Hardware Configuration

Before building and flashing the firmware you must review and possibly adjust the hardware configuration.

Here is a short checklist of things to consider:

What flight controller board will you be using? Several boards are supported.
What type of receiver will you be using?
- On-board SPI AFHDS/AFHDS2A is available when using the "HappyModel Crazybee F4 Lite 1S" flight controller as found on the Mobula6 (this is a MATEKF411RX target board) and also with the CRAZYBEEF3FS target.
- External SPI Bayang is available using various transceiver modules..
  - I've had great success with the Play F4 board and an NRF24L01. That board also works quite well with XN297L modules harvested from toy transmitters.
Configure your aux channels: throttle kill switch (similar to an arm switch), level mode enable/disable, turtle mode, motor beeps, etc
Will you be using RPM filtering?
- If so, you'll want to make sure your ESCs are flashed with either JESC, JazzMaverick or Bluejay.

Specifying the flight controller

Several flight controller targets are currently supported (MATEKF411RX, CRAZYBEEF3FS, NOX, OMNIBUSF4). The MATEKF411RX target can support an on-board SPI transceiver (only FlySky AFHDS/AFHDS2A is supported at this time). The CRAZYBEEF3FS target also supports on-board SPI FlySky AFHDS/AFHDS2A.

I'm actively using many of these target boards for my whoops and micros with the exception of the OMNIBUSF4, that target was only used for development as it provides SWD solder pads. Support for the OMNIBUS (F3 processor) board was started but has yet to be completed.

You will not need to edit any source files to specify your target board. Instead you just need to make note of the target name (such as NOX or MATEKF411RX). You'll need to know this when you build the firmware as described in the Develop section of this document.

Specifying the receiver

If you wish to use an external SPI RX transceiver 4 different modules are supported. IBUS support is also available; I've successfully used the FlySky FS-RX2A receiver with IBUS on the NOX and OMNIBUSF4 targets. And if you're using that Mobula6 board or the CrazyBeeF3FS board then you can use the on-board SPI AFHDS/AFHDS2A receiver.

You will edit the _my_config.h source file to specify your receiver option. Using a text editor (I suggest Visual Studio Code) open the file and look near the top of the file for something that looks like this:

//------------------------------------------------------------------------------
// RX protocol and configuration
// Enable only one of the following defines
//------------------------------------------------------------------------------
//#define RX_SILVERLITE_BAYANG_PROTOCOL   // Enable SilverLite SPI Transceiver RX implementation
//#define RX_IBUS // Enable IBUS protocol support on a USART RX pin, double-check rx_ibus.cpp and define one of: FLYSKY_i6_MAPPING, TURNIGY_EVOLUTION_MAPPING
//#define RX_FLYSKY     // Enable FlySky (AFHDS) SPI transceiver implementation
#define RX_FLYSKY2A   // Enable FlySky (AFHDS-2A) SPI transceiver implementation

The lines that start with // are "commented out", meaning they don't do anything. You basically want to comment out 2 of the 3 choices. The example above enables the FlySky (AFHDS/AFHDS2A) SPI transceiver option. If instead you want to use an external RX module with IBUS protocol then you'd edit that text to look like this intead:

//------------------------------------------------------------------------------
// RX protocol and configuration
// Enable only one of the following defines
//------------------------------------------------------------------------------
//#define RX_SILVERLITE_BAYANG_PROTOCOL   // Enable SilverLite SPI Transceiver RX implementation
#define RX_IBUS // Enable IBUS protocol support on a USART RX pin, double-check rx_ibus.cpp and define one of: FLYSKY_i6_MAPPING, TURNIGY_EVOLUTION_MAPPING
//#define RX_FLYSKY     // Enable FlySky (AFHDS) SPI transceiver implementation
//#define RX_FLYSKY2A   // Enable FlySky (AFHDS-2A) SPI transceiver implementation

If you choose the RX_SILVERLITE_BAYANG_PROTOCOL option (an external SPI transceiver module configured to run Bayang protocol), then it would look like the snippet below, plus you'll also want to review and possibly edit the text immediately below that.

//------------------------------------------------------------------------------
// RX protocol and configuration
// Enable only one of the following defines
//------------------------------------------------------------------------------
#define RX_SILVERLITE_BAYANG_PROTOCOL   // Enable SilverLite SPI Transceiver RX implementation
//#define RX_IBUS // Enable IBUS protocol support on a USART RX pin, double-check rx_ibus.cpp and define one of: FLYSKY_i6_MAPPING, TURNIGY_EVOLUTION_MAPPING
//#define RX_FLYSKY     // Enable FlySky (AFHDS) SPI transceiver implementation
//#define RX_FLYSKY2A   // Enable FlySky (AFHDS-2A) SPI transceiver implementation

//------------------------------------------------------------------------------
// When using RX_SILVERLITE_BAYANG_PROTOCOL you must specify which transceiver
// module you're using and whether or not you're using 3-wire SPI or 4-wire SPI.
//
// Note:  The software SPI pins used for interfacing with the module are defined 
// in file: trx_spi_config.h
//------------------------------------------------------------------------------
#ifdef RX_SILVERLITE_BAYANG_PROTOCOL

// Define only one of the TRX_??? values below
#define TRX_NRF
//#define TRX_XN297
//#define TRX_XN297L
//#define TRX_LT8900

See the line that says // Define only one of the TRX_??? values below? You'll do something similar here, you'll comment out 3 of the 4 choices. The snippet above has enabled only the TRX_NRF option. This means you'll be using an NRF24L01 transceiver module for your receiver (and also to transmit back telemetry).

Configuring SPI

When using an external SPI transceiver module you will want to review the pin assignments that connect the STM32 processor to your external module.

Examine the trx_spi_config.h header file and it should be commented well enough to figure out how things are hooked up and how you can change things if needed.

The Play F4 and NRF24L01 section provides a pretty good walkthru of how to connect an NRF24L01 module to a "Play F4" flight controller board.

Configuring Rates and Expo

The next section of the _my_config.h file is where you'll define your rates and expo.

//------------------------------------------------------------------------------
// Rates
//------------------------------------------------------------------------------

// rate in deg/sec for acro mode
#define MAX_RATE            800
#define MAX_RATEYAW         675

#define LEVEL_MAX_ANGLE     80
#define LEVEL_MAX_RATE      900

#define LOW_RATES_MULTI     0.65

//------------------------------------------------------------------------------
// Expo
//  Allowed values are 0.00 to 1.00. A value of 0 means no expo applied
//  The higher the value, the less sensitive near center
//------------------------------------------------------------------------------

#define ACRO_EXPO_ROLL      0.85
#define ACRO_EXPO_PITCH     0.85
#define ACRO_EXPO_YAW       0.26

#define ANGLE_EXPO_ROLL     0.55
#define ANGLE_EXPO_PITCH    0.55
#define ANGLE_EXPO_YAW      0.30

Configuring PID terms

The next section in _my_config.h is where you'll define your PID terms for acro and angle (level) modes.

//------------------------------------------------------------------------------
// PID term overrides
//------------------------------------------------------------------------------
                        //  Roll    Pitch   Yaw
#define     ACRO_P      {   .040,   .040,   .01     };
#define     ACRO_I      {   .250,   .250,   .50     };
#define     ACRO_D      {   .035,   .035,   .0      };

// Angle mode P and D terms
#define     ANGLE_P1    10.
#define     ANGLE_D1    3.0

The values shown here are decent starting points for 65mm or 75mm whoops as well as 2.5" and 3" micros using 0802, 1102 or 1103 motors.

You can always fine tune them in the field using stick gestures and the on screen display.

TODO: Document the PID tuning feature

More and more

The rest of the _my_config.h file is where you configure even more options that are available to you. I won't go into great detail on them but here's a list of what to expect:

RPM_FILTER - If defined, this will enable RPM filtering. By default this is defined for all targets. Be sure you've already flashed your ESCs with firmware that supports RPM filtering.
LOOPTIME - By default the looptime is configured for 250us (4k loop). You really can't go higher unless you disable RPM filtering and/or overclock. This value works very well with the targets supported by SilverLite.
Various filters. Read the comments in the source file for more info
Switches/Channels - What aux channels (switches on your transmitter) are supported and what they should do. This section is used to map 4 features (THROTTLE_KILL_SWITCH, LEVELMODE, MOTOR_BEEPS_CHANNEL and RATES) to some Bayang channels. It requires you know what Bayang channels your TX is setup to use when it transmits with the Bayang protocol.
- Note: If you're using IBUS or AFHDS/AFHDS2 protocol you will instead need to edit some code in rx_flysky.cpp or rx_ibus.cpp. I apologize in advance for not documenting this further.

Even more config

If you have need to tweak the DSHOT configuration, or motor idle offset or motor pole count then you'll want to review and edit the _myHardware.h file.