Wifi: Connecting a Laptop to en embedded system
in [Design]
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From: Jan Panteltje on 15 Jun 2010 12:39 On a sunny day (Tue, 15 Jun 2010 18:14:29 +0200) it happened "PovTruffe" <PovTache(a)gaga.invalid> wrote in <4c17a704$0$28656$426a74cc(a)news.free.fr>: >"Jan Panteltje" <pNaonStpealmtje(a)yahoo.com> a �crit : >> Questions you need to answer here first: >> 1) Does it need 1 way or 2 way communication. >> 2) What speed >> 3) What interfaces are available on the embedded system, and what interfaces are available on the PC. >> 4) Distance >> 5) Reliability. > >The requirements are very low: >1) Just a few bytes (commands) sent to the embedded system once a while. > Thats one way communication but I dont know yet if status data may be > necessary or even usefull (I am just starting to think about the project). >2) Very low speed but reaction time should not be too low. >3) Any interfaces that could be made available on a 16 bit PIC driven board. >4) Very low distance: max 20m (60ft...) >5) This is not a mission critical system > >The embedded system would already have a control panel so the wifi >connection could just be used by some customers who would use their own >laptop. You say a PIC board. To do the WiFi thing I think you need a wireless adaptor, and a TCP stack. As somebody already suggested, hack a WAP654G and you have it all, WiFi, but with a MIPS processor, programmable in C. http://panteltje.com/panteltje/wap54g/index.html#wapserver I am not against PICs, I use those, but you cannot beat this for price (65 Euro). I have some I/O on it too, analog and digital, with - yes - a PIC. 20 m is not really 'short distance', that rules out IR and probably cheap 430 MHz modules. If you want to stay with PIC only then there is a free microchip TCP stack somewhere. There are also small ARM based modules available sith TCP, complete ones for under a hundred Euro I have seen annouced. >Therefore the laptop could be of any type. My idea is that using wifi >could be the easiest solution for this kind of application (or not?). > >> For example for a one way low bitrate short distance you can hang a >> 430 MHz module on the serial port, and dream up some protocol. > >Yes but how many laptops have a serial port nowadays ? >In addition most customers dont even know what a serial port is... I use a USB to serial adaptor (several actually.
From: PovTruffe on 15 Jun 2010 12:48 "D Yuniskis" <not.going.to.be(a)seen.com> a �crit : >> The embedded system would already have a control panel so the wifi >> connection could just be used by some customers who would use their own >> laptop. Therefore the laptop could be of any type. My idea is that using wifi >> could be the easiest solution for this kind of application (or not?). >> >>> For example for a one way low bitrate short distance you can hang a >>> 430 MHz module on the serial port, and dream up some protocol. >> >> Yes but how many laptops have a serial port nowadays ? >> In addition most customers dont even know what a serial port is... > > USB serial port. > > Any reason why you can't use USB *directly* (i.e., why > does it have to be wireless?) A cable might be used but wireless is a feature of the higher end version of the system (customers willing to pay more for this version). However if wifi is too complicated or too expensive I might end up chosing a simple RF USB dongle. > Does the exchange have to be interactive? (i.e., can you use > some intermediary to carry data/commands back and forth -- like > a thumb drive?) Yes, ideally customers should not feel any reaction time when a command is sent to the system from a laptop. I have no idea however if wifi is appropriate in this respect.
From: hamilton on 15 Jun 2010 13:20 On 6/15/2010 8:38 AM, D Yuniskis wrote: > (assuming your embedded system wants to bear the cost of WiFi) I have wondered about this very thing. If an embedded system has to purchase a wireless connection and a PC needs to purchase a wireless connection, what is the cheapest way of do this. The cost of WiFi on an embedded system is large, but Bluetooth is not far behind. Laptops have WiFi but not always Bluetooth. So would two Bluetooth devices be cheaper that one embedded WiFi ?? There is also the cost of software in the embedded system. hamilton
From: hamilton on 15 Jun 2010 13:23 On 6/15/2010 9:12 AM, PovTruffe wrote: > "D Yuniskis"<not.going.to.be(a)seen.com> a �crit : >> PovTruffe wrote: >>> "D Yuniskis"<not.going.to.be(a)seen.com> a �crit : >>>> Um, serial port? (IrDA if you insist on "wireless") >>> >>> It has to be wireless for this application. As far as I know not so many >>> laptops are equiped with IrDa where the vast majority are wifi enabled. >> >> Use an IrDA dongle -- via a serial port, parallel port, USB serial, >> etc. > > It was my first idea to plug some kind of hardware but I thought maybe > there was a better solution without having to add anything... > >> If you want to use WiFi, then configure for an ad hoc network >> (assuming your embedded system wants to bear the cost of WiFi) > > There is no such thing as a wifi network (as I already explained...) unless I These is alway an "ad hoc" network. Do you mean, there is no router ? Don't need it.... http://en.wikipedia.org/wiki/Wireless_ad_hoc_network hamilton > create one with the embedded system I need to control. Maybe there is no > need for a so called network for point to point communication. I dont know > anything about the wifi standard and so dont have any preconceived ideas > of what is possible or not. > >
From: D Yuniskis on 15 Jun 2010 13:42
hamilton wrote: > On 6/15/2010 8:38 AM, D Yuniskis wrote: > >> (assuming your embedded system wants to bear the cost of WiFi) > > I have wondered about this very thing. > > If an embedded system has to purchase a wireless connection and a PC > needs to purchase a wireless connection, what is the cheapest way of do > this. > > The cost of WiFi on an embedded system is large, but Bluetooth is not > far behind. > > Laptops have WiFi but not always Bluetooth. But, cell phones have BT (though you have to be picky about which profiles you expect to work!) > So would two Bluetooth devices be cheaper that one embedded WiFi ?? BT is power hungry. Reasonably high bandwidth. Not as long range as WiFi. BT stack is... let's say "annoying"? :) > There is also the cost of software in the embedded system. ZigBee. Low power, long range, variable data rates, reasonably simple stack, inexpensive (comparatively speaking) etc. |