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Electronics/Modules and components purchases

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generic MIDI 2 USB interface

December 2018: I bought a generic MIDI2USB interface from Lisa Li store whose motto is "Providing great products with lower price".


TL;DR: it does not work. Don't buy!

First of all, the interface was not recognized when plugged in and it didn't even light its "ON" LED. Left with a non-working piece of electronics junk, I decided to open the case which, fortunately, wasn't sealed or glued.

At first look, it seems a better interface than many others in that it looks like there is an optocoupler (U2) to prevent frying the equipment hooked to the interface. Also, the main chip (U1) is not hidden under a blob of expoxy. However both chips have no markings whatsoever and the main chip, which is often a 20 pin CH345, is a 14 pin chip. So go figure what it is!


The bad news

  • chips have no markings.
  • the PCB ground pin (GND) had a cold joint. I removed the blob of solder, cleaned the pad with solder wick and then soldered the ground pin properly. At last the interface would light up when plugged in and be recognized as a "USB2.0-MIDI" device with "USB\VID_1A86&PID_752D&REV_?110&MI_00" id's and manufacturer "(Generic USB Audio)". That looked promising, did it not ?
  • I hooked up the interface to a Yamaha MIDI and computer, fired up CakeWalk and... some keys played on the Yamaha keyboard would not register in CakeWalk, even when played at snail pace. For reasons best known to the device, it was always the same notes that didn't register in CakeWalk. Buffer problem ? Hum... less promising!
  • How about playing a one-track song (no chords, slow beat arpeggio) loaded in CakeWalk ? Same behavior: not all notes would play back to the Yamaha keyboard.
  • I contacted the Lisa Li store and they first offered to refund 1 buck for fixing the cold joint. Thank you but... no thank you. I was then offered a full refund less cost of shipping (about 50% of the item price though it was "Free shipping" when ordered... ). Thank you but... no thank you. I was then offered a discount on future orders. A discount on items that don't work ? Thank you but... no thank you. After another 3 or 4 emails, I got a full refund. And a piece of electronics junk that traveled thousands of kms.


The good news

  • None for the product itself.
  • the half-good news is you can eventually get a refund but be prepared for lengthy (in time) back and forth messages.


Conclusion

My advice : don't buy it! I suggested Lisa Li store to remove that item from their store but it is still there.

The failure may be due to an inadequate opto-coupler (too slow) but with no markings on U2 it's difficult to check and/or find a replacement.


GG-1802 "M8N" GPS

In Jan 2019 I bought a GG-1802 GPS from TOPGNSS Store on AliExpress.

The product page' title refers to the M8N (a µBlox module). Knowing the newest M8N firmwares are now over 526 KBytes, I asked the seller the size of the Flash memory on their GG-1802 GPS and whether it could be upgraded to latest firmware. The answer came back: 4MB and, yes, I can upgrade to Galileo.

Fine, 4MB is over µBlox minimal recommendation of 2MBytes (2 MBytes = 16 Mbits) for upgrade and data-logging.


The bad news

  • Based on the seller's answer, I ordered the GG-1802 but, guess what, it cannot be upgraded because it has 512 KBytes of Flash memory only!
    • Being rather tempted to believe µBlox u-center, and, at this point, I trust µBlox more than the TOPGNSS seller, the identifier of the Flash memory is VID:0x00c8-PID:0x4013 which is a GigaDevice GD25Q40 chip. No wonder, that's a 512 KBytes chip that costs 0.40€ per unit at Digi-Key.
    • To match µBlox minimum requirements, a 2 MBytes GD25Q16 chip which costs an horrendous 0.46€ per unit at Digi- Key would have fit nicely.
    • A mere 0.06€ difference! And that's buying the chips in quantity of 1, bulk is a lot cheaper (-25% and more)! And there are no hidden costs when using the proper chip: both chips have the exact same pinout and size. No change to the PCB, no change to the manufacturing line nor process, no nothing. It's just a question of loading the pick and place machine with a different SMD reel.
    • Manufacturing a product with such an obvious planned obsolescence for a gain of less than 0.06€ is just beyond my understanding. Either the manufacturers have tons of GD25Q40 chips on hands and get rid of them or it's a willful decision. In both cases they manufacture a subpar product they don't have to be proud of.
  • The next thing is that it is not a µBlox M8N module so the title on the product page is wrong too.
    • To be fair, the GG-1802 MAY be manufactured around a genuine µBlox MT8030-KT chip and it gets recognized as an M8N by µBlox software. However I didn't open the casing to prove me right or wrong on this account.
  • To be fair this one is not promised on the product page: although the µBlox MT8030-KT chip has UART, SPI and DDC/I²C interfaces, only UART is available on the GG-1802.
  • After purchase, communication with the seller is mostly a one way street.


The good news

  • It is tiny, light weight and runs on as low voltage as 3,3V so it can be powered by a LiPo cell.
  • it can be configured to receive up to 3 out of the 4 main constellations (Beidou, Galileo, GLONASS, GPS).
  • µBlox u-center (free software) sees the GG-1802 as an M8N and we can configure the GPS with said software.
  • The GG-1802 has the v3.01 firmware in ROM so it is "Galileo ready" however by default it receives signals from GPS and GLONASS. You need to configure it with µBlox u-center if you wish to include the Galileo constellation. As of end 2018, some 22 Galileo satellites have been launched.
  • The GG-1802 does have some Flash memory so the configuration can be saved.
  • It seems very sensible. Even indoor, 4 meters away from the nearest window, surrounded by buildings, it easily catches signals from 8+ satellites. Note that I live at the top floor of a 4 story concrete building and in these circumstances the deviation may easily reach a 50/75 meters radius (signal bouncing off surrounding buildings ?) and when conditions get worse (rain, wind) I occasionally get a 400/500 meters wandering. Obviously your mileage may vary.
  • At less than 6€ it's cheap.


Conclusion

The seller blatantly lied about the Flash memory size, yet I didn't raise a dispute because the GPS works. It does not do everything it promised to but for the most part it works. However I don't like being lied to. Who does ?

Should you buy it? Now that you know the bad points and considering the good points too, it's really up to you. Most other vendors will sell you the same or even worse (no Flash memory at all) supposedly M8N GPS. At least, this seller has better prices than its competitors and it ships fast.

Would I buy it again? If I accept the non-upgradable issue then definitely yes.

To the manufacturer: put the proper Flash size chip (an increase of 0,06€ at the end of the production line) and raise the selling price by 0,20€.



Bike alarm with remote-control

In 2017 I got one of those vibration triggered bike alarms that fit on the seat tube and that is activated by a remote control.

It looks like this:

It fits nicely on the seat tube, just make sure it is low enough so the battery can't be easily removed. By the way the wireless label should be visible (mounted upside) and the battery lid on the down side! At least it prevents the battery to be removed by a would-be thief and it keeps the water from entering the alarm.

The alarm is based on a 433MHz H3V4F receiver, a vibration/ball sensor, an unknown chip (PIC? NE555?) and a piezo buzzer. The remote control is based on a TL2260S chip (actual marking is TL2260SD-4) and a LR1 SAW resonator (433.92MHz).



The bad news

  • the 9V battery gets drained in a matter of days even when the alarm is switched off therefore the running cost is high.
  • mine is VERY sensible and the alarm may go off when a truck passes close to the parked bike. I've seen other people mentioning their alarm is not sensible enough. Go figure what you'll get...
  • the claimed 110 Db must be at 3cm. Still, it's loud enough to draw somone's attention, should anyone care...


The good news

  • The remote control makes it easy to switch the alarm on and off from a distance.
  • at 4/5€ it's cheap but don't be fooled: the components inside the remote and the alarm are dead cheap.


Conclusion

Would I buy it again? Definitely no because the alarm is draining its 9V battery too fast making it an expensive alarm in the long run.

To the manufacturer: make sure the receiver doesn't draw so much current when the alarm is off. With the current design, the alarm is worthless.




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