Cold spray, where do you buy?
in [Design]
|
Prev: Mosquito killer
Next: Finally!
From: Frank Buss on 11 Apr 2010 15:48 langwadt(a)fonz.dk wrote: > I seem to remember that some (xilinx?) guy has a patent on using > the ldvs input as a comparator for an ADC A simple digital input would do it, too. E.g. with two pins of a microcontroller you can use a standard LED for light emitting and light sensing: http://www.merl.com/reports/docs/TR2003-35.pdf Maybe this could be used with a FPGA, too, for temperature measuring with a 1N4148. But I don't know, if it needs a schmitt trigger input, which is not available for all FPGAs (e.g. only some configuration pins on Cyclone II, but Xilinx FPGAs have schmitt trigger inputs with 100 mV to 200 mV hyteresis). Of course, on page 34 of this journal: http://www.xilinx.com/publications/archives/xcell/Xcell19.pdf there is a simple schematic with only two resistors and two FPGA pins for a user defined schmitt trigger :-) -- Frank Buss, fb(a)frank-buss.de http://www.frank-buss.de, http://www.it4-systems.de
From: John Devereux on 11 Apr 2010 15:56 Joerg <invalid(a)invalid.invalid> writes: > whygee wrote: >> Joerg wrote: >>> I always wondered why FPGA don't have a feature to program an >>> on-chip temperature sensor onto one pin, or at least a diode >>> path. uC often have that, for example the MSP430 series. >> The Actel Fusion family can do pretty temperature measurements, >> but they are ... a bit expensive. >> Maybe a ring oscillator in the FPGA fabric, >> with the output frequency compared to a stable >> external oscillator, can help ? >> > > Sure, but then you have to measure frequency and, for some > applications, you've just created another EMI nightmare. A simple > diode path is all that's needed. In just about any chip design review > I suggest this because the feature is essentially free. What follows > is usually a moment of silence followed by someone saying "Oh yeah, > let's do that". Forward bias one of the protection diodes? -- John Devereux
From: Joerg on 11 Apr 2010 16:15 John Devereux wrote: > Joerg <invalid(a)invalid.invalid> writes: > >> whygee wrote: >>> Joerg wrote: >>>> I always wondered why FPGA don't have a feature to program an >>>> on-chip temperature sensor onto one pin, or at least a diode >>>> path. uC often have that, for example the MSP430 series. >>> The Actel Fusion family can do pretty temperature measurements, >>> but they are ... a bit expensive. >>> Maybe a ring oscillator in the FPGA fabric, >>> with the output frequency compared to a stable >>> external oscillator, can help ? >>> >> Sure, but then you have to measure frequency and, for some >> applications, you've just created another EMI nightmare. A simple >> diode path is all that's needed. In just about any chip design review >> I suggest this because the feature is essentially free. What follows >> is usually a moment of silence followed by someone saying "Oh yeah, >> let's do that". > > Forward bias one of the protection diodes? > Yup, I have used substrate diode for stuff like this but those solutions are often met with outbursts of disgust at design reviews ;-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 11 Apr 2010 16:18 Frank Buss wrote: > langwadt(a)fonz.dk wrote: > >> I seem to remember that some (xilinx?) guy has a patent on using >> the ldvs input as a comparator for an ADC > > A simple digital input would do it, too. E.g. with two pins of a > microcontroller you can use a standard LED for light emitting and light > sensing: > > http://www.merl.com/reports/docs/TR2003-35.pdf > That's real engineering, where competitors look at the circuit and all they can say is "What the hell are they doing here, and how?" [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Frank Buss on 11 Apr 2010 16:26
Joerg wrote: > Yup, I have used substrate diode for stuff like this but those solutions > are often met with outbursts of disgust at design reviews ;-) If you have the space on the board, I would use the SE95, because no calibration is needed. I've used it with high sampling rate and digital lowpass filter for a resolution of 0.01�C. It's fairly stable and intersting to see the temperature falling, when slightly blowing it. I think this could be used for something like this: http://www.coolest-gadgets.com/20060530/electric-candles-that-you-can-blow-out/ :-) -- Frank Buss, fb(a)frank-buss.de http://www.frank-buss.de, http://www.it4-systems.de |