LIV4F-ME Firmware Documentation

[WiFiLuke]

Thanks for the info and the code snippets in this thread. However, they aren’t as good as proper documentation. Will the LIV4F docs get an update to include all of the LIV4FM / ME firmware details?

Related thread: https://community.st.com/t5/gnss-positioning/how-to-enable-rtcm-in-liv4f/td-p/701514/page/2

[GalaxyQuest]

Hi Luke,

Is there any specific information that you are looking for? If so, we can include in the software manual. I am guessing you already know that RTCM field descriptions are part of RTCM standard which is proprietary document. 

Please let us know if there is some specific information you would like.

Thanks,

George 

[adammk087]

You can enable RTCM in the EVB-LIV4F by configuring the receiver's settings through u-center software. Check the documentation for enabling raw measurement output and setting up RTCM messages.

[GalaxyQuest]

Hi,

It is best to use Teseo Suite to manipulate settings in Teseo Modules.  The reason I am saying that, there are features within Teseo Suite that are only compatible with Teseo Modules. Plus isn't Teseo Suite better graphically¯\_(ツ)_/¯ ? Not an unbiased statement here :) !

You would need to flash the module with dedicated binary to output raw measurements. You can find this at st.com

https://www.st.com/en/embedded-software/teseo-liv4fsw.html

[Tesla DeLorean]

I'd find it improbable that u-center (u-Blox) would allow for them to be enabled, might unpack / demux from the data stream.

The RTCM3 packets have a 0xD3 preamble, and the encapsulated data/packet can be validated without knowing the content. Which as pointed out, is a standard one can purchase from rtcm.org for a sizable wad of cash. Several copies on GitHub last time I went fishing..

The MSM messages are rather complex in their construction, being primarily a bit-stream. But still something which can be encoded/decoded by a Cortex-M3

https://github.com/cturvey/RandomNinjaChef/blob/main/RTCM3Test.c

https://github.com/cturvey/RandomNinjaChef/blob/main/RTCM3Wrapper.c

Tools like RTCM3-to-RINEX would be worth a look over, and tools from KernelSat

[WiFiLuke]

I've been able to load up the ME firmware and to apply a patch to the firmware to change which constellations are being used and reported on with MSM7 messages. The things that I can't find any documentation for are:

- RTCM messages

-- I can see what is being output, but the docs should explain what they are. The messages that can be fed into the PVT firmware are documented, why not the other way for the ME firmware?

-- Are there any optional RTCM message types that I can toggle? e.g. messages in the 1001-1068 range for reference station information, RTCM-SSR, and ephemerides.

- Base station configuration options

-- Survey in? 

-- Fixed location?

-- Antenna type and height

- Raw data

-- Are there any options for unprocessed raw data output like what can be generated by many other GNSS chips. e.g. RAWX, SBF.

[GalaxyQuest]

Hi,

I wanted to clarify regarding capabilities of LIV4F.

LIV4F can be configured in 3 ways,

- Standard PVT 

- DGNSS (MSM1) using SwiftNav Skylark - free to evaluate using Teseo Suite. You can configure Teseo Suite  or use STRSVR in RTKLIB to access Skylark server. Skylark server provides MSM1 data. LIV4F uses the supplied MSM1 data and computes precise position internally. Accuracy of few decimeters.

- ME - Sends out MSM7 messages for host MCU/MPU that runs RTK. LIV4F sends MSM7 messages to a host which will also receive MSM7 messages from a base station. It will be the host MCU that will calculate RTK precise position.

You had asked questions about base station. LIV4F operates only as a rover.

To access RAW data output, please refer to LIV3FL manual, for bit field definitions of PSTMPVRAW. (Will be adding to LIV4F s/w manual)

https://www.st.com/resource/en/user_manual/um2229-teseoliv3-gnss-module--software-manual-stmicroelectronics.pdf

You can enable PSTMPVRAW by

$PSTMSETPAR,1228,0x4000,1

$PSTMSAVEPAR

$PSTMSRR

Kalman Covariance message,

$PSTMSETPAR,1201,0x8000000,1

$PSTMSAVEPAR

$PSTMSRR

Hope this helps.