Press "Enter" to skip to content

nuxx.net Posts

P3 v1.5 MIDI Sync Issue

Looking inside of Ivan's P3 while the micro grabbers are connected to ground, sync in (to the PIC on GP4), and what should be MIDI out (from the PIC on GP0).

So, in wrapping up the testing of Ivan’s P3 I found one more problem: MIDI Sync output isn’t working. I think I’ve narrowed the issue down to the software running on the PIC which handles this. Here’s what I know as of last night:

· U1, the main CPU on the P3, has two lines coming out of it which either connect directly to the DIN sync port or to U19 used for conversion to MIDI sync.
· I am seeing nice square waves on the PIC’s GP4, and these pulses change width with tempo change.
· The line running from U1 to the PIC’s GP5 goes high when the sequencer is running, then low when it isn’t.
· I don’t see any data coming out of the PIC on GP0, which is what connects through a 220Ω resistor eventually through to the MIDI port.
· There are no shorts on any of the lines.

In troubleshooting the PIC itself I have:
· Read out the firmware from the PIC, and received new firmware from Colin (the designer) for the PIC. These did not match, and the new firmware did not resolve the issue.
· Tried a spare PIC which I had sitting around in my parts pile.
· Wrote a test program to blink all GPIO lines on and off and successfully ran it on both PICs.
· Confirmed that the PIC is connected to power and ground and other lines, as expected.

After this, I pretty much have run out of ideas. This morning I threw the firmware Colin had sent me into a disassembler, and while I’m not very good at reading assembly, I think I’m that GP0 and GP1 are used as inputs and GP2, GP4, and GP5 are outputs, confirming that the firmware I was sent is for the v1.6 PCB. There is lots of BTFSS GPIO,0 and BTFSC GPIO,1 which are used for reading pins, and lots of BCF and BSF on GPIO,2, GPIO,4, and GPIO,5. GP2 (GPIO,2) seems to be used the most in the program, so I think it’s the MIDI port, and this would match what I see in my old photos of the v1.6 board, as GP2 connects through a 220Ω resistor to the pin header. GP4 and GP5 probably mirror the input received on GP0 and GP1, but I’m having difficulties confirming which pins are sync and which are enable.

I just pulled apart the older file which I had read out of the PIC previously and it seems to read from GP4 and GP5, with MIDI data going out of GP0. These port uses match my observations of the pinning of the v1.5 board, so I think that the older firmware looks somewhat right. That said, it clearly wasn’t working, otherwise I wouldn’t be posting this.

I think tonight I’ll try to write the originally-read firmware back into one of my new PICs, then I’ll drop it back in the P3, just to see what happens.

Oh, and for what it’s worth, this is my understanding of what the PIC12F629 on the P3, U19, does (or is supposed to do) on the the v1.5 boards: It watches for when GP5 goes high (an indication that the sequencer is running) and when it does, it sends out a MIDI clock message with each pulse it sees on GP4 (not sure if this is done at the rising or falling edge). It then stops sending these clock messages when GP5 goes low. On the v1.6 boards it seems to do something similar, but since it has three outputs I believe it also sends the DIN sync output as well.

There are also more photos of last night’s work at the bottom of this page in the last two rows.

UPDATE: One thing I didn’t test was input on the pins and the internal oscillator. I make a quick change to the blinky LED program to run from the internal oscillator and another version which I can use to test if all the inputs work. I’ll try that tonight. At this point it’s almost not enough for me to fix the problem, I want to know what wasn’t right.

Leave a Comment

Colin Fraser Saves The Day

R20 replaced with a 10K part, per Colin Fraser's suggestion, in an attempt to alleviate the issues with the LCD.

When I woke this morning I had received a response from Colin Fraser in regards to the problem mentioned in this post. He mentioned two things: the issue isn’t likely to be caused by timing because he specifically checks for the LCD to be available before writing to it, and that he has seen an issue where the transistor which enables the R/W line of the LCD doesn’t have enough gain. To increase this gain he suggested replacing the 22K resistor at R20 with a 10K part.

I did so as can be seen above and this is the result: a P3 displaying things properly. Thanks, Colin!

Now I just have to do a little bit more testing (I’m paranoid about these things), then I can pack up the P3 and send it back to Ivan. Of course, that will come after dinner. Danielle is in the kitchen with where they are making making naan and Mattar Paneer with this recipe from Manjula’s Kitchen. I’m looking forward to a very tasty dinner.

Leave a Comment

Odd LCD Problems in Ivan’s P3

For some reason, when booting the P3, it drops the first two letters of the 'Firmware check..' message. I'm not sure if this is the P3 mainboard booting faster than the LCD, or what.

Upon arriving home from work today I found a white box in the mail from Scotland indicating that the new LCD for Ivan’s P3 had arrived. This is the replacement that Colin (the Sequentix guy) offered to people as a replacement for PLEDs which had failed. After eating a bit of dinner I set to installing it.

Because of the spacing of the LCD and function switch board I had to file away a bit of the PCB in order to make it fit nicely. Thankfully Sequentix’s page on the replacement LCDs had mentioned this, so I was expecting to do it.

All in all, it went well. After getting the LCD working I installed the v4 firmware and MemX board, getting the machine wholly up to date.

I’m running into a bit of weirdness with the LCD, though. As can be seen on this page of photos, the display seems to be cutting off some characters during boot, corrupting others, and occasionally causing weirdness. I’ve tried making a new cable and replacing the IC directly connected to the LCD, but that hasn’t been successful. I’m really afraid that the controller on the LCD may be messed up. Hopefully tomorrow I’ll be able to use one of Ivan’s spare LCDs which he was sent (by way of me) by Crystalfontz as replacements for his failed PLEDs.

UPDATE: I just emailed Colin, the Sequentix guy, and asked for suggestions. After talking with a few people I’m starting to feel certain that the problem may simply be that the LCD doesn’t start up fast enough for the P3. It seems that with the HD44780 protocol the LCD talks the user can set up custom characters in the CGRAM (character generator RAM). While I may be way off base, I’m thinking that the P3 sets up the special characters it needs on boot, then tries to display stuff. I think that if the LCD isn’t running stable yet then these characters, along with data written to the display controller itself, could become corrupt or lost, displaying the symptoms like what I’m seeing. Hopefully I’ll find out for sure soon. If this is the problem then a fix would simply require the P3 to wait for another 250ms (or so) at power-on.

Leave a Comment

HP/EDS and Fog

Fog seen looking out my front window / doorwall on the morning of 13-May-2008.

When I was leaving for work this morning, and throughout almost the entire drive, it was abnormally foggy. This was really nice, as I like fog, I just wish I could have gone out in the woods on my bike and enjoyed it that way.

Also, it’s been confirmed that HP is going to buy EDS. I don’t know many details, except that EDS will probably maintain its name / brand, and that the drastic (~25% or so) increase in EDS’ share price made my 401(k) go up a bit, which is kinda nice.

Leave a Comment

The stuff one finds in the woods…

An old Civil Defense vehicle found amongst a bunch of trailers and mobile homes at the end of a road, right near the aforementioned tree farm.

One sure can find odd things back in the woods.

I’ve recently returned from visiting my grandparents up north and doing a bunch of biking along the roads and trails, finding all sorts of interesting places which I’d like to explore more in the future.

I ended up having to put the knobby tires back on my bike for the offroad riding, but I was glad I did. I had no problems wandering around all sorts of fire trails, dirt roads, and other random, interesting areas. One of those more interesting areas was what I first thought to be an oil drilling dumping ground. It contained all sorts of interesting metal parts, old vehicles, trailers (including some marked radioactive), and other discarded stuff. After talking to my grandparents it turns out that I was on the property of a friend of theirs named Charlie who happens to collect a bunch of stuff like that. Best I can tell, he is also the owner of the old CD vehicle seen above. (If any of you can figure out the city it is from based on this photo I’d love to know.)

While I didn’t go that far (only about 30 miles over the two days), I do definitely want to head back up there and do some more riding. I would definitely like to tackle the portion of the North Country Trail which I happened to come across, but I’m not really sure if it can be legally biked. The information I come across on this seems very, very mixed. I figure if I’m careful, stick to the trail, and don’t bother anyone it won’t be a problem. That said, I turned back at this point because it was too steep for me to ride up. There is, of course, a whole bunch of ORV trails in the area, but they are too sandy to ride on a bike. Even my wide knobby tires regularly sank in past the rim.

If you’d like to see the KMZ aggregated to cover most of this weekend’s riding it can be found here, with the nodes differentiating things by ride and date: 10-11-May-2008.kmz

The rest of the photos, including the ones from when I headed out wandering on the sandbar off of Old Mission Point, can be found here: Up North (May 2008)

(Oh, and yes, I know those photos are a bit crap. They were taken with my old Nikon Coolpix 5400 which was nice for its time, but is now just so-so. Also, it’s big and not weatherproof one bit. I’m thinking I’ll probably replace it with one of these Olympus shockproof and waterproof, internally zooming cameras. The quality probably won’t be great on them either, but at least it’ll fit nicely in my bag and I won’t have to worry about rain or a fall damaging it. Although, realizing that the camera is five years old, maybe those photos aren’t that bad…)

Leave a Comment

Traverse City Is Dull Unless You Like Shopping

I’m sitting in Espresso Bay in downtown Traverse City, leeching bandwdith from the first AP I found called ‘linksys’, tunneling everything via SOCKS (SSH tunnel). I drove up here yesterday in order to visit my grandparents who live about half-way between here and Grayling.

While I like visiting them, I find it a bit difficult to be in this area at times. I’d really, really like some nice veggie food, or at least some mostly-veggie Thai or Indian or Middle Eastern, but that doesn’t seem to be available. Despite being near water, seafood around here isn’t any fresher than it would be in Flint or Grand Rapids. There does seem to be a local organic / veggie eatery called the Homegrown Organic Eatery (WARNING! MySpace link), but it closed at 8pm. I think I’ll probably just end up grabbing a bean burrito from Taco Bell on the way back to my Grandparents’ place.

On the upside, I did get to do a bunch of outdoor things today. I first went for a bike ride, then swapped the touring tires out for knobbies, then went another 10 miles or so back on random trails that I came across in the woods. Some of the trails were particularly difficult because if the extremely (in many cases 100%) sandy soil in this area, but overall it was fun. I also managed to end up on some piece of property full of oil drilling remains, semi trailers (one marked Radioactive), campers, mobile homes, and other pieces of scrap. I think my grandpa knows the owner of the property and hopefully I’ll be able to get back there tomorrow with my camera and grab some photos.

My main reason for heading to Traverse City today was so that I could make my way up to Old Mission Point (at the 45th Parallel) and wander around the beach there. I ended up wandering down the beach, walking across a bunch of rocks, and ending up way out in the water on a rather interesting sand bar after quite a bit of walking. I think it’d be nice to bike up the peninsula one day, but it’s 18 miles (each way) of rather steep hills. The main road up to the point does have nice bike lanes on it, though. There are also some quite nice trails along the point in the park which might be good for riding around as well.

In lieu of other food I think I’ll just head back to my grandparents house now and grab a bean burrito from Taco Bell on the way. My grandma made turkey for dinner, but that’s one meat I particularly don’t like. No matter what it always tastes dirty to me.

Oh, something very positive: lunch today was pizza from the small convenience store near my grandparents house. While picking up the pizza with my grandpa I found that the store carries a small assortment of very good beers along with the normal stuffs. There were probably two doors worth of better Michigan beers and other imported things. While I don’t plan on getting any beer this weekend, it’s nice to know that it’s available in the future.

5 Comments

La Jalisciense Corn Tortillas

A fresh corn tortilla from La Jalisciense in Detroit cooking on the stove with some shredded cheese on it. What a wonderful dinner / snack.

On Monday Danielle was in Detroit while her mom was having some stuff done at the hospital, so she swung by Mexicantown and picked up some La Jalisciense flour and corn tortillas.

One of these corn tortillas toasted on the stove, with a bit of cheese, makes for an absolutely wonderful late dinner / evening snack. I can’t stop eating them. Now to go make more, except this next one will be flour, I think…

Leave a Comment

Flat New Holland Beer: The Poet

Yesterday while Danielle was over I picked up a six pack of New Holland’s beer The Poet. I’m happy because Meijer is now carrying it, which makes it easy to pick up for enjoying with dinner. Unfortunately, all but one or two bottles of this beer seem to be as flat as you can see up above. There’s just no head / foam on it at all.

After finding the contact page on New Holland’s site I emailed Isaac Hartman, who is listed as the Ambassador of Great Beer (Sales). Hopefully he’ll respond and, at the very least, do what he can to ensure that their beer at Meijer is better in the future.

As this beer tastes pretty sweet, I’m figuring that it didn’t bottle condition right. Maybe New Holland gave Meijer a few cases of them expecting them to age a bit in the store room or on the shelf and instead they just went into refrigeration. Or… who knows. It’s definitely not right, though.

Leave a Comment

Roland TR-606 for Jan

Detail of the area around the tempo knob on the TR-606 showing that it's worn down to the paint.

Today after getting home from work I ate some carrots and hummus and hopped on my bike, intending just to run up to the bank and go to the ATM. Instead I ended up going to the ATM, then winding my way through industrial parks up to 24 Mile and M-53, where I turned around under the bridge after coming across this amusingly broken set of toy guns. I then wound my way home, taking time to ride through every industrial road / park I came across, racking up a total of 15 miles.

Yesterday I received this box in the mail, and tonight I opened it and grabbed some pictures. See, a guy by the name of Jan Czmok, who is the only person (that I know of) besides me to build a complete MIDIbox SID-NUXX (you can see his photos of his here) wanted to buy a for-repair TR-606 on eBay, but the seller would only ship to the US, so I’m relaying it for him. Here is a mirror of the auction, if you’d like to see it. For reference, the auction closed for $255.

I wish him luck in fixing it up because it’s not in particularly good shape. While it doesn’t seem to have a smell, the damage to it makes me think that it was either left in a garage for a few years, that it survived a flood, or maybe that it was just left at the bottom of a septic tank full of angry lobsters.

If you would like to see the full photos of the TR-606, click on this link.

2 Comments