A tale of two 9's

[vigilante397]

Another demo video showing off some of the handling here:  https://youtu.be/hHlw6phnWmI

Well that was pretty freaking great. Really excellent job, looks amazing!

[bean]

Another demo video showing off some of the handling here:  https://youtu.be/hHlw6phnWmI

Well that was pretty freaking great. Really excellent job, looks amazing!

Yeah, I mean...holy hell!

[pruttelherrie]

Thanks guys!

Stuff can be found here: https://github.com/pruttelherrie/Ehx9-All/

[pruttelherrie]

Sooooo.... I started to do a complete walkthrough of the modification, starting with an unmodified pedal, making pictures and notes etc. but I'm all out of headers... 

So now it's waiting for Tayda. Will keep you posted.

[pruttelherrie]

Hehehe so there were a few instabilities in the software, caused by me cheaping out and leeching the 3.3V power from the mainboard. Especially the TFT backlight takes quite a bit and this week I put more SPI flash chips on the flashmultiplexerboard so the screen would freeze now and then.

Nothing a good ol' LM317 can't fix, so after adding a piece of perfboard with a 3.3V regulator dedicated for the TFT and the blackpill, all is fine again.

"Should have put that on the controller board from the start." - Yeah I know *sigh*

[Leetut]

Amazing work!
How did you copy the eeprom chip?

[pruttelherrie]

You can read them out like any other SPI EEPROM, using 'flashrom' and a suitable programmer.
You can either desolder the chip or read it out in-place, by keeping the DSP in reset by pulling pin 3 of the programming connector low (see multiplexer-pcb schematic in the github linked above). Keeping the DSP in reset prevents it from using the SPI bus so you can read the chip uninterrupted.

[Ben N]

But what if 9 turned out to be 6?
I'll let myself out.

[bean]

But what if 9 turned out to be 6?
I'll let myself out.

Everything sounds groovy in the Upside Down.

[Leetut]

You can read them out like any other SPI EEPROM, using 'flashrom' and a suitable programmer.

I used a CH341a usb programmer, saved mel9 data as 8mb bin file

[Leetut]

String 9 uses a MX25L12833F

[pruttelherrie]

String 9 uses a MX25L12833F

Good to know, same as the MEL9 it seems. How do they do the freeze function in the String9? Is it a momentary footswitch? Main PCB might differ from the others in that case. (true bypass? etc)

[Leetut]

it just the same 3pdt switch as the rest,
the freeze function either freezes your note until you play another, then it freezes the new note,
or it freezes until you turn the effect off,
led flashes when not froze,

[chouxglaze]

Followup.

Also, I decided that with a 74HC138 I can make a selector for the /CS signal.

[edit] (after reading free electron's post): Yep, that would work too! For two chips. The 9-family consists of 6 pedals at the moment, I was thinking of designing a PCB for that maximum of flash chips, addressable with a microcontroller.

If one wasn't worried about controlling the pedal with midi/a microcontroller, could this mod be done with a sp6t and some pull up resistors for the /cs signal and a "take" switch connected to the reset pin? I don't see myself adding midi to my board, and as nice as presets would probably be I'm mostly looking to mash my Mel9 and B9 together for space.

Sp6t only in case I expand in the future, don't see myself ever wanting the bass9 though.

[chouxglaze]

Interestingly, it seems my Mel9 has an MX25l6445E in it, unlike the 128 previously reported. I'm wondering if the actual contents of the chip are different or if they just used whatever suitably sized chips they had laying around. It's not a super modern revision either, judging by the lack of a dry mute switch. Still waiting on parts to arrive but I've opted to use the same demultiplexer chip pruttelherrie uses and a BCD rotary switch to choose a setting over just a straight sp6t to limit how many wires I need to run, and a reset button of course. We'll see if it works once i have the parts 😬.

[pruttelherrie]

could this mod be done with a sp6t and some pull up resistors for the /cs signal and a "take" switch connected to the reset pin?

Sure!

I've opted to use the same demultiplexer chip pruttelherrie uses and a BCD rotary switch to choose a setting over just a straight sp6t to limit how many wires I need to run, and a reset button of course.

Cool. Please keep us posted!

[chouxglaze]

It works! The PCB I ended up making has the footprints a little too small which made for some annoying soldering but otherwise things have mostly gone off without a hitch using the bcd knob and switch.

The only hiccup I ran into was finding out all the new pedals with the dry mute switch seem to have MX25L12833Fs instead of the MX25L6445Es I mostly ordered. The chip only seems to be using about 10% of its memory though, and I was able to truncate the file from the 128 to fit it onto the 64 and everything seems to be working despite that.

Gotta say that I really appreciate y'all doing the legwork in this thread, really wasn't too hard of a mod once I got my mind wrapped around what needed to be done! Excited to start playing with this thing at gigs again.

Not my best solder job by a longshot but here are the guts. https://i.postimg.cc/mDJqJW17/IMG-4771.jpg