Breadboarded DINx1 sending all data only on D7 of 74hc165

[demym]

Hi, i have assembled a DINx1 on a breadboard.

But, i get some data in MIOS Studio (i've uploaded the MIDI128 onto the Core) only when i put pin D7 on 74hc165 to Low. The data i get is, in practice, all data (i see many many program changes on the MIOS Studio Midi Monitor... If i ground any of the other inputs of the 74hc165, i get absolutely no response.

I've followed the troubleshooting suggestions on the wiki, and i've triple checked for shorts on the breadboard or even on the Core (i resoldered something just to make sure).

But nothing has changed, my DINx1 responds (and with all of the data) when i ground pin D7...

Have no more ideas... was so thrilled to attach some encoders from an old broken V-Amp !!!

Someone can help ?

Thanks a lot, have a nice time

[TK.]

Hi,

pull the PIC and the 74HC165 out of the sockets, and use a multimeter beeper (or the ohmmeter function) to check following connections:

• PIC Pin RD3 -> 74HC165 Pin Clk
  
• PIC Pin RD2 -> 74HC165 Pin LD
  
• PIC Pin RD1 -> 74HC165 Pin QH
  

If these connections are ok, check for shorts between the pins, e.g. check that the multimeter is not beeping when checking RD3 against RD2, RD3 against RD1, RD2 against RD1

Thereafter check Vss/Vdd as well, and all permutations between Vss/Vdd and RD1/RD2/RD3

This should help to identify the short or unconnected cable.

Best Regards, Thorsten.

[demym]

Thanx

So, i'm not really practical with this kind of test (only measured V till now...)..

The meaning is: there should be some resistance beetween PIC pins and corresponding indicated 74HC pins ?

Anyway, i used the beeper function with the pin couples you suggested ,and it beeped for all three, apart from RD2 - RC (J9). Looking to the soldering, it was bad; i soldered, and made once beep test, getting the beep on that couple.

This was done with the PIC and the 74hc165 swapped out of their sockets.

Believing that the unsoldered pin was the culprit, i tried once DIN + Core.. But i still get all 128 midi messages, and only on D7 of the 74HC165...

What do you mean for 'permutations between Vss/Vdd and RD1/RD2/RD3' ?

Thanks, anyway

[TK.]

The resistance between directly connected pins shouldn't be higher than ca. 0.1 Ohm...

With permutations I mean all possible combinations between Vss (Ground track), Vdd (+5V track) and the RD1/RD2/RD3 pins.

See also http://en.wikipedia.org/wiki/Permutation

Means:

check Vss against RD1: no beep expected

check Vss against RD2: no beep expected

check Vss against RD3: no beep expected

check Vdd against RD1: no beep expected (but resistance should be 10k, caused by R9)

check Vdd against RD2: no beep expected

check Vdd against RD3: no beep expected

You could do the same at the 74HC165 site, but considered that Clk/LD/QH are directly connected to RD1/RD2/RD3, and there is no short between these pins, the results should be identical:

check Vss against QH: no beep expected

check Vss against LD: no beep expected

check Vss against Clk: no beep expected

check Vdd against QH: no beep expected (but resistance should be 10k, caused by R9 of the core module)

check Vdd against LD: no beep expected

check Vdd against Clk: no beep expected

Best Regards, Thorsten.

[demym]

Thanks Thorsten.

I'll try the permutations tonite. In the meanwhile, i forgot to say that i am using a 74LS165 instead of a 74HC165. I have already posted to the forum asking if it's equivalent to use the LS version of the 165, and the response was Yes.

Do you see any problem or issue related to the different version of the chip ?

I'll update you on the permutation test result.

Thx

[demym]

Update:

So i made the permutation tests between Vss, Vdd and RD1,2,3... Sadly enough, results are exactly as you predicted. And keeps not working as it should.

Really don't know where to look for anymore.

Thanks anyway for your support, think i'm going to switch on the J5DIN stuff (which i have already implemented and make it work, thanks to this excellent forum).

Sure, a DINx1 would open a great door..

Have a nice time

[sebiiksbcs]

I am having a quite similar problem. I use a breadboarded DINx3, and it sends all kinds of messages only when D7 of the first DIN is triggered.

Interestingly, after exchanging the breadboarded DINx3 with spare DINx4s from SmashTV I had around, the behaviour is the same. The problem doesn't seem to be on the DIN PCBs.

The point is: I used a fairly long wire from the core to the DINxX PCB. It is about 1,5 metres! How about you? So my problem seems to be the Core-DIN connection.

[sebiiksbcs]

As expected, it seems the wire has been too long. I cut it down to about 0.3 metres and it works fine. A minor problem was one cold soldering joint on the breadboard DINx3 (resulted in that pin's random DIN events from time to time because of bad grounding), but I think the main issue mentioned earlier was the too long wire.