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vwaudiguy
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« on: July 28, 2011, 06:01:01 PM »
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Any idea what would cause a Willem GQ-4X to suddenly stop being able to write? It's a 95040..It reads fine just won't write..I've checked all the connections and everything's fine. I've also tried both 95040 options in the device section.
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kls
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« Reply #1 on: July 28, 2011, 08:14:00 PM »
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Is this in circuit or has the device been desoldered?
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vwaudiguy
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« Reply #2 on: July 28, 2011, 08:25:41 PM »
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On the board. I was using the sonoma clip. I was successful ~ 10 times before with other ecu's of the same type. I took a very close look at the clip, and noticed a few of the pins were pushed inwards a little, so thinking I wasnt making proper connection, I decided to solder 8 thin wires directly to the board/95040 with the same result.. I've pulled them off before, but the glue is a bit of a pain. The only other thing I did since the last time it worked was upgrade the same laptop to windows 7..I thought of this possibility and installed the updated software (for the GQ-4X) on an XP machine with the same results.
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kls
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« Reply #3 on: July 28, 2011, 09:31:51 PM »
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I have never had an issue reading eeproms in circuit but on some boards (ME7.5 1.8t mainly) I have had issues writing in circuit with a UPA-USB programmer. It was always the write protect line, in the end I had to tie it high with a low value resistor. When UPA-USB has a problem it indicates the dataline thats being held low/hi etc - does the GQ-4X happen to do the same?
When we read/write in circuit the programmer is often "forcing" outputs from the ECU's microcontroller to a state they don't really want to be in. The programmer is also providing power to parts of the ECU which can be a problem, especially if the micrcontroller on the ECU tries to read/write to the eeprom while we are.
I would try tying the WP# pin of the eeprom high with a low value resistor (100 ohms or less) and see what happens. Or try reading/writing a chip that has been removed from the board to verify the programmer still works properly. Its not impossible for in circuit reading/writing to have damaged the programmer.
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vwaudiguy
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« Reply #4 on: July 29, 2011, 07:54:15 AM »
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Everytime the GQ-4X gave a "successful write" message even though the chip contents were unchanged. I was thinking last night that if the ecu sat around for a long time maybe there is less stray voltage stored in the caps/etc and this makes is harder to flash on-board? Most of the ones I did before were removed from the car minutes before the write process, and this last one that wouldnt write was from a recycler, so who knows how long it sat. I will try again today to flash off the circuit and see what happens. I didn't know you could damage the programmer if working on proms in circuit! I figured since they made adapters for this purpose it should be relatively safe. Thanks for your input KLS...I'll report back with what I find. I assume I can check a spec sheet for the location of the wp pin?
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infinkc
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« Reply #5 on: July 29, 2011, 08:50:39 AM »
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you have a different chip or another chip to try and write to? some reason the 95040 may have went bad, if you need another i have one.
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vwaudiguy
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« Reply #6 on: July 29, 2011, 08:52:48 AM »
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I sent you pm infinkc. Thanks!
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infinkc
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« Reply #7 on: July 29, 2011, 09:48:38 AM »
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for future reference here is a datasheet attached.
Write Protect (W)
This input signal is used to control whether the memory is write protected. When Write
Protect (W) is held low, writes to the memory are disabled, but other operations remain
enabled. Write Protect (W) must either be driven high or low, but must not be left floating.
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« Last Edit: July 29, 2011, 09:50:14 AM by infinkc »
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vwaudiguy
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« Reply #8 on: July 29, 2011, 10:09:01 AM »
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driven hi/low through a resistor, correct? Any special resistance?
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infinkc
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« Reply #9 on: July 29, 2011, 10:25:59 AM »
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driven hi/low through a resistor, correct? Any special resistance?
kls mentioned above to try a 100ohm or less, mostly for protection. you could just tie it high with vcc with a jumper if you wanted to. |
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vwaudiguy
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« Reply #10 on: July 29, 2011, 03:15:08 PM »
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Do I need it there during the whole write process or just a sec or two before?
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kls
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« Reply #11 on: July 29, 2011, 05:43:51 PM »
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The entire write process.
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vwaudiguy
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« Reply #12 on: July 29, 2011, 05:54:26 PM »
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So...I took the eeprom off the board and soldered wires directly to the chip and it worked. But..I also put back in my XP hardrive that I was able to do the writes with before with success...I don't really have time to try things, I just needed it back up and running. I'm leaning towards the problem is of it being in the circuit, but I was able to read/write plenty of times with it in the circuit with the soic adapter before..On a side note MCUmall had a great tech support guy who talked with me about the issues @ 6pm from his house (heard his baby crying in the backround haha)! Unbelievable in this day and age..He was very knowledgeable and was able to answer/verify anything I needed to know off the top of his head. The next time I need to do this I'll use the Win 7 laptop and report back..I have some chips on the way. Thanks for all your help fellas! I did not need to do anything with wp either, but it's still good to know it exists.
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kls
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« Reply #13 on: July 30, 2011, 01:26:37 AM »
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* SNIP*
I did not need to do anything with wp either, but it's still good to know it exists.
This is as it should be. The programmer will handle pulling the line high during a write. The problem comes from writing in circuit as there are other devices connected to the eeprom that may be trying to hold the line low and the programmer may have current limiting (safety) in place so it can't "force" the logic state required. When I read/write an eeprom in circuit my UPA-USB often gives a Vcc out of range error on the first try but generally works the second time as its charged up some of the ECU capacitors. either way, glad you got it working. |
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