Hello,
Anyone used a Logic Level Converter to make a Pro Micro 3.3v to send MIDI notes to a Keyboard?
https://www.sparkfun.com/products/8745
I can not make it to work, please HELP!
Many thanks!
Can you tell us what you did, perhaps a schematic or drawing of what you wired up ? Perhaps furnish some details of the keyboard used ?
Hey Mee_n_Mac,
Reply appreciated! will post the digram momentarily. For now, please note I have another Arduino pro mini 5v connected directly to the ‘same’ keyboard and it works flawlessly.
Diagram attached below:
It appears you’ve got it connected properly to send data from the micro. Obviously there’s no data to be sent to the micro. I’d check to make sure the boost converter is working, measure the “high” voltage with a DVM and see if it’s correct. The only other thing I can think of is to ask why do you have the extra resistors (220 ohm ?) in line ? Be aware that the logic level converter will provide a hard ground on the high voltage side Tx line. I don’t know if the resistance might affect that, such that a logic low might not be detected at the keyboard. Also be aware the LLC doesn’t provide a hard logic high. It’s HV side output in a high state is a 10K connection to the high voltage source, a somewhat weak pull-up. I don’t know what the logic in the keyboard needs.
Hey Mee_n_Mac,
Advise highly appreciated! The resistors are there because that is what I have used with my Arduino Pro mini 5V, that is the only reason I have, I’ll check with the voltage as what you have said. I did tried to remove the 220 resistor of the TX pin going out to the midi keyboard but with no success. I’ll post the readings once I get home thanks again!!!
The last thing I can say is you could check that the LLC is working by commanding constant 0’s and 1’s via the Micro and measuring the HV side with a DVM. Verify it outputs low/gnd and “high” volts when it’s supposed to be.
Got it! Thank you!
LLC HV Side is verified
High is High
Low is Low
HV side is 4.97v DC
I will try to compare it with my working Arduino Pro 5v and find out if there is any difference in voltage output.
reginr:
I will try to compare it with my working Arduino Pro 5v and find out if there is any difference in voltage output.
Meh, S/B working at the measured voltage. Did it work with your Pro 5V ? If so check the blatantly obvious, like a wire now not connected or something like that. Assume nothing, verify ground connections, etc.
Noted. Will do!
Sorry I can't add any more useful. So far as I can see, you've got it all right. If it's not working, when it used to w/o the LLC, then something obvious, something you assume is good ... isn't. I've lost track of the number of times I've been bitten by a connection that I assumed was there (was even measured to be there) that ended up not being there later in time for some silly reason.reginr:
Noted. Will do!
Just a quick query, is a 3.3v 8Mhz Arduino able to communicate at a baudrate of 31250kbs ?..
Update:
Arduino Pro Mini 5v 16Mhz
Logic High - 4.94v
Logic Low - 2.1mv
Arduino Pro Micro 3.3v 8Mhz
Login High - 4.81v
Logic Low - 31.8mv
S/B working with those voltages.
While I can’t say from experience, if a 16 MHz Arduino can handle 115k bps, an 8 MHz Arduino should handle 31k bps. Are you getting garbage characters received (as best as you can tell) or no characters at all ? If this all worked with your 5V Arduino (and still does), perhaps you should connect the HV Tx out to the Rx of your 5V Arduino and use it as a “sniffer” to verify what you think is being sent by the 3.3V Pro.
Mee_n_Mac,
Thanks always for the inputs.
For now I decided to use my old Arduino Decimilia 5v
hook it up with an old Serial BT
Hook up my current pro micro 3.3v with another serial BT and just transmit the Midi Signal Wirelessly
I’l re-bump this thread when I have the time and equipment! Thanks again for everything! 