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> Hi all, > Before I go trying to fix this myself, thought I'd ask if anyone > knows the answer. The question is on the timing of writing > to the EEPROM (persistent variables) on the BX-24. I have > an application which is data-logging for 200 samples, 20 per > second. There is not enough ram for this so I am storing in > EEPROM every 50ms. I am getting the samples using timer1 > and the hardware interrupt capture pin 12 (not using the > InputCapture command). > > About 5% of the time, the eeprom write disrupts my polling > loop on the input capture flag which has to be checked at > least once every 2ms. So what happens is I get a bogus > result if I miss a transition due to the eeprom write. > > The documentation is not clear on when the parts of > the eeprom write cycle take place. Is there any way > to force this? I don't think I would have any problems if > I could write to eeprom immediately (takes ~5ms), then > start polling again with 45ms before the next write, > but that doesn't seem to happen automatically every > time. > > Thanks for the help, > Mark Skala

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Are you sure it's the EEPROM write that is causing the disruption? When I tried using the InputCapture pin to do my own capture of a 32 bit pulse train of about 65ms total duration, I found that each capture went blooey about 2/3 of the way through. I think the OS was up to something in the background. I switched to the Interrupt pin and can now capture the bits with no problem. On 11 Oct 2001, at 9:54, Skala, Mark A (Mark) wrote: > > Hi all, > > Before I go trying to fix this myself, thought I'd ask if anyone > > knows the answer. The question is on the timing of writing > > to the EEPROM (persistent variables) on the BX-24. I have > > an application which is data-logging for 200 samples, 20 per > > second. There is not enough ram for this so I am storing in > > EEPROM every 50ms. I am getting the samples using timer1 > > and the hardware interrupt capture pin 12 (not using the > > InputCapture command). > > > > About 5% of the time, the eeprom write disrupts my polling > > loop on the input capture flag which has to be checked at > > least once every 2ms. So what happens is I get a bogus > > result if I miss a transition due to the eeprom write. > > > > The documentation is not clear on when the parts of > > the eeprom write cycle take place. Is there any way > > to force this? I don't think I would have any problems if > > I could write to eeprom immediately (takes ~5ms), then > > start polling again with 45ms before the next write, > > but that doesn't seem to happen automatically every > > time. > > > > Thanks for the help, > > Mark Skala > > > > > > > > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> Get your FREE VeriSign guide to security > solutions for your web site: encrypting transactions, securing > intranets, and more! > http://us.click.yahoo.com/UnN2wB/m5_CAA/yigFAA/CFFolB/TM > ---------------------------------------------------------------------~ > - > > --- http://www.laser.com/dhouston/

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Dave, I can't measure time accurately on another pin, pin 12 is the one connected to the Atmel chip and its timer/ capture flag register. I know it's the eeprom because if I use the same code without the write, it is okay all the time. Thanks, Mark Skala ----- Original Message ----- From: "Dave Houston" <> To: <> Sent: Thursday, October 11, 2001 10:25 AM Subject: Re: [BasicX] EEPROM timing > Are you sure it's the EEPROM write that is causing the disruption? > > When I tried using the InputCapture pin to do my own capture of a 32 > bit pulse train of about 65ms total duration, I found that each > capture went blooey about 2/3 of the way through. > > I think the OS was up to something in the background. I switched to > the Interrupt pin and can now capture the bits with no problem. > > On 11 Oct 2001, at 9:54, Skala, Mark A (Mark) wrote: > > > > Hi all, > > > Before I go trying to fix this myself, thought I'd ask if anyone > > > knows the answer. The question is on the timing of writing > > > to the EEPROM (persistent variables) on the BX-24. I have > > > an application which is data-logging for 200 samples, 20 per > > > second. There is not enough ram for this so I am storing in > > > EEPROM every 50ms. I am getting the samples using timer1 > > > and the hardware interrupt capture pin 12 (not using the > > > InputCapture command). > > > > > > About 5% of the time, the eeprom write disrupts my polling > > > loop on the input capture flag which has to be checked at > > > least once every 2ms. So what happens is I get a bogus > > > result if I miss a transition due to the eeprom write. > > > > > > The documentation is not clear on when the parts of > > > the eeprom write cycle take place. Is there any way > > > to force this? I don't think I would have any problems if > > > I could write to eeprom immediately (takes ~5ms), then > > > start polling again with 45ms before the next write, > > > but that doesn't seem to happen automatically every > > > time. > > > > > > Thanks for the help, > > > Mark Skala > > > > > > > > > > > > > > > > ------------------------ Yahoo! Groups Sponsor > > ---------------------~--> Get your FREE VeriSign guide to security > > solutions for your web site: encrypting transactions, securing > > intranets, and more! > > http://us.click.yahoo.com/UnN2wB/m5_CAA/yigFAA/CFFolB/TM > > ---------------------------------------------------------------------~ > > -> > > > > > > > > > > > > > > --- > http://www.laser.com/dhouston/

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