m500 enabling RTK GPS
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Hi team,
I am wondering if m500 could enable RTK GPS by QGC settings?
If so, how could I test if RTK is enabled? (GPS drift will be reduced by viewing log?)
If not, how could I achieve RTK GPS with centimeter-level accuracy? (By adding an extra RTK receiver?)
Thanks.
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I double-check the GPS module used on m500 is HolyBro M8N. It doesn't support RTK and the GPS sampling rate seems to be 5Hz, which is a bit low accuracy for my experiments.
I am thinking if m500 could switch the GPS module to other RTK-enabled ones? I found 2 options, HolyBro M8P and F9P. Both modules can enable RTK, and M8P is about 10Hz while F9P is up to 20Hz. F9P is more satisfied with my experiment requirement.
I am wondering if m500 could easily switch to one of these by plug-in? Or I should update any GPS parameters of voxl to enable RTK after replacement?
All 3 GPS modules are based on ublox, so I guess they all should work as the same for voxl flight, right?
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For example, if I would buy a set of F9P rover + base station from Holybro:
https://shop.holybro.com/h-rtk-f9p_p1226.html?Could I simply replace and plug-in it on m500 without any other configuration? Or what updates I should do to enable F9P RTK on m500?
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Hi @Eric-Katzfey , please any thoughts on this question. Thanks.
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@yu-zhang If PX4 supports the modules in question then our flight core should also support them. I would try to figure out how other people have enabled RTK on PX4 and see if you can recreate what they did.
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@yu-zhang We did some experiments with RTK back in 2019 with one of these boards https://www.sparkfun.com/products/15136 and one of these Pixhawk units https://docs.px4.io/v1.9.0/en/flight_controller/pixhawk_mini.html.
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@Eric-Katzfey Thanks so much for double-checking! The used RTK is F9P (u-blox F9) based, so I think the Holybro one should also work for PX4 unit.
I will double-check with the team in Holybro if everything is good for the replacement then.
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Hi @Eric-Katzfey and @yu-zhang. I'm trying to use the same module you're talking about in this chat (https://www.sparkfun.com/products/15136) with VOXL2, but I haven't been able to get it to work. I would like to know if it is compatible with VOXL2 and what would be the steps to make it work. Thanks!
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@xav04 We have not tried that GPS board with VOXL 2. The PX4 implementation on VOXL 2 is custom and many device drivers need modification to be able to run correctly. That is because the architecture is split between the applications processor (ARM multicore running Linux) and a DSP running an RTOS. Most device drivers run on the DSP and due the differences in the environment need customization. However, you could run the GPS driver on the applications processor instead. It's much more likely that you can use the standard PX4 GPS driver on the applications processor without customization. However, you would need to have access to a UART that is visible from the applications processor for IO. This add on board would provide that: https://www.modalai.com/collections/voxl-2-add-ons/products/usb-3-uart-expansion-adapter?variant=40740708876339. If you were to use that board, what would you be using for a compass (magnetometer)?
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@Eric-Katzfey Thanks for your reply! I'm not quite sure what compass I'm going to use, but if you know of any reliable module, I'd really appreciate it if you let me know. On the other hand, I may not be able to use that board since I'm using the 5G Modem Carrier Board which uses the same port (J3) as the VOXL 2 USB3.0 / UART Expansion Adapter. Is there any other way to connect this add on board or the gps?
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@xav04 I'll see if I can get any recommendations on compass, but usually these come integrated with the GPS. I think the best way to use the sparkfun GPS will be to try to get it going on the DSP. I'll take a look at it and see if there is an easy way to get it working.
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@Eric-Katzfey Thank you very much! I will be waiting for your message
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Hi @xav04, GPS board on VOXL 1 can work with sparkfun GPS via the standard PX4 GPS driver.
I went to Holybro F9P instead of the sparkfun, and it works fine with VOXL 1. For VOXL 2, as Eric said, you may have access to a UART to see if it works.
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Hi @yu-zhang, thank you for your reply! To give you more context, I'm using VOXL2 with the 5G Modem Carrier Board, so I'm not able to use the VOXL 2 USB3.0 / UART Expansion as @Eric-Katzfey suggested to access to that UART port. However, I found that the 5G Modem, in the J9 port has an i2c+Apps UART. Do you think I could use this port to connect the sparkfun via the standard PX4 GPS driver?
Also, do you know if the Holybro F9P comes with a PX4 compatible built-in compass?
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@xav04 According to their spec http://www.holybro.com/manual/Holybro_H-RTK_F9P_GNSS_Spec.pdf it does have an ist8310 magnetometer which is supported by VOXL 2.
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@xav04 Yes, the M0090 5G board does have a UART and I2C that you can use on J9.
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@Eric-Katzfey and @yu-zhang thank you very much! I'll get the module and test it.
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@xav04 I am trying to do the same thing as you, by using the J9 port on the 5G Modem to attach an RTK GPS.
Were you able to do so?
