Hi all, I am working on a project where I need some 16 bits ADC to retrieve information from a sensor. I also need a small microcontroller such as a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around $5 (qty 1000), which is 5 times more expensive than the controller! Does anyone have an idea about how I can get some low cost ADC- Controller solution? I need only few dozens of samples per second, so some of you may have nice tricks to do that (op-amps, capacitor charge time stuff and the like). Thanks, Bruno
16-bits ADC anyone?
Started by ●June 5, 2007
Reply by ●June 5, 20072007-06-05
"Bruno Richard" <bruno.richard.fr@gmail.com> wrote in message news:1181030631.316540.197960@g4g2000hsf.googlegroups.com...> Hi all, > > I am working on a project where I need some 16 bits ADC to retrieve > information from a sensor. I also need a small microcontroller such as > a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around $5 > (qty 1000), which is 5 times more expensive than the controller! > > Does anyone have an idea about how I can get some low cost ADC- > Controller solution? I need only few dozens of samples per second, so > some of you may have nice tricks to do that (op-amps, capacitor charge > time stuff and the like).You might want to look at sigma-delta type converters. They often offer much better than 16 bits at ~100 Hz, and generally cheap. Peter
Reply by ●June 5, 20072007-06-05
Bruno Richard wrote:> Hi all, > > I am working on a project where I need some 16 bits ADC to retrieve > information from a sensor. I also need a small microcontroller such as > a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around $5 > (qty 1000), which is 5 times more expensive than the controller! > > Does anyone have an idea about how I can get some low cost ADC- > Controller solution? I need only few dozens of samples per second, so > some of you may have nice tricks to do that (op-amps, capacitor charge > time stuff and the like).Try something like the Silabs C8051F353R ? Shows as $3.48/1500 pcs at Digikey. -jg
Reply by ●June 5, 20072007-06-05
Bruno Richard brought next idea :> Hi all, > > I am working on a project where I need some 16 bits ADC to retrieve > information from a sensor. I also need a small microcontroller such as > a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around $5 > (qty 1000), which is 5 times more expensive than the controller! > > Does anyone have an idea about how I can get some low cost ADC- > Controller solution? I need only few dozens of samples per second, so > some of you may have nice tricks to do that (op-amps, capacitor charge > time stuff and the like). > > Thanks, BrunoTake a look at BB ADS1100 that works 16bit @ 8SPS. It has I2C interface (just 3 bytes to retrieve HIGH/LOW word of converted value and the status register) and I think it's around 2/3 euros. http://focus.ti.com/docs/prod/folders/print/ads1100.html Bye!
Reply by ●June 5, 20072007-06-05
On Tue, 05 Jun 2007 08:03:51 -0000, Bruno Richard <bruno.richard.fr@gmail.com> wrote:>Does anyone have an idea about how I can get some low cost ADC- >Controller solution? I need only few dozens of samples per second, so >some of you may have nice tricks to do that (op-amps, capacitor charge >time stuff and the like).The Texas Instruments MSP430 microcontroller has 16 bit ADC on chip. In quantity, it should be in the $3 to $5 range depending on which version you need. I think Analog Devices has 8051's with 16 bit ADC. You might also look at Maxim. I seem to recall that they have gotten into microcontrollers with high resolution ADCs.
Reply by ●June 5, 20072007-06-05
"djordj" <djordj@despammed.com> wrote in message news:mn.2b827d762792088b.73215@despammed.com...> Bruno Richard brought next idea : >> Hi all, >> >> I am working on a project where I need some 16 bits ADC to retrieve >> information from a sensor. I also need a small microcontroller such >> as >> a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around >> $5 >> (qty 1000), which is 5 times more expensive than the controller! >> >> Does anyone have an idea about how I can get some low cost ADC- >> Controller solution? I need only few dozens of samples per second, so >> some of you may have nice tricks to do that (op-amps, capacitor >> charge >> time stuff and the like). >> >> Thanks, Bruno > > Take a look at BB ADS1100 that works 16bit @ 8SPS. > It has I2C interface (just 3 bytes to retrieve HIGH/LOW word of > converted value and the status register) and I think it's around 2/3 > euros. > > http://focus.ti.com/docs/prod/folders/print/ads1100.htmlSeconded. You certainly want sigma-delta, and you certainly want ratiometric. This device does both in a rather nice package. Steve http://www.fivetrees.com
Reply by ●June 5, 20072007-06-05
On Jun 5, 3:03 am, Bruno Richard <bruno.richard...@gmail.com> wrote:> Hi all, > > I am working on a project where I need some 16 bits ADC to retrieve > information from a sensor. I also need a small microcontroller such as > a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around $5 > (qty 1000), which is 5 times more expensive than the controller!You might see what you can accomplish by using a cheap micro witha 12- bit ADC and a lot of careful filtering (averaging) in software, since your needed sample rate is quite low. It might not get you 16 real bits, but if unit cost is a driver, figuring out if the accuracy it can get you would be enough is probably worth the effort.
Reply by ●June 5, 20072007-06-05
>On Jun 5, 3:03 am, Bruno Richard <bruno.richard...@gmail.com> wrote: >> Hi all, >> >> I am working on a project where I need some 16 bits ADC to retrieve >> information from a sensor. I also need a small microcontroller such as >> a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around $5 >> (qty 1000), which is 5 times more expensive than the controller! > >You might see what you can accomplish by using a cheap micro witha 12- >bit ADC and a lot of careful filtering (averaging) in software, since >your needed sample rate is quite low. It might not get you 16 real >bits, but if unit cost is a driver, figuring out if the accuracy it >can get you would be enough is probably worth the effort. > > >In this vein, you may want to check the SiLABS application note AN118 called "IMPROVING ADC RESOLUTION BY OVERSAMPLING AND AVERAGING" http://www.silabs.com/public/documents/tpub_doc/anote/Microcontrollers/Precision_Mixed-Signal/en/an118.pdf
Reply by ●June 5, 20072007-06-05
Bruno Richard schrieb:> I am working on a project where I need some 16 bits ADC to retrieve > information from a sensor. I also need a small microcontroller such as > a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around $5 > (qty 1000), which is 5 times more expensive than the controller! > > Does anyone have an idea about how I can get some low cost ADC- > Controller solution? I need only few dozens of samples per second, so > some of you may have nice tricks to do that (op-amps, capacitor charge > time stuff and the like).You can build a cheap & simple dual slope converter with an external reference (like TL431), MUX (4051), integrator and comparator (standard OP). With an 8051, you can generate the fixed integration time and measure the variable deintegration time with only one of the internal timers, while the signal from the comparator provides the timer gate signal and the EOC interrupt at the same time. (I don't know if other micros also have 16 bit timers with external gate signal that also can generate edge triggered interrupts without additional pin.) With very cheap standard parts, we have made 15 bit ADCs this way. You also get line frequency suppression by proper selection of the integration time (we tend to use 100 ms to suppress both 50 Hz and 60 Hz, which gives a total conversion time of 200 ms - or sync it to the mains and integrate 16.7 resp. 20 ms), which is often needed for sensor signals. You can use the other 4051 inputs (or even two or more 4051s) for more input channels, which can be converted sequentially. Slow, but reliable. Tilmann -- http://www.autometer.de - Elektronik nach Ma�.
Reply by ●June 5, 20072007-06-05
On 2007-06-05, Bruno Richard <bruno.richard.fr@gmail.com> wrote:> I am working on a project where I need some 16 bits ADC to retrieve > information from a sensor. I also need a small microcontroller such as > a PIC, AVR or 8051, and I got surprising quotes for the ADC: Around $5 > (qty 1000), which is 5 times more expensive than the controller! > > Does anyone have an idea about how I can get some low cost ADC- > Controller solution?There are versions of the TI MSP430 that have 16-bit S-D ADCs. www.msp430.com -- Grant Edwards grante Yow! I selected E5 ... but at I didn't hear "Sam the Sham visi.com and the Pharoahs"!
