USE_MSP_RC_OVERRIDE / INAV example

Overview

This golang program exercises INAV's MSP SET_RAW_RC with USE_MSP_RC_OVERRIDE.

Prerequisites

• A supported FC with a modern INAV (say > 4.0)

• Firmware built with USE_MSP_RC_OVERRIDE (un-comment in src/main/target/common.h or append to src/main/target/TARGET_NAME/target.h).

• The flight mode MSP RC Override is asserted

• The override mask msp_override_channels is set for the channels to be overridden.

Caveats

• For firmware earlier than INAV 7.0 (prior to 25 May 2023), it is necessary to remove the erroneous _Static_asset from src/main/cms/cms_menu_osd.c c. line 333. See PR for details.
• The bits in the bit mask count from zero, while (most) humans count channels from 1. Thus, (in the example that follows), if you wished to override channel 14, it is necessary to set bit 13 in the override mask set msp_override_channels = 8192.
• If you stop overriding the channel, it will fall back to the TX RC value.

Building

• Clone this repository
• Build the test application

make

This should result in a msp_setoverride application.

Usage

Usage of msp_setoverride [options] chan=value ...
  -b int
    	Baud rate (default 115200)
  -d string
    	Serial Device
  -every int
    	Refresh (ms) (default 100)

Channel and values

Zero or more channel:value pairs may be specified. If none are specified, the channel values are reported.

• Setting channel 14,(with set msp_override_channels = 8192), using the SITL and fl2sitl emulating an IBUS TX.

    msp_setoverride -d tcp://localhost:5760 14=1234

• Multiple channels may be set, for example, channels 14 and 15, with set msp_override_channels = 24576

    msp_setoverride -d tcp://localhost:5760 14=1234 15=1867

Refresh

The -every MS option sets the rate at which the override is sent. The default is 100ms (10hz). A minimum refresh of 5Hz is required:

• -every 200 : works, channel(s) are overridden
• -every 201 : fail(safe), channel(s) not are overridden

Device name

• On Linux, /dev/ttyUSB0 and /dev/ttyACM0 are automatically detected, on other platforms, the device node must be specified (e.g. -d /dev/cuaU0, -d COM17).
• On all platforms, TCP/IP may be used (e.g. with the INAV SITL). This takes the form of a pseudo-URI, for example -d tcp://localhost:5760
• On Linux, Bluetooth addresses may be used -d 35:54:16:36:23:98 (and more generally, device nodes -d /dev/rfcomm4, -d COM23)

Example

In this example, a emulated (SITL) IBUS receiver is configured as UART3. MSP is configured for UART 1 and 2. We use UART1 (-d tcp://localhost:5760). The SITL is armed (it is "flying" a blackbox log).

Note that msp_setoverride sends channel value 1759 for all channels other than those overridden, just to make the data obvious.

msp_setoverride -d tcp://localhost:5760 14=1234
2023/05/25 14:03:02 Using device localhost
INAV v7.0.0 SITL (69bd3e9d) API 2.5
"BENCHYMCTESTY"
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1234 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1234 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1234 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1234 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1234 1001 1001 1001 1001 armed (2c)
Tx: 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1759 1234 1759 1759 1759 1759
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1234 1001 1001 1001 1001 armed (2c)
^C

In the received data, we see that all channel values are those set by the SITL (1500, 1371, 1001, 1800), other than channel 14, which is set to the override value of 1234. Note that this takes a number of cycles to be established, as a continuous 5Hz rate is required.

MSP_RC always returns the first four channels as AERT, so AER are centred at 1500 and the throttle is 1371.

If we stop sending the override data, channel 14 falls back to the RC value of 1001. At no time, does the FC use the 1759 value, as this is outside the override mask.

### No channels, just report values and status ####
$ msp_setoverride -d tcp://localhost:5760
2023/05/25 14:03:07 Using device localhost
INAV v7.0.0 SITL (69bd3e9d) API 2.5
 "BENCHYMCTESTY"
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)
Rx: 1500 1500 1500 1371 1001 1001 1001 1001 1001 1800 1001 1001 1001 1001 1001 1001 armed (2c)

Note that the 1800 received value is set by the SITL (for RTH in this BBL/FC configuration).

Other references

• More comprehensive MSP_SET_RAW_RC example

Licence

Whatever approximates to none / public domain in your locale. 0BSD (Zero clause BSD) if an actual license is required by law.