Function |
|---|---|---|---|
| SERIAL0 | USB | MAVLink2 | |
| SERIAL1 | USART2 | Unused | Debug |
| SERIAL2 | USART3 | MAVLink2 | Pi UART |
| SERIAL3 | UART4 | GPS | GPS |
| SERIAL4 | USART6 | DisplayPort | VTX |
| SERIAL5 | UART7 | ESC Telem | ESC Telem |
| SERIAL6 | UART8 | RCin | RX |
All UARTs support DMA. Any UART can change function by changing the related protocol parameter. USART3 is wired to the UART on the 40 pin Raspberry Pi header and the external UART connector. UART7 is receive only.
RC Input
The PrincipIoT H7 Pi defaults SERIAL 6 as RC input. It can be used with any ArduPilot compatible serial protocol. It does not support PPM protocols. SBUS/DSM would connect to UART8 RX input.
- FPort would require SERIAL6_OPTIONS be set to "15" and connect to the TX pin.
- CRSF would require SERIAL6_OPTIONS be set to "0" and use both RX and TX pins.
- SRXL2 would require SERIAL6_OPTIONS be set to "4" and connects only the TX pin.
Any other UART can be used for RC system connections in ArduPilot also, see RC systems for details.
PWM Output
The PrincipIoT H7 Pi controller supports up to 8 PWM outputs.
The PWM outputs are in 3 groups:
- PWM 1 - 4 in group 1 (Timer 5)
- PWM 5 & 6 in group 2 (Timer 3)
- PWM 7 & 8 in group 3 (Timer 15)
Channels within the same group need to use the same output rate. If any channel in a group uses D-Shot then all channels in the group need to use D-Shot.
All outputs are directly wired to the H743 MCU. All 8 outputs support normal PWM output formats. All outputs support DShot, outputs 1-6 support Bi-Directional DShot.
Analog Video and OSD Support
The Raspberry Pi Zero 2 support analog video output through a pad on its PCB. Installing the included POGO pin connects this pad to the H7 Pi and routes the analog video from the Raspberry Pi to the analog video pin on the VTX connector.
The SH1.0-5P connector supports a connection to a VTX. Protocol defaults to DisplayPort. Pin 1 of the connector is +10V so be careful not to connect this to a peripheral requiring 5v. DisplayPort OSD is enabled by default on SERIAL5.
VTX Power Control
GPIO 81 controls the VTX BEC output to pins marked "10V" and is included on the HD VTX connector. Setting this GPIO high turns off the voltage regulator. By default this pin is set low (regulator on) at boot and is controlled by RELAY2.
Camera Switch
GPIO 82 controls the PINIO2 GPIO pin which can be used as a camera switch or other user defined function. It defaults to low on boot.
Compass
An on-board IIS2MDC compass is provided. This compass is on the external I2C bus. Do not connect an external IIS2MDC compass or both may not be detected as they only have one address. If you need to use an external compass, use a different model or desolder the onboard one.
GPIOs
| Pin | GPIO Number | Function |
|---|---|---|
| PWM(1) | 50 | Motor |
| PWM(2) | 51 | Motor |
| PWM(3) | 52 | Motor |
| PWM(4) | 53 | Motor |
| PWM(5) | 54 | Motor |
| PWM(6) | 55 | Motor |
| PWM(7) | 60 | Servo |
| PWM(8) | 61 | Servo |
| PWM(9) | 62 | LED Strip |
| ALARM | 32 | Buzzer |
| VTX PWR | 81 | 10V BEC Enable |
| USER SW | 82 | GPIO Switch |
| LED0 | 90 | Blue LED |
| LED1 | 91 | Green LED |
Battery Monitoring
The board has a internal voltage sensor and connections on the ESC connector for an external current sensor input. The voltage sensor can handle up to 6S LiPo batteries.
The default battery parameters are:
- BATT_MONITOR = 4
- BATT_VOLT_PIN = 10
- BATT_CURR_PIN = 11 (CURR pin)
- BATT_VOLT_MULT = 11.0
- BATT_AMP_PERVLT = 40
Firmware
Firmware for the PrincipIoT H7 Pi is available from
ArduPilot Firmware Server under
the PrincipIoTH7Pi target.
Loading Firmware
To flash firmware initially, connect USB while holding the bootloader
button and use DFU to load the with_bl.hex file. Subsequent updates can
be applied using \.apj files through a ground station.