3 ms·

I found the RP2040 to be great for HID projects like that because of its two cores and PIOs. So you don't have delays because of display/LED updates, and you c

by ta988 3y ago

I found the RP2040 to be great for HID projects like that because of its two cores and PIOs. So you don't have delays because of display/LED updates, and you can delegate some work to the state machines. If the author is around: I really enjoy your grease replacement idea and will definitely use that in my projects. Reminds me of the people removing the stops in step encoders. I was wondering a couple things about your approach: - do you have noise issues (as in a value oscillating by +/- 1 randomly) - do you see an issue in precision around your 0/max R positions? they are not exactly contiguous in the pot. - did you get a measurement of the angle equivalent for a change of 1 in your output value (equivalent of step angle in a step encoder)

gero_ 3y ago
I was also thinking about the RP2040 for cost reasons, they are so damn cheap. But I'll go ahead with the Teensy and the PCB first before I'll try something like that. > - do you have noise issues (as in a value oscillating by +/- 1 randomly) I've implemented a dead zone logic for this: You have to move the pot a little bit before it “picks up” the movement. I think I've tuned this quite on the safe side and it still feels instant. I'm working on a video demonstration that will hopefully show it. For testing, I was running some automation in Bitwig for an hour and did things like knocking on the table while it ran; if there was any CC message, it would take over the automation so after an hour I would have seen some green indicators to restore automation control. > - do you see an issue in precision around your 0/max R positions? they are not exactly contiguous in the pot. No, it feels very smooth. I had some issues with the logic for the points where the directions reversed, but after figuring that out, I can no longer tell where the 0/max positions are. > - did you get a measurement of the angle equivalent for a change of 1 in your output value (equivalent of step angle in a step encoder) No; it's analog and there's the deadzone logic so I don't think it is quite as simple as this, but since we're having 4096 values across 360 degrees it would be 0.09 degrees. I do believe that 12bit is actually a bit too much to be reasonable and it is probably more about the timing/bandwidth at this point, not resolution.
- ta988 3y ago
  Thanks. You are doing USBMIDI you can use higher rate than normal serial midi, and you can have up to 16 parallel midi ports. Depending on how the tinyusb stack is configured on Teensy it may require tweaking it a little.
- _Microft 3y ago
  You could put both a Raspberry Pi Pico footprint and Teensy footprint on your custom PCB and later decide which one to populate?
anymouse123456 3y ago
Just a PSA here. I'm a huge fan of the RP2040, and use it in a number of products. Please be aware of the problems with the ADC before assuming it will work for certain applications. https://www.hackster.io/news/raspberry-pi-confirms-it-is-investigating-a-flaw-in-the-raspberry-pi-pico-rp2040-adc-95c393b55dfb https://www.hackster.io/news/raspberry-pi-confirms-it-is-inv...

by ta988 3y ago

gero_ 3y ago

I was also thinking about the RP2040 for cost reasons, they are so damn cheap. But I'll go ahead with the Teensy and the PCB first before I'll try something like that. > - do you have noise issues (as in a value oscillating by +/- 1 randomly) I've implemented a dead zone logic for this: You have to move the pot a little bit before it “picks up” the movement. I think I've tuned this quite on the safe side and it still feels instant. I'm working on a video demonstration that will hopefully show it. For testing, I was running some automation in Bitwig for an hour and did things like knocking on the table while it ran; if there was any CC message, it would take over the automation so after an hour I would have seen some green indicators to restore automation control. > - do you see an issue in precision around your 0/max R positions? they are not exactly contiguous in the pot. No, it feels very smooth. I had some issues with the logic for the points where the directions reversed, but after figuring that out, I can no longer tell where the 0/max positions are. > - did you get a measurement of the angle equivalent for a change of 1 in your output value (equivalent of step angle in a step encoder) No; it's analog and there's the deadzone logic so I don't think it is quite as simple as this, but since we're having 4096 values across 360 degrees it would be 0.09 degrees. I do believe that 12bit is actually a bit too much to be reasonable and it is probably more about the timing/bandwidth at this point, not resolution.

ta988 3y ago
Thanks. You are doing USBMIDI you can use higher rate than normal serial midi, and you can have up to 16 parallel midi ports. Depending on how the tinyusb stack is configured on Teensy it may require tweaking it a little.
_Microft 3y ago
You could put both a Raspberry Pi Pico footprint and Teensy footprint on your custom PCB and later decide which one to populate?

anymouse123456 3y ago

Just a PSA here. I'm a huge fan of the RP2040, and use it in a number of products. Please be aware of the problems with the ADC before assuming it will work for certain applications. https://www.hackster.io/news/raspberry-pi-confirms-it-is-investigating-a-flaw-in-the-raspberry-pi-pico-rp2040-adc-95c393b55dfb https://www.hackster.io/news/raspberry-pi-confirms-it-is-inv...