Um, what's the ballpark price target then, for assorted devices under discussion? I suggest $30 total circuit cost as a target, not counting mechanical. Don't forget the CCD if any, unless using photodiodes. Raspberry Pi is not too good for controlling I/O: can be seen by the projects adding on additional boards beyond the Pi. "Low cost" seems to be frequently bandied about here, yet the result seems not very low cost at all. And transferring very little bandwidth does not need expensive networking components. Again, the lab devices don't move, so they can be connected to a nearby computer for the network connectivity/apps (labs have cheap computers, plenty of them), and the amount of data transferred is very small (kilobytes not megabytes, and speed is not required anyway).
Ref: http://www.horizonpress.com/pcr/qPCR-machines.html
"""The following PCR machines are compared for various features to help you decide which instrument is most suitable for your needs. ... ABI StepOne, LightCycler 480, Mx4000, Rotor-Gene 6000, Mastercycler, MiniOpticon, MyiQm, Chromo4, iQ5"""
Sure, go add wireless to it. Then be prepared to pay several thousand minimum to get it certified by the FCC for RF emissions. Oh, it's OK, you'll just amortize that cost into the devices' selling price. Wait, the idea was to be low cost, oops again. And now it requires a $600 Android phone to be used? Yikes, stop the insanity.
## Jonathan Cline ## jcline@ieee.org ## Mobile: +1-805-617-0223 ########################
On 5/22/13 4:46 PM, Simon Quellen Field wrote:
We may have different definitions of low cost.:-)
You can get WiFi, a touch screen, and USB (which gives you Ethernet if you add an $8 dongle) all in a nice tablet package, for $56, including shipping.
Starting with that, adding a $3 microUSB to female USB connector, and writing some Android software, you can control a $10 TI MSP430 Launchpad (an Arduino on steroids) using the Android USB hosting feature.
So far, we're up to $70 to add WiFi and a touchscreen (and we also get local storage, a 1 GHz processor, programmability, and a much better user interface experience than a keypad and LCD display).
The devices you want to communicate with (laptops and the cloud) don't have RS232 serial ports. But they do have WiFi and USB, both of which are much faster.
I get my Internet here on the mountain using WiFi. My dish is aimed at a dish 4 miles away. So range is not an issue (and of course WiFi is isolated -- no wires). But once you have the Android tablet, range is not an issue anyway, since you are on the 'net, and anyone in the world can get to the data. The tablet can run an Apache server and serve the data itself.
A USB to RS232 adapter is more than $10, and is slow (most won't do more than 0.1 megabits). To do file transfers over it requires writing software, and adding error correction slows it down even more. With USB or WiFi, you just drag and drop the data, and it is error corrected. The Android tablet looks like a disk to your laptop, and looks like a web server to your browser. Controlling it and getting data to it and from it is a lot easier and faster using WiFi or USB than any RS232 solution.
Since the laptop already speaks USB and WiFi, why convert USB to slow serial, and lose all those advantages?
Of course the device doesn't need a touchscreen if it has WiFi and a Linux OS.Use a $25 Raspberry Pi and a $10 WiFi dongle, and put the user interface in a web page on the Pi.Now you control it with a laptop or a smartphone, using a web interface.And you don't need another microprocessor, the Pi has GPIO pins accessible to control lights, motors, and servos.If you want to save the $10, omit the WiFi dongle and just plug the Pi into your laptop's USB and set it up as a network device.--
On Wed, May 22, 2013 at 12:07 PM, Jonathan Cline <jncline@gmail.com> wrote:
On Monday, May 20, 2013 4:05:12 PM UTC-7, Josh W. Perfetto wrote:Ashley, the plan is to provide a very low-cost unit, ....very friendly software accessible
via wifi/ethernet/touch screen.
Low-cost is not synonymous with providing these expensive system components (wifi/ethernet/touch screen). Don't even mention using likewise expensive & underwhelming arduino. $10 here, $10 there, it all adds up and is not very low cost. USB is a better bet, serial still the cheapest and simplest. For an automation system, a better bet is industrial grade wired bus with longer distance. Lab equipment typically doesn't move or alternatively if it's a field unit, it is plugged into a computer after logging data internally.
Here's typical options for low cost communication. It's probably better to have independent power rather than run power through the communication link.
RS-232 - UART framed, single ended, full duplex, non shared media, NRZ, up to a few hundred feet, non powered, non isolated.
RS423 - UART framed, single ended, full duplex, non shared media, logic level, several hundred feet, non powered, non isolated.
RS-422 - UART framed, differential, full duplex, non shared media, logic level, up to a thousand feet, non powered, non isolated.
RS485 - UART framed, differential, half duplex, shared media, up to a couple thousand feet, non powered, non isolated.
CAN/Fieldbus - UART framed, differential, half duplex, NRZ, powered, signal can be isolated.
GPIB/IEEE-488 - parallel bus, logic level, short-range, shared media, high bandwidth, ruggedized connectors, very common in tech equipment, more expensive connectors & cabling in comparison to the others.To view this discussion on the web visit https://groups.google.com/d/msgid/diybio/06c8c217-1410-4ce8-b09c-80d59b4cda88%40googlegroups.com?hl=en.
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