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elRey
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« on: April 05, 2012, 08:00:42 AM »
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I know you ground the boot pin for ~5sec to put ECU into boot mode, then read/flash. I was wondering if you could leave the boot pin grounded the whole time. Once in boot mode, does it care whats on the boot pin?
For those that can't help but to ask why... I have a AMB that does not flash via OBD galletto. It has to be in boot mode. I have soldered a wire from boot pin to an unused pin on the connector. Then added that pin to the harness side, ran it to the OBD port (unused pin).
I can either use a momentary button on the galletto cable that grounds that pin. OR if ecu doesn't care if it stays grounds, I can just permanently ground the pin inside the galletto.
Thanks,
Rey
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littco
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« Reply #1 on: April 05, 2012, 08:53:42 AM »
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Wont work as the ecu needs to be in a NON BOOTMODE for it too run, so if it constantly in bootmode the car wont start. I assume that's what you mean, or are you saying can I boot it into bootmode and the flash while the pin is still grounded and then remove the grounded pin before I reboot and start the car.
Power to pin 3 remains even with ignition off, so the ecu might not enter bootmode I think.
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elRey
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« Reply #2 on: April 05, 2012, 09:09:30 AM »
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Wont work as the ecu needs to be in a NON BOOTMODE for it too run, so if it constantly in bootmode the car wont start. I assume that's what you mean, No, I'd remove the galletto cable before trying to start/run car or are you saying can I boot it into bootmode and the flash while the pin is still grounded and then remove the grounded pin before I reboot and start the car. ^This Power to pin 3 remains even with ignition off, so the ecu might not enter bootmode I think. I have successful flash an open ECU in boot mode while connect to car. Once I was in a pinch and didn't have my bench flash harness with me. So, I opened the ECU connected it to the car, grounded the boot pin while a friend turn ignition to on. This successfully put the ecu into boot mode and I flashed thru OBD connector. I could then just cycle the ignition and start the car. I've done this a few times. Can I flash with boot pin grounded? Thanks, Rey |
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« Last Edit: April 05, 2012, 09:14:00 AM by elRey »
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julex
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« Reply #3 on: April 05, 2012, 09:18:30 AM »
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Just try it lol.
Anyway, I believe that I flashed with it grounded all the time.
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littco
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« Reply #4 on: April 05, 2012, 09:25:37 AM »
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I did think a while back and asked the question on here, whether it would be possible to run 2 wires into the car, 1 on ground and the other the bootpin and have a switch to enable you to put the ecu into bootmode whilst in the car . In the end I just did short wires out of the vacuum port on the ecu cover with the switch but as of yet never needed to use it as the latest version of nef seems to work tickyboo on the ecu. Good to know I wont need to disconnect the battery after a bootmode flash as I had planning on doing if needed because of + power top pin 3
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nyet
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« Reply #5 on: April 05, 2012, 09:30:45 AM »
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No. That pin is shared by a data line on the flash (DQ4)
it is sampled on power up ONCE.
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« Last Edit: April 05, 2012, 09:37:52 AM by nyet »
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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elRey
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« Reply #6 on: April 05, 2012, 09:36:54 AM »
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No. That pin is shared by an address/data line (i forget which)
it is sampled on power up ONCE.
boot pin is shared? |
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nyet
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« Reply #7 on: April 05, 2012, 09:38:29 AM »
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yes, on ME7.1.1 it is pin24 on the 29F800, which is data pin 4.
if you ground it during programming, that databit will be stuck at 0.
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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nyet
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« Reply #8 on: April 05, 2012, 09:39:29 AM »
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Also, i wouldn't go wiring that pin around the cabin, for obvious reasons...
If you wanted to do it right, i'd use a simple FET circuit, and keep the FET VERY close to the data pin.
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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elRey
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« Reply #9 on: April 05, 2012, 09:45:57 AM »
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Sound advice, but I think you're too cautious.
To each his own.
I'll just try it,but be prepared to use a button. I have the button already in the galletto, but I underestimated my laziness.
Thanks,
Rey
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« Last Edit: April 05, 2012, 09:48:13 AM by elRey »
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nyet
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« Reply #10 on: April 05, 2012, 09:55:26 AM »
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Every wire that goes out from the ECU through the connector is carefully buffered and/or shielded against noise... a car is a VERY electrically noisy environment.
Call me cautious, but you really don't want noise on that pin. It is an active data bus DIRECTLY connected to the CPU carrying complex high speed signals, not a single pin that carries (generally) a DC signal (pullup/pulldown)
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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vwraceguy
Jr. Member
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« Reply #11 on: April 05, 2012, 10:31:51 AM »
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Agreed. the data bus lines are very easily faulted with electromagnetic interference (EMI). even bringing it out to a switch takes it farther from the ground plane. Every wire that goes out from the ECU through the connector is carefully buffered and/or shielded against noise... a car is a VERY electrically noisy environment.
Call me cautious, but you really don't want noise on that pin. It is an active data bus DIRECTLY connected to the CPU carrying complex high speed signals, not a single pin that carries (generally) a DC signal (pullup/pulldown)
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elRey
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« Reply #12 on: April 05, 2012, 11:55:08 AM »
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Thanks for the concerns. nothing ventured, nothing gained.
I'll post back if I have any issues. Looking at datasheet, as I understand it, I can keep the P0L.4 pin LOW while flashing.
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