There was a known short between the serial data pins, and it was traced down to the junction board behind the screen. Macro lenses were added to the camera for a close-up shot. It was a small whisker of solder but enough to cause trouble.
A dental pick was used to scrape away the solder bridge. It was probably formed when the board was facing down, and the data wires were attached and reattached.
The old version of this project was used for generating notes, and it had two ports, so it was possible to monitor the MIDI notes with a commercial adapter while nearly simultaneously seeing them repeated by the Arduino. The two monitoring windows appear side-by-side in the picture below but the Arduino monitor, in white, inserts new data at the bottom while the MIDI monitor, in black, shows new data at the top
Data appeared in both windows at the same time, and it was clear the signals were from the same source. The Arduino program still did not show meaningful numbers, as evidenced by the above screenshot. Output was modified to display hexadecimal and bits. The old hardware's software was altered so it would output MIDI notes from 1 to 100, in order, then stop. A predictable pattern should be easier to spot. Hexadecimal was confusing, but when the individual bits were investigated, the first three bits (the note number) were counting up except the bits were all inverted!
At this point, the optocoupler had been removed from the system. I didn't understand the exact purpose was until I saw the inverted bits. The optocoupler served two purposes. The first purpose was to isolate the controller from potentially dangerous outside voltage and the second was to act as a NOT gate. A NOT gate is also known as an inverter. Clearly, the builder of decades worth of MIDI hardware knew better than I, and this was a nutritious reminder.
The rest of the posts for this project have been arranged by date.
First time here?
Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6
Disclaimer for http://24hourengineer.blogspot.com and 24HourEngineer.com
This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.
All information in this blog, or linked by this blog, is not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.
All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.
Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.
This blog, including pictures and text, is copyright to Brian McEvoy.
2019-04-15
Yesterday's short close-up
A dental pick was used to scrape away the solder bridge. It was probably formed when the board was facing down, and the data wires were attached and reattached.
Scraping away the solder short
The old version of this project was used for generating notes, and it had two ports, so it was possible to monitor the MIDI notes with a commercial adapter while nearly simultaneously seeing them repeated by the Arduino. The two monitoring windows appear side-by-side in the picture below but the Arduino monitor, in white, inserts new data at the bottom while the MIDI monitor, in black, shows new data at the top
Data seen by Arduino and data from MIDI to USB converter
Data appeared in both windows at the same time, and it was clear the signals were from the same source. The Arduino program still did not show meaningful numbers, as evidenced by the above screenshot. Output was modified to display hexadecimal and bits. The old hardware's software was altered so it would output MIDI notes from 1 to 100, in order, then stop. A predictable pattern should be easier to spot. Hexadecimal was confusing, but when the individual bits were investigated, the first three bits (the note number) were counting up except the bits were all inverted!
Inverted bits
At this point, the optocoupler had been removed from the system. I didn't understand the exact purpose was until I saw the inverted bits. The optocoupler served two purposes. The first purpose was to isolate the controller from potentially dangerous outside voltage and the second was to act as a NOT gate. A NOT gate is also known as an inverter. Clearly, the builder of decades worth of MIDI hardware knew better than I, and this was a nutritious reminder.
The rest of the posts for this project have been arranged by date.
First time here?
Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6
Disclaimer for http://24hourengineer.blogspot.com and 24HourEngineer.com
This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.
All information in this blog, or linked by this blog, is not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.
All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.
Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.
This blog, including pictures and text, is copyright to Brian McEvoy.
2019-04-15
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