Guest s130zx Posted March 22, 2007 Share Posted March 22, 2007 so while i have my laptop connected to my ecu it will work fine at idle, but when you give gas and the volts rise the program will freeze up on the computer. my question is does this happen to anyone else, if so how do i fix the problem?? i have a 3.0 board and a relay board using msns 2.25 beta any help is greatly apreacated thanks Quote Link to comment Share on other sites More sharing options...
naviathan Posted March 22, 2007 Share Posted March 22, 2007 The volts rise? How much before it locks? Sounds to me like your alt isn't regulating properly. Quote Link to comment Share on other sites More sharing options...
z-ya Posted March 22, 2007 Share Posted March 22, 2007 The alternator regulation is not important as the MS has an internal 5V regulator for the ECU and RS-232 interface chip. You may have a problem with the internal regulator. Check pin 3 of U5 (regulator), or pin 16 of U6 (max232). The voltage on these pins should be a constant 5V, no matter what the battery voltage is. How much does the battery voltage fluctuate? Where is the +12V supply to the MS coming from. It should be connected to the battery (not the alternator, or starter motor). The battery acts as a large capacitor, which filters out low frequency noise. This is why it is important to connect the MS (or relay board) to the battery (thorough a fuse of course). Quote Link to comment Share on other sites More sharing options...
naviathan Posted March 22, 2007 Share Posted March 22, 2007 The alternator regulation is not important as the MS has an internal 5V regulator for the ECU and RS-232 interface chip. You may have a problem with the internal regulator. Check pin 3 of U5 (regulator), or pin 16 of U6 (max232). The voltage on these pins should be a constant 5V, no matter what the battery voltage is. How much does the battery voltage fluctuate? Where is the +12V supply to the MS coming from. It should be connected to the battery (not the alternator, or starter motor). The battery acts as a large capacitor, which filters out low frequency noise. This is why it is important to connect the MS (or relay board) to the battery (thorough a fuse of course). Sorry, my thought was if the battery voltage is going up it could be causing the MS to restart from an overvoltage. Hence the voltage regulator would have to be bad. How can alternator regulation not be important? Measure voltage at your battery cold and measure again with the engine running. You'll have ~12v not running and ~14v running. The battery might filter noise, but a constant voltage increase is going to pass right on to the other components in the car. You can over volt the system if the alternator is throwing too much voltage out. Quote Link to comment Share on other sites More sharing options...
X64v Posted March 22, 2007 Share Posted March 22, 2007 How can alternator regulation not be important? Z-ya meant as far as the megasquirt board is concerned, it's not important. The little regulaters on the board can take 30+ volts without a problem, and still convert it to 5v. Quote Link to comment Share on other sites More sharing options...
HizAndHerz Posted March 22, 2007 Share Posted March 22, 2007 s130z, you don't say if the car keeps running. If so, MS is not locking up, just the commnucations with the PC. Are you using the computer's built-in serial port or a USB-to-serial adapter? USB adapters sometimes have a hard time keeping up with large amounts of data. You may need to change the communications parameters (writeBlocks and interWriteDelay). Take a look at the MS communications troubleshooting guide at http://www.megamanual.com/connect.htm. Quote Link to comment Share on other sites More sharing options...
z-ya Posted March 22, 2007 Share Posted March 22, 2007 Sorry, my thought was if the battery voltage is going up it could be causing the MS to restart from an overvoltage. Hence the voltage regulator would have to be bad. How can alternator regulation not be important? Measure voltage at your battery cold and measure again with the engine running. You'll have ~12v not running and ~14v running. The battery might filter noise, but a constant voltage increase is going to pass right on to the other components in the car. You can over volt the system if the alternator is throwing too much voltage out. The Alternator voltage will never cause the MS to reset (unless it goes below 5.5V, or over 30V). In that case, nothing will work. As long as the +5V logic regulator is working OK, the CPU will continue to process instructions. If the regulator is not functioning properly, it will most likely destroy the CPU and other components running off the +5V logic supply (VCC). I've got 20+ years experience in electronic design and debug, trust me on this one. Quote Link to comment Share on other sites More sharing options...
naviathan Posted March 22, 2007 Share Posted March 22, 2007 The Alternator voltage will never cause the MS to reset (unless it goes below 5.5V, or over 30V). In that case, nothing will work. As long as the +5V logic regulator is working OK, the CPU will continue to process instructions. If the regulator is not functioning properly, it will most likely destroy the CPU and other components running off the +5V logic supply (VCC). I've got 20+ years experience in electronic design and debug, trust me on this one. I didn't realize MS has such a variable amount it would regulate. Quote Link to comment Share on other sites More sharing options...
z-ya Posted March 22, 2007 Share Posted March 22, 2007 It is not so much the MS, but the voltage regulator used inside. It is a 500mV (0.5V) dropout regulator. This means, that it requires a minimum of 0.5V above the regulated output voltage to provide a stable output. Hear is the datasheet: http://www.national.com/ds/LM/LM2937.pdf Quote Link to comment Share on other sites More sharing options...
naviathan Posted March 22, 2007 Share Posted March 22, 2007 Cool, make a stupid statement and get some really good info in return. Thanks! Quote Link to comment Share on other sites More sharing options...
Guest s130zx Posted March 23, 2007 Share Posted March 23, 2007 sorry i was at the local track here in memphis the nhra sportsman class is in town this weekend and they were tunning tonight so any way my 12v source is the battery and yes the car stays running even after ms freezes up. also i have a usb from my ms not a serial port at all so no adapter i will check all the volts on my relay board tommorrow thank you for all the help Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted March 23, 2007 Share Posted March 23, 2007 Sounds like something's up with either the computer or the communications, not the MS box itself since the car still runs. Can you try it with a different computer? Also got any info on your setup? I've never heard of an MS box with no serial port. Mario Quote Link to comment Share on other sites More sharing options...
Guest s130zx Posted March 23, 2007 Share Posted March 23, 2007 i have used 3 dell computers and 2 other laptops it happens on all of them i had a friend build my ms box and he wired in a usb wire instead of a serial port Quote Link to comment Share on other sites More sharing options...
z-ya Posted March 23, 2007 Share Posted March 23, 2007 Go to Radio Shack and buy the correct cable. It should be a 9pin RS232 serial cable. USB is a twisted pair cable, and you may have the TX twisted with RX (not good). Pete Quote Link to comment Share on other sites More sharing options...
naviathan Posted March 23, 2007 Share Posted March 23, 2007 I cut this from the megasquirt forums. It might help as it seems several people have had success with fixing their comm problems this way: n limited testing, it seems that the parameter that has the most effect on this 'lost comms' issue for MS-II is 'interwrite delay'. The default value is 1, I have set it to 5 (in 'C:Program FilesMegaSquirtmtCommoncommon.ini') and have been unable to get the processor or comms to crash after a few hours (so far). Quote Link to comment Share on other sites More sharing options...
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