hi!
i just “finished” my GM5 pcb, complete with eeprom (J1 J2 J3 disconnected (knife)).
i couldn’t wait to plug it in (just GM5 in USB of PC, no instrument yet)
result:
as soon as plugged in LED is on, but not very bright,
but neither report of pc like “new hardware found” nor LED brightness change when sending midi notes from MIOS keyboard…
is this normal? can i damage sth when i plug in a synth / sampler?
This is normal if you are using a blank EEPROM. It should contain the USB descriptors. Programming the EEPROM requires a core module + the mbhp_usb_gm5_eeprom application.
The EEPROM option is for experts only, and normaly not required.
The most simple way to ensure that GM5 is soldered correctly is to try out the default configuration (J1/2/3 connected to ground), so that the default descriptors are used.
Best Regards, Thorsten.
thank you, TK!
i must have done sth wrong because now i’ve fried my USB port ???
there can be a lot of reasons why that happened:
-first thing i soldered was the GM5 chip.
-i used a much too big soldering iron and tried to separate the pins by using a conventional (mechanical) desoldering pump.
-i probably had the wrong soldering station and was not earthed with wrist wrap.
-i had scratched off the jumper connections AND partially the jumpers, too, with a knife.
-after reading your answer i soldered a bridge connecting all 3 pins to an existing soldering point on ground.
-it could be that i did the last step with the optocoupler chip in the socket :o
but then i fried my USB, what means i don’t even have access to internet now (WLAN)! 
ok i knew about my skills & therefore i bought 3 boards and 5 chips, hoping at least 1 would last till it comes to building the GM5x5x5.
so i think i’ll build a new GM5 without making the mistakes and connect my internet via cable.
(+ buy a new USB port, any recommendations here?)
The most simple way to ensure that GM5 is soldered correctly is to try out the default configuration (J1/2/3 connected to ground), so that the default descriptors are used.
hm i thought default configuration would be for use with 5 IOs. but then i’ll try that!
EDIT: last behaviour: plugged in USB, LED didn’t light up but all windows related to USB/internet closed on the screen. nothing frozen just no USB anymore. …and maybe some smell (without smoke) from GM5 but i took off the plug immediately
now i finally have a working GM5 !!!
quite embarassing though: i got it almost for free from a very nice local midibox member who had already done the SMD part and i just had to finish the normal stuff! perhaps that’s why this one works?? not kinda DIY but working!
… but i definitely have to learn it soon too!
so many thanks to abcmann who was so kind & gave it to me!!!
& thanks TK!!!