Someone PM'd me a few months back about issues loading the OTA software with Arduino Mac and what version OSX I was using. Appeared they were using older Mac so it appeared that may have been the issue. They used a PC and got going.
Today I built another GPS and tried to load the OTA software and got a "A fatal error occurred: Failed to write to target RAM (result was 01070000)". Tried my older (10 year old) Mac with same result. Both Mac's load the software fine onto my original GPS (screen dead but still works).
Did a little digging and it seems Lilygo's new FTDI chip doesn't work with the Mac UART or something along those lines. There are two work arounds. Use a PC or, download and auto instal the driver. Once downloaded CH34xVCPDriver_signed.pkg it auto instals and you have to authorise it via System preference security. After that everything is in Chinese and you have two buttons to push. Push them both and the software loads perfectly. Note to make it work you have to select a different port in Arduino...you now have two USB ports,
#1 /dev/cu.usbmodemXXXXXXXX (the original)
#2/dev/cu.wchusbserialXXXXXXXX (the new port that appears and need to select that)
I can't seem to paste the actual download link here but the thread that the download link is on is github.com/Xinyuan-LilyGO/LilyGo-T-Call-SIM800/issues/139 About 1/3 down the comment from genotix provides the link CH9102_Mac_Driver.zip
Of course use at your own risk but no one has reported any issues.
I have just posted a new version of GPS Speedreader (2.0) with changes for dual ESP32 loggers. Most importantly, this version can calculate speed results based on averages between the two units, taking into account differences in error estimates to ignore one of the two units if it has significantly lower accuracy than the other unit. More details at boardsurfr.blogspot.com/2022/06/gps-speedreader-2.html , downloads and change log at ecwindfest.org/GPS/GPSSpeedreader.html
To get averages from 2 units for a session, simply select both files in the "Open" dialog, and answer "Yes" when Speedreader asks about calculating averages.
Select to expand quoteFlex2 said..
Someone PM'd me a few months back about issues loading the OTA software with Arduino Mac and what version OSX I was using. Appeared they were using older Mac so it appeared that may have been the issue. They used a PC and got going.
Today I built another GPS and tried to load the OTA software and got a "A fatal error occurred: Failed to write to target RAM (result was 01070000)". Tried my older (10 year old) Mac with same result. Both Mac's load the software fine onto my original GPS (screen dead but still works).
Did a little digging and it seems Lilygo's new FTDI chip doesn't work with the Mac UART or something along those lines. There are two work arounds. Use a PC or, download and auto instal the driver. Once downloaded CH34xVCPDriver_signed.pkg it auto instals and you have to authorise it via System preference security. After that everything is in Chinese and you have two buttons to push. Push them both and the software loads perfectly. Note to make it work you have to select a different port in Arduino...you now have two USB ports,
#1 /dev/cu.usbmodemXXXXXXXX (the original)
#2/dev/cu.wchusbserialXXXXXXXX (the new port that appears and need to select that)
I can't seem to paste the actual download link here but the thread that the download link is on is github.com/Xinyuan-LilyGO/LilyGo-T-Call-SIM800/issues/139 About 1/3 down the comment from genotix provides the link CH9102_Mac_Driver.zip
Of course use at your own risk but no one has reported any issues.
The drivers you mention will likely only work on newer OS X versions. I've tried multiple times to install the driver you mention (and various others) on OS X 10.14.6, without any success. No big deal, since installing the OTA software is a one-time thing that works fin on Windows 10. Any updates after that can be done over wifi. I even do the Arduino development on my Mac.
Select to expand quoteboardsurfr said..
I have just posted a new version of GPS Speedreader (2.0) with changes for dual ESP32 loggers. Most importantly, this version can calculate speed results based on averages between the two units, taking into account differences in error estimates to ignore one of the two units if it has significantly lower accuracy than the other unit. More details at boardsurfr.blogspot.com/2022/06/gps-speedreader-2.html , downloads and change log at ecwindfest.org/GPS/GPSSpeedreader.html
To get averages from 2 units for a session, simply select both files in the "Open" dialog, and answer "Yes" when Speedreader asks about calculating averages.
Anyone using the averaging should note that the averaging is designed for units that use the same time of GPS chip, and not for combining results from different GPS chip types (Locosys and u-blox). The error estimate numbers that Locosys units like the GW-60 give (SDOP) are calculated differently from the error estimates that the u-blox units give (sAcc), and show very different characteristics. Therefore, comparing SDOP and sAcc makes little sense.
Also note that the averaging is done on a point-by-point basis. This allows the elimination of short artifacts (spikes) if these have a higher error estimate (they often, but not always, do - check the example pictures in my blog post). This means that the "intelligent" average speed results can actually be higher than the results from individual units.
I've decided to build one. Looking at ordering the parts now (ali express seagull !). Thanks Jan for releasing the source code. It's one the speedsurfing community can own and grow 
What is the process to get individual ESP-GPS-Logger units approved for GPSTC use ?
Select to expand quotejn1 said..
What is the process to get individual ESP-GPS-Logger units approved for GPSTC use ?
email GPSteamchallengeto discuss. (Use the 'contact' form)
Select to expand quotejn1 said..
I've decided to build one. Looking at ordering the parts now (ali express seagull !). Thanks Jan for releasing the source code. It's one the speedsurfing community can own and grow
What is the process to get individual ESP-GPS-Logger units approved for GPSTC use ?
I'd suggest to build at least two. Having two units mounted on both sides of the boom makes it really easy to check speeds. There's no way I go back to armband-based loggers. You could use a single unit mounted on top of your helmet, of course, but then you'll always have to ask someone else what speed it shows 
.
Hi,
Great project, I would like to use this on my board and dinghy. Are you able to provide the arduino code please? Many thanks.
You can find the source code on github : github.com/RP6conrad/ESP-GPS-Logger
Manuals : docs.google.com/document/d/1j86kj3bNMID3sHCRT7QTYyrL7IHeQnGPec1LajsDfB4/edit?usp=sharing
docs.google.com/document/d/1XJD6BV1Xay4nXo0cDuo_IOtxC_f1LyG7DE7X6KGlAB0/edit?usp=sharing
I think Jan forgot to include the at the front of the links
i.e. should be github.com/RP6conrad/ESP-GPS-Logger
docs.google.com/document/d/1j86kj3bNMID3sHCRT7QTYyrL7IHeQnGPec1LajsDfB4/edit
docs.google.com/document/d/1XJD6BV1Xay4nXo0cDuo_IOtxC_f1LyG7DE7X6KGlAB0/edit
Jan, maybe you could edit the first post on the thread with links to the source code and manuals? Maybe even some of the other links on this thread with regards to 3d printed cases and things like that?
thanks Shannon
I tried to add the links to the start post of this topic, but it looks that edit is only possible on recent posts... Can a moderator confirm this ?
Greetings, Jan.
Since a pile of people appear to be starting to make these and using the boom mount print I upgraded the design to included all the lessons learnt. Seems still lessons to be learnt as I used abrasion resistant polycarb which doesn't bond well with dichloromethane. The main improvement in this design is adding spacers between the display and polycarb face to allow the epoxy to fill easily with no air bubbles. They double also as blocking the photo sensitive area. The trim and cover are on the outside of the polycarb. Those who made the original print can just add the trim and cover to remove the ghosting and tidy the units up a bit. The original print still works fine with my units still working well after nearly 150 sailing days. You can read more about the changes, get the designs, see more photos plus I posted the gcode for fast printing at www.printables.com/model/233931-improved-windsurfing-diy-gps-boom-mount
Designed a shoulder/helmet mount 3D print for Jan's GPS. Basic motivation was the forearm seems to be a better viewing position when fully powered and you don't dare sneak a peek at the boom display. Initially made the angle between display and battery much larger so would fit forearm better when realised about 30 deg would also allow a close fit to helmet and work fine on shoulder. Design allows plug and play for a wireless charge receiver with USB connection which eliminates a few solder connections. Also allows the charging mat (Tx) to be moved around to optimise charging efficiency (over comes Freezer's over heating issue). Fits 25mm velcro/elastic for mounting on arm or a few rubber bands holds it nicely on the helmet between the GoPro mounts I have already on the helmet. Taken on the water a few times now on shoulder and appears to be useable so posting it here. Link to design and more waffle on link below.
www.printables.com/model/234045-shoulder-or-helmet-mount-for-diy-gps
Hey everyone,
Nice too see that project here . Its really nice to find stuff like this.
Just finished building the second one. Still I had some issues with the software part but finally was able to solve it.
Sent a detailed software documentation that worked for me to Jan, so he can maybe add it (can't post links here since I am too new).
Since I am planning to use a GoPo Hero 8 housing for the first ones I designed some 3d printed inserts that align all parts nicely and keep them in place. Will upload them later to printables. If someone needs them just PM me (yeah still cant post a link).
For the future I will also try a completely printed housing without epoxy. Maybe some ABS which can be sealed with aceton.
Had some success with getting stuff watertight in the past already by using ABS and Aceton. Maybe also some printed seals?
I am already hyped to use those things next time I am on water.
G'day everyone. Over the last couple of days I have managed to make w of these gps units and they both where working.
Today though one of them seems to not have the battery connected. The battery is working and the current is making it onto the board out of the connector but doesn't seem to go further than that.
It switches on with the usb power source. I am just wondering if I can get around what ever is wrong by soldering the battery to the v bat connection and a ground?
thanks Shannon.
There seems to be a weak "battery connector fuse" on the board, that easily burns. But the bat connection on the solder points is still working then. So, try to connect the battery direct to the "VBAT" and a "GND" solder island, and everything should work again. On the picture, VBAT is on the left lower side. Success !
You guys are so tech smart . I just upgraded from my old flip phone 
I reckon you would also understand all the buttons and features in a new car , including the info screen . They need to hold workshop classes for people like me when buying a new car .
Making a GPS, really ? , you guys should be working for NASSA or Dr Evil making a death ray .
Thanks jan! I did the shouldering this arvo and success! Now I just need some wind for a proper test!
I had the same thing with one of my units, and Jan's suggestion fixed it. The batter on this unit seems to deplete faster, but that may be the battery, or perhaps it just turned on while being jostled around on the drive home and the push button on the GoPro8 housing got a random "press". Otherwise, it's working great, like the 3 others (and more in the making ).
Select to expand quoteImax1 said..
You guys are so tech smart . I just upgraded from my old flip phone
I reckon you would also understand all the buttons and features in a new car , including the info screen . They need to hold workshop classes for people like me when buying a new car .
Making a GPS, really ? , you guys should be working for NASSA or Dr Evil making a death ray .
You don't need to be tech smart, you just need a friend who is.
building my GPS units was one of my most satisfying experiences of the year, because it was a challenge, but I did need some coaching.
Don't try to do it with Windows 7
Select to expand quoteWindxtasy said..Imax1 said..
You guys are so tech smart . I just upgraded from my old flip phone
I reckon you would also understand all the buttons and features in a new car , including the info screen . They need to hold workshop classes for people like me when buying a new car .
Making a GPS, really ? , you guys should be working for NASSA or Dr Evil making a death ray .
You don't need to be tech smart, you just need a friend who is.
building my GPS units was one of my most satisfying experiences of the year, because it was a challenge, but I did need some coaching.
Don't try to do it with Windows 7
If your keen Imax1 I can help you build one!
A little warning about the GPS chips: there may be some out there that are marketed as "BN220" with rather poor performance. I have ordered a batch of 6 from a supplier on Aliexpress based on price, which perhaps was a mistake. These are not "Beitian BN220" chips (which are "the original rip-off chips"), but are labeled just BN220. So far, I have not been able to get them to pick up more than 13-14 satellites, while other BN220 chips used in direct comparison went up to 28 satellites. The reported speed accuracy and observed errors while stationary (frequent peaks up to 5 knots!) are also quite poor. Looking at the reported satellites, it seems the chips do well receiving Galileo sats, but have problems with GPS and GLONASS, picking just a few of these.
This is not yet a final assessment, since I need to give the chips some time with a perfectly clear view of the sky, although my hope that this will help is low.
So if you order to build your own, I suggest to ask around which exact supplier has provided good chips (>24 sats used, sAcc around 0.3 or lower), and not just pick the lowest priced rip-off of a rip-off.
So if they have Beitian BN-220 they are the right ones? Mine cost around $20 from sky rc hobbies. Mine seems to be a knock off for sure. It seems to get about 18 satellites.
The BN220 I got from Aliexpress are definitely bad. I tested them driving and then on the water today, so they had a total of 2+ hours to get all the satellite fixes they could. The new BN220s never got more than 13-14 satellites, while an older one (from a different seller) got about twice as many. Here's a section from the driving test:
Speed on top, error estimates at the bottom. Blue is the old (good) unit, red and green are the new (bad) units. Pretty much garbage and unusable. I'll file a refund request with Aliexpress, but I'm afraid that's $80 (for 6 units) down the drain. I've tested only 3 so far, but they all show the same characteristics.
Select to expand quoteshannon19 said..
So if they have Beitian BN-220 they are the right ones? Mine cost around $20 from sky rc hobbies. Mine seems to be a knock off for sure. It seems to get about 18 satellites.
All BN220s are knock-offs in a sense. The genuine u-blox chips (NEO-M8) they imitate sold for at least twice the price. It turns out that the Beitian BN series actually is better than the genuine u-blox chips at dealing with high data rates. But this particular manufacturer/seller probably cut corners in the design to save a few cents, and the units do not have enough resources to track more than 14 satellites. I also saw a "tx buffer overflow" error in u-center when using the chips, which is not something I had noticed before.
If you get 18 satellites with just 2 GNSS systems enabled (which is probably still the default), you should be fine. However, you definitely should enable 3 GNSS systems, which should bump the number of satellites tracked into the mid-20s, and gives more accurate data, as shown earlier in this thread. In the config.txt is a parameter added : "gnss":3 (you'll also need to add a comma to the end of the line before the one you add).
The unusableBN220 chips I got were from the "TZT Official Store", also labelled as "ShengYang", on Aliexpress. The same page sells BN180, BN220, and BN880. I don't want to post a link to avoid chances someone buys from there. The ones I ordered before that worked were labelled "Beitian BN220". The last seller I used was Geekstory on Amazon. Prices are about 1/3 higher ($36 for 2) but the chips work.
All GPS-chips (ca 12) I have ordered on Ali do have the Beitian logo. All chips are OK, with 2 GNSS I receive 18 sats, with 3 GNSS 24 sats. But not al chips have the latest firmware, which is necessary for 3 GNSS. My Favorit is the BN220, as it has a faster fix then the BN180. Fix between BN220 / BN280 is comparable. Prices did vary between 10? to max 15? (when the Euro was still 1.2$...).
Select to expand quoteboardsurfr said..
The BN220 I got from Aliexpress are definitely bad. I tested them driving and then on the water today, so they had a total of 2+ hours to get all the satellite fixes they could. The new BN220s never got more than 13-14 satellites, while an older one (from a different seller) got about twice as many. Here's a section from the driving test:
Speed on top, error estimates at the bottom. Blue is the old (good) unit, red and green are the new (bad) units. Pretty much garbage and unusable. I'll file a refund request with Aliexpress, but I'm afraid that's $80 (for 6 units) down the drain. I've tested only 3 so far, but they all show the same characteristics.
Hi Boardsurfr,
Did you try interchanging known good BN220 unit with a bad unit, then repeating the test a few times ?, and then comparing the data ?
Does the fault follow the BS220 unit ?, or does it follow the enclosure ?
J
