ArduPilot onboard OSD using an external SPI OSD breakout board

vierfuffzig · December 3, 2018, 10:20pm

Using the ArduPilot onboard OSD is possible on board types that have an external SPI port accessible, including Pixhawk. All it requires is a MAX7456 type OSD SPI breakout board like this:
http://www.hobbytronics.co.uk/max7456-osd-breakout
and a few lines added in the respective board’s hwdef.

All OSD code processing is done onboard your flightcontroller. There’s no firmware processing for the OSD board required as it only carries the video chip circuitry. OSD settings handling is done via parameters just like with onboard OSD type hardware.

I have added OSD hardware to a revomini board using the SPI pins accessible on OPLink port:

@Rolf has done this on a pixhawk (fmuv3):

required changes to hwdef are:

adding the respective CS pin define
adding the OSD to the SPI device table
setting the OSD active and making the build system add the required font binaries:

see onboard OSD type flight controllers’ hwdefs for reference.

there might be other solutions coming up to support external backends to ArduPilot OSD on hardware without video overlay chipsets. this one imho is fairly easy to do on current code base and adds a noticeable amount of convenience and functionality compared to using 328p type standalone OSD hardware.

cheers, basti.

james_pattison · December 4, 2018, 12:29pm

Basti I think you just saved a uart for a lot of people!
I didn’t know those breakouts existed!
@tridge this might be a reasonable default for external spi buses (or a good enough excuse to parametise spi)…

sergbokh · December 5, 2018, 8:16pm

Are the LOS and RESET wires required to be connected too?

vierfuffzig · December 5, 2018, 8:24pm

no, besides 5V and GND it needs the SPI pins only (CS, SCK, MOSI, MISO).

Rolf · December 5, 2018, 8:31pm

Here is the wiring Pixhawk <-> Hobbytroic-Breakout
( https://www.hobbytronics.co.uk/max7456-osd-breakout )

Rolf

Hugues · December 8, 2018, 8:15pm

Where here the extra code required to run in the autopilot for this to work ?

vierfuffzig · December 8, 2018, 10:51pm

in respective board’s hwdef

define the CS pin on the external SPI port. on fmuv3 for example:
PE4 OSD_CS CS
add osd to SPI device table. on fmuv3 external SPI is SPI4. set ID, mode and speed:
SPIDEV osd SPI4 DEVID1 OSD_CS MODE0 10*MHZ 10*MHZ
add defines to set OSD active and include font binaries
define OSD_ENABLED ENABLED
ROMFS_WILDCARD libraries/AP_OSD/fonts/font*.bin

cheers, basti

sergbokh · December 17, 2018, 4:45pm

If that could be useful for someone, The SPI4 definition and wiring for PixRacer
(But this is not tested yet, waiting for OSD breackout board to arrive)

vierfuffzig · December 20, 2018, 7:24pm

all those minimOSD boards catching dust didn’t let me rest, so i tried to modify an airbot microOSD and access the videochip’s SPI. i actually found that the airbot microOSD (the one i prefereably used as a standalone for the AB7456’s stability and low power consumption) does have SCK, MISO and MOSI exposed as solder-pads:

that’s pretty cool as it reduces delicate solderjobs to the CS pin. that’s pin 8 on the 7456 chip, connected to pin 10 (=PD6) on the 328p. so i took the atmega off:

the solder pads for SCK, MISO and MOSI can be routed to the UART pinheader pads that are not in use anymore without too much hassle. i then added an additional pin on the input side to connect CS to:

…aaaaand here’s my refurbished $5 32bit minimOSD:

cheers, basti.

sergbokh · January 3, 2019, 11:39pm

Can’t get my Hobbytronics OSD breakout board to work with PixRacer.
Connected as I’ve described in my post above.

My hwdef change is https://github.com/SergeyBokhantsev/ardupilot/commit/317405f5e42273f77880162ac769ea921a0107a9

Firmware built and uploaded OK. Have set OSD_TYPE = 1 in my parameters.

I have a picture from my camera, but no any OSD text.

@vierfuffzig may be you will have a chance to look at my hwdef. Thought not sure if this a wiring or firmware problem. Any advice will be appreciated!

sergbokh · January 4, 2019, 12:51am

Ah, looks like I can only use “osd” name but not any free name in the definition:
SPIDEV osd SPI4 DEVID1 EXTSPI_CS MODE0 10MHZ 10MHZ

because it is hardcoded here:

github.com

ArduPilot/ardupilot/blob/bba3546279e5cf4558a4b313a9c3203dafa05433/libraries/AP_OSD/AP_OSD.cpp#L167


}


void AP_OSD::init()
{
switch ((enum osd_types)osd_type.get()) {
case OSD_NONE:
default:
    break;


case OSD_MAX7456: {
    AP_HAL::OwnPtr<AP_HAL::Device> spi_dev = std::move(hal.spi->get_device("osd"));
    if (!spi_dev) {
        break;
    }
    backend = AP_OSD_MAX7456::probe(*this, std::move(spi_dev));
    if (backend == nullptr) {
        break;
    }
    hal.console->printf("Started MAX7456 OSD\n");
    break;
}

Will try that.

vierfuffzig · January 4, 2019, 8:23am

@sergbokh did you get it to work? as you wrote too i do suppose the OSD_CS is required as well as adding the osd to the SPI device table:

github.com

vierfuffzig/ardupilot/blob/9f0d15aa38674f73dd4444fc81c8ee32c5651214/libraries/AP_HAL_ChibiOS/hwdef/revo-mini/hwdef.dat#L139n


define HAL_BARO_DEFAULT HAL_BARO_MS5611_I2C
define HAL_BARO_MS5611_I2C_BUS 0
define HAL_BARO_MS5611_I2C_ADDR 0x77


# also allow for probing of external barometers
define HAL_PROBE_EXTERNAL_I2C_BAROS


# SPI devices
SPIDEV mpu6000   SPI1 DEVID1 MPU_CS   MODE3 1*MHZ 8*MHZ 
SPIDEV dataflash SPI3 DEVID1 FLASH_CS MODE3 1*MHZ 8*MHZ
SPIDEV osd       SPI3 DEVID2 OSD_CS MODE0 10*MHZ 10*MHZ


# 8 PWM available by default
define BOARD_PWM_COUNT_DEFAULT 8


define OSD_ENABLED ENABLED


#font for the osd
ROMFS_WILDCARD libraries/AP_OSD/fonts/font*.bin

cheers, basti.

sergbokh · January 4, 2019, 8:49am

Yes, all works great! The only problem was the SPIDEV name, as I wrote above.
Also I’ve set 2MHZ just for a case, because there is a relatively long wires. This seems didn’t affect anything.

vierfuffzig · January 4, 2019, 11:16am

nice, congrats! seems i missed your last post reg. device table, sorry.

basti.

ucaszzw · January 8, 2019, 7:54am

How do I determine the correct DEVID when I change the SPI table?@vierfuffzig @sergbokh
In fact, I hope to configure a spi port on the pixracer for optical flow.

sergbokh · January 8, 2019, 8:26am

I may be wrong but for SPI devices I believe DEVID just need to be an unique number on the SPI bus. So if there is only device on SPI4 bus then DEVID1 should be OK.

vierfuffzig · January 8, 2019, 8:59am

@ucaszzw @sergbokh that’s how i did it too, successfully so far. just choose a unique identifier on the respective bus.

cheers, basti.

kalalaa · August 4, 2019, 2:28pm

Hi!

I am new here, and i am new in ardupilot. I have a pixhawk 1 with six blheli_32 esc’s. The telemetry works great, but i want to see the esc’s current on osd. I ordered a MAX7456 breakout board, and connected it to SPI port. But how will it work? I dont’t know what is hwdef, or how can i modify it. Please can somebody write a step by step guide for me?

Thanks!
Laszlo

vierfuffzig · August 4, 2019, 3:11pm

@kalalaa as for now adding an external SPI OSD backend to pixhawk type hardware requires individual changes to the respective board’s hardware definition file (hwdef) and compiling a customized firmware.
this http://ardupilot.org/dev/index.html is the best place to start for setting up a build environment.

on a sidenote, there’s a PR pending for adding the ext. SPI OSD defines to fmuv3 default firmwares. it’ll need some more effort from my side to get a decision if it adds any value though… https://github.com/ArduPilot/ardupilot/pull/11259

cheers, basti.