pressure sensor and pic microchip

**jmurba** · 19th June 2006, 21:12

Hi all,

as anybody tried to implément the uwatec pressure sensor on a pic 16fXXX ?
before starting reading the data sheets ...if someone had done it (((-:

regards

jean mi

rdmmdr · 19th June 2006, 22:23

Uwatec Did Use Msi Sensors, I Don't Know If They Still Do. The Msi Sensor Is A Mv Output At A Max Of About 100 Mv . Using The Spare Channel Of Your O2 Sensor Opamp You Can Integrate It To Your Pic, Using An Analog Input. The Msi Sensor Is Good For Three Time Over Range Without Damage So The 100 Psi Sensor In The 85 Series Is Probably What You Are Looking For.
Rick

steevke · 20th June 2006, 06:54

There is a C DOS programsample on the intersema website that shows a bitbanged example. Just port it.

Steven

***jradomski*** · 20th June 2006, 08:21

Quote: (Originally Posted by steevke)

There is a C DOS programsample on the intersema website that shows a bitbanged example. Just port it.

Steven

The intersema sensor is probably the best available for ease of use (its an absolute pressure sensor so no calibration is necessary), but there are drawbacks.. The mounting system sucks.. Expect several revisions until you get a syste, that doesnt leak usually, but you'll still run into problems..

Every VR3 I have seen that has flooded it was obviously the pressure sensor, KJ has had his share of tbles as well.. Most work perfectly (after severaly mounting revisions), but he still gets the occasional surprise..

The leaks can be anythig from a full flood to just a bit of moistuire getting in..

They seriously need to redesign the xducer case..

The VTI sensor looks like its going to be the one to use but it has been delayed until early next year..

**jmurba** · 21st June 2006, 22:35

Hello Joe,

I managed to get a couple of samples (my best friend asked it from alctelaleniaspacefrance , 2 days agos he recieved 10 units).
I did not know for the leaks I'll pay attention.
before spending hours in the datasheets i was looking for someone that had worked on a pic implementation...to acelerate.
I know the component sends a 14 bit word under a 3 wire serial communication protocole but I don't know which standard, syncrone , asyncrone, usart, usart.....????

regards

jean mi

Quote: (Originally Posted by jradomski)

The intersema sensor is probably the best available for ease of use (its an absolute pressure sensor so no calibration is necessary), but there are drawbacks.. The mounting system sucks.. Expect several revisions until you get a syste, that doesnt leak usually, but you'll still run into problems..

Every VR3 I have seen that has flooded it was obviously the pressure sensor, KJ has had his share of tbles as well.. Most work perfectly (after severaly mounting revisions), but he still gets the occasional surprise..

The leaks can be anythig from a full flood to just a bit of moistuire getting in..

They seriously need to redesign the xducer case..

The VTI sensor looks like its going to be the one to use but it has been delayed until early next year..

***jradomski*** · 22nd June 2006, 05:56

Quote: (Originally Posted by jmurba)

Hello Joe,

I managed to get a couple of samples (my best friend asked it from alctelaleniaspacefrance , 2 days agos he recieved 10 units).
I did not know for the leaks I'll pay attention.
before spending hours in the datasheets i was looking for someone that had worked on a pic implementation...to acelerate.
I know the component sends a 14 bit word under a 3 wire serial communication protocole but I don't know which standard, syncrone , asyncrone, usart, usart.....????

regards

jean mi

Its a bit banged protocol.. There is no chip select, so a specific start sequence is required prior to each communication.. from a programming standpoint it is somehwere between programming I2c and SPI..

data is clocked in relation to a user controlled clock pulse..

They have a APP note on the website that gives detailed sourcecode in C on how to communicate (by a pc parallel port) with the sensor and can easilly be ported to other applications.

You really need to use a high level language like c, some of calculations required are not easy to implement in asm..

paulraymaekers · 22nd June 2006, 11:37

hello, what happens with the output at depth >130m ????
regards
paul

***jradomski*** · 22nd June 2006, 11:47

Quote: (Originally Posted by paulraymaekers)

hello, what happens with the output at depth >130m ????
regards
paul

The depth is actually calculated deeper than this and it maxes out somehwere around 300m, if I remember correctly (it varies from sensor to sensor (calibration coeffcients) and by temperature due to adjustment of the reading)..

the overpressure rating of the sensor is about 3X the rating.. The sensor's AD converter is optimized for a specific region, beyond this reading the error of the sensor increases dramatically.. There are no guarantees on the accuracy beyond 14bar absolute, the farther you leave this reason the larger error you should expect..

rdmmdr · 22nd June 2006, 17:21

Quote:

The depth is actually calculated deeper than this and it maxes out somehwere around 300m, if I remember correctly (it varies from sensor to sensor (calibration coeffcients) and by temperature due to adjustment of the reading)..

the overpressure rating of the sensor is about 3X the rating.. The sensor's AD converter is optimized for a specific region, beyond this reading the error of the sensor increases dramatically.. There are no guarantees on the accuracy beyond 14bar absolute, the farther you leave this reason the larger error you should expect..

as long as the sensor is not damaged by the over pressure, all is does is throw off the linearity if the opamps for the a/d converter do not max out. and most time all it takes is adding somemore calibration points to get to unit accuracy back. if you start to see hysterisis problems then you have damaged the cell from over pressure. once you leave the rated zone the linerarity is what is effected.

rick

***jradomski*** · 22nd June 2006, 18:05

Quote: (Originally Posted by rdmmdr)

as long as the sensor is not damaged by the over pressure, all is does is throw off the linearity if the opamps for the a/d converter do not max out. and most time all it takes is adding somemore calibration points to get to unit accuracy back. if you start to see hysterisis problems then you have damaged the cell from over pressure. once you leave the rated zone the linerarity is what is effected.

rick

agreed.. Performance is not guaranteed above the rating.. the sensor can be expected to work reasonally well to about 20bar absolute (its not as linear but it can be used with software adjustments), beyond this has shown the sensors vary on how they handle the over pressure, which always surprises me since the VR3 claims its a 300m computer (I havent checked the latest specs but that is what was claimed last time I looked) and it only uses a 14bar sensor..

My current "test" sensor is good to about 23bar (checked against a digital pressure transducer), the last one I had only did 21 well ( I ruined it at 25bar - sensor lost accuracy and stability)

19th June 2006, 21:12	#1 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 920	pressure sensor and pic microchip Hi all, as anybody tried to implément the uwatec pressure sensor on a pic 16fXXX ? before starting reading the data sheets ...if someone had done it (((-: regards jean mi
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19th June 2006, 22:23	#2 (permalink)
rdmmdr designer of death Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Mar 2006 Location: kerman,california Posts: 372	Re: pressure sensor and pic microchip Uwatec Did Use Msi Sensors, I Don't Know If They Still Do. The Msi Sensor Is A Mv Output At A Max Of About 100 Mv . Using The Spare Channel Of Your O2 Sensor Opamp You Can Integrate It To Your Pic, Using An Analog Input. The Msi Sensor Is Good For Three Time Over Range Without Damage So The 100 Psi Sensor In The 85 Series Is Probably What You Are Looking For. Rick
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20th June 2006, 06:54	#3 (permalink)
steevke Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Sport Kiss Join Date: Jul 2005 Location: Belgium Posts: 317	Re: pressure sensor and pic microchip There is a C DOS programsample on the intersema website that shows a bitbanged example. Just port it. Steven
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20th June 2006, 08:21	#4 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: pressure sensor and pic microchip Quote: (Originally Posted by steevke) There is a C DOS programsample on the intersema website that shows a bitbanged example. Just port it. Steven The intersema sensor is probably the best available for ease of use (its an absolute pressure sensor so no calibration is necessary), but there are drawbacks.. The mounting system sucks.. Expect several revisions until you get a syste, that doesnt leak usually, but you'll still run into problems.. Every VR3 I have seen that has flooded it was obviously the pressure sensor, KJ has had his share of tbles as well.. Most work perfectly (after severaly mounting revisions), but he still gets the occasional surprise.. The leaks can be anythig from a full flood to just a bit of moistuire getting in.. They seriously need to redesign the xducer case.. The VTI sensor looks like its going to be the one to use but it has been delayed until early next year.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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21st June 2006, 22:35	#5 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 920	Re: pressure sensor and pic microchip Hello Joe, I managed to get a couple of samples (my best friend asked it from alctelaleniaspacefrance , 2 days agos he recieved 10 units). I did not know for the leaks I'll pay attention. before spending hours in the datasheets i was looking for someone that had worked on a pic implementation...to acelerate. I know the component sends a 14 bit word under a 3 wire serial communication protocole but I don't know which standard, syncrone , asyncrone, usart, usart.....???? regards jean mi Quote: (Originally Posted by jradomski) The intersema sensor is probably the best available for ease of use (its an absolute pressure sensor so no calibration is necessary), but there are drawbacks.. The mounting system sucks.. Expect several revisions until you get a syste, that doesnt leak usually, but you'll still run into problems.. Every VR3 I have seen that has flooded it was obviously the pressure sensor, KJ has had his share of tbles as well.. Most work perfectly (after severaly mounting revisions), but he still gets the occasional surprise.. The leaks can be anythig from a full flood to just a bit of moistuire getting in.. They seriously need to redesign the xducer case.. The VTI sensor looks like its going to be the one to use but it has been delayed until early next year..
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22nd June 2006, 05:56	#6 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: pressure sensor and pic microchip Quote: (Originally Posted by jmurba) Hello Joe, I managed to get a couple of samples (my best friend asked it from alctelaleniaspacefrance , 2 days agos he recieved 10 units). I did not know for the leaks I'll pay attention. before spending hours in the datasheets i was looking for someone that had worked on a pic implementation...to acelerate. I know the component sends a 14 bit word under a 3 wire serial communication protocole but I don't know which standard, syncrone , asyncrone, usart, usart.....???? regards jean mi Its a bit banged protocol.. There is no chip select, so a specific start sequence is required prior to each communication.. from a programming standpoint it is somehwere between programming I2c and SPI.. data is clocked in relation to a user controlled clock pulse.. They have a APP note on the website that gives detailed sourcecode in C on how to communicate (by a pc parallel port) with the sensor and can easilly be ported to other applications. You really need to use a high level language like c, some of calculations required are not easy to implement in asm.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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22nd June 2006, 11:37	#7 (permalink)
paulraymaekers rEvo's daddy Current Rebreather/s: rEvo Other CCR Home Build Other Rebreather/s: rEvo Other CCR Home Build Join Date: May 2005 Location: belgium Posts: 1,638	Re: pressure sensor and pic microchip hello, what happens with the output at depth >130m ???? regards paul __________________ www.rEvo-rebreathers.com .... the earth is flat, Elvis is alive, and radial scrubbers give longer dwell time than axials...
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22nd June 2006, 11:47	#8 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: pressure sensor and pic microchip Quote: (Originally Posted by paulraymaekers) hello, what happens with the output at depth >130m ???? regards paul The depth is actually calculated deeper than this and it maxes out somehwere around 300m, if I remember correctly (it varies from sensor to sensor (calibration coeffcients) and by temperature due to adjustment of the reading).. the overpressure rating of the sensor is about 3X the rating.. The sensor's AD converter is optimized for a specific region, beyond this reading the error of the sensor increases dramatically.. There are no guarantees on the accuracy beyond 14bar absolute, the farther you leave this reason the larger error you should expect.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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22nd June 2006, 17:21	#9 (permalink)
rdmmdr designer of death Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Mar 2006 Location: kerman,california Posts: 372	Re: pressure sensor and pic microchip Quote: The depth is actually calculated deeper than this and it maxes out somehwere around 300m, if I remember correctly (it varies from sensor to sensor (calibration coeffcients) and by temperature due to adjustment of the reading).. the overpressure rating of the sensor is about 3X the rating.. The sensor's AD converter is optimized for a specific region, beyond this reading the error of the sensor increases dramatically.. There are no guarantees on the accuracy beyond 14bar absolute, the farther you leave this reason the larger error you should expect.. as long as the sensor is not damaged by the over pressure, all is does is throw off the linearity if the opamps for the a/d converter do not max out. and most time all it takes is adding somemore calibration points to get to unit accuracy back. if you start to see hysterisis problems then you have damaged the cell from over pressure. once you leave the rated zone the linerarity is what is effected. rick
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22nd June 2006, 18:05	#10 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: pressure sensor and pic microchip Quote: (Originally Posted by rdmmdr) as long as the sensor is not damaged by the over pressure, all is does is throw off the linearity if the opamps for the a/d converter do not max out. and most time all it takes is adding somemore calibration points to get to unit accuracy back. if you start to see hysterisis problems then you have damaged the cell from over pressure. once you leave the rated zone the linerarity is what is effected. rick agreed.. Performance is not guaranteed above the rating.. the sensor can be expected to work reasonally well to about 20bar absolute (its not as linear but it can be used with software adjustments), beyond this has shown the sensors vary on how they handle the over pressure, which always surprises me since the VR3 claims its a 300m computer (I havent checked the latest specs but that is what was claimed last time I looked) and it only uses a 14bar sensor.. My current "test" sensor is good to about 23bar (checked against a digital pressure transducer), the last one I had only did 21 well ( I ruined it at 25bar - sensor lost accuracy and stability) __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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