Carvin V3 - perplexed

[nickb]

The 595s have +5v on Vcc. I see pulsating DC on the SCLK which goes away when the channel switches are toggled. LCLK however has nothing, or I see nothing on the scope at all.

I guess we're at a point where we're trying to narrow it down to the 595s or the Micro. Do my results help?

You need to measure the levels on SCLK, DATA and LRCK. LRCK is there I bet, but it is narrow and doesn't happen very often making it hard to see. Set up your scope in normal trigger mode so you can see SRCK, then just move the probe to LRCK and chances are you'll be set up right to see it- scope brightness up, room lighting down

[lowell]

The SCLK is about .8v p-p pulsating DC at about 10uS. I moved the probe over and there is nothing on LCLK. When I change the voltage to 10mv range on the scope I see what looks like noise... just a line of fuzz.

[Jazz P Bass]

LCLK (STCP on the datasheet) is the shift register clock.

74HC_HCT597 Pin out.pdf

I don't see anything, flip flop wise, really functioning without it.

74HC_HCT597.pdf



I would try replacing U6.

[nickb]

The SCLK is about .8v p-p pulsating DC at about 10uS. I moved the probe over and there is nothing on LCLK. When I change the voltage to 10mv range on the scope I see what looks like noise... just a line of fuzz.

I bet LRCK is there, You just can't see it on your scope.


Look at the Vih(mn) and Vil(max) specs in the data 597 or 595 sheet. A 0.8 V swing is too small so something is causing that. Pull the things attached to the those signals one at a time: the 595's are the micro outputs and the 597 is the inputs. Any one or more could be bad. If it's still wrong after pulling them, the micro is toast.

[lowell]

I just saved a lot of time haha. I realized my scope wasn't set to "calibrated" upon my measurement. SCLK is +/-2.5v or 5v p-p. So this being the case, do we think the micro is the issue?

[nickb]

I just saved a lot of time haha. I realized my scope wasn't set to "calibrated" upon my measurement. SCLK is +/-2.5v or 5v p-p. So this being the case, do we think the micro is the issue?

Duh! A 5V swing is good. Now look at signal levels on SHIFT DATA6 in i.e. U2 pin 14 and LCLK U2 pin 12.

[Jazz P Bass]

The micro (U1) would be the issue if it alone is loading down the signal.

I see that U4 is also tied to SCLK.

[lowell]

Ok so Carvin support finally got back to me. He is saying that even if I replace these ICs that it'll need to be SHIPPED to Carvin so that they can reprogram the new IC/s. ?? I asked if they could advise me on this as I've put many hours into it already, but he said

We have to program the eeprom after replacing those ICs and it can only be done here since we have the programmer.

I am posting this to see if anyone knows what exactly he is talking about. I've asked him twice via email, but he just says the same thing...that it needs to be shipped. I completely understand if he is correct and I'm not writing this as a statement of dissatisfaction, but simply curious for the sake of exercise if anyone is keen to this procedure or what equipment is needed.

[drewl]

EEPROM- electrically eraseable programmable read only memory.

The chips can't do anything until they are programmed to perform their function.
Car in has the software to put on the chips and I doubt they will release it.

[lowell]

Ok gotcha makes sense thanks for the input.

[nickb]

Ok so Carvin support finally got back to me. He is saying that even if I replace these ICs that it'll need to be SHIPPED to Carvin so that they can reprogram the new IC/s. ?? I asked if they could advise me on this as I've put many hours into it already, but he said

I am posting this to see if anyone knows what exactly he is talking about. I've asked him twice via email, but he just says the same thing...that it needs to be shipped. I completely understand if he is correct and I'm not writing this as a statement of dissatisfaction, but simply curious for the sake of exercise if anyone is keen to this procedure or what equipment is needed.

To program them you need both the programmer and the firmware than gets loaded into the processor OTP memory. So, having neither of those means you'd have to ship it to them.

Right now, you know there is something hairy with the data/ sclk/ lrck as (1) things aren't working properly and (2) when you load them with your scope probe the situation changes.

Go are verify the levels of the serial clock, the data and the load pulse i.e on the

input side you have:
Serial clock U1 pin 2 ( already checked above)
Serial data in U1
Load U1 pin 1

output side there is:
Serial clock U1 pin 2 ( already checked above)
Serial data out U1 pin 8
Load U1 pin 3

You cannot make any deductions unless you have reliable data (i.e measurements) to work from. Go get the data. If your scope cannot be made to display LRCK then the only option is to replace U2, U6 and U7 and cross your fingers.

[lowell]

Well at this point the customer has grown impatient, understandably so, so he's gonna grab it. I don't want to make him wait more so I can "see" if I can fix it.

Hey, next time this comes up I can cut my losses. Thanks for the help!