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I have a chip that uses SPI for communication and would like to connect it directly to the USB port on my computer. Does anyone have experience with using a USB to SPI converter? Any recommendations? Quick searches on the web revealed
http://www.robotshop.com/devantec-usb-i2c-spi-serial-interface.html
http://www.sparkfun.com/products/9235
The "FTDI" chip that they use sparkfun product above is typically the easiest way to go.
There is a publicly available "libftdi" (maybe two of them?) that let you talk to the chip via USB. This chip provides a very simple USB-to-GPIO type functionality, and is used to make USB-to-JTAG, Serial, Parallel, CAN, SPI, etc devices.
The FTDI device doesn't require any "programming" - I think you punch a configuration block into it to describe how you want the pins do work, and that's it.
The other alternative is to do what the robotshop product you mentioned does. Use a USB-based PIC controller. This requires you to program the controller, and write your own device driver for your device. Neither of which are very hard, and could offer you more flexibility but a bit more work. Microchip has many PIC variants with built-in USB controllers, and they all have many GPIO lines for you to program into any kind of SPI interface you would want to.
I used the FTDI FT4222H (in the form of a UMFT4222EV-D development board). It converts I2C, SPI, and a few GPIOs to USB. My use case was acting as a high-speed SPI slave (I only needed to read data). Using the LibFT4222 library I was able to get this working on Windows using C# and on Raspberry Pi using C.
https://ftdichip.com/products/ft4222h/
https://www.digikey.com/catalog/en/partgroup/ft4222h-evaluation-module-with-d-version-chip/78324
https://ftdichip.com/wp-content/uploads/2020/07/DS_UMFT4222EV.pdf
https://learn.adafruit.com/usbtinyisp
quite a simple device made with a very popular ATtiny AVR8 (arduino chips should fit). Fully FOSS and ready-made available.
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I have internet connection at my home using a 4G wifi USB dongle, providing the hotspot. Since the service is not always good, I also use a second 4G USB dongle (with sim of a different service provider), when the first connection is down.
I, ideally, want a wifi router, which would take two 4G USB sticks as input, and in turn provide one single wifi network, with the two 4G connections as the backend. The objective is to get seamless internet connectivity (without having to discover internet failure the hard way and without manually switching to the second network).
Are such dual WAN (or whatever they may be called) routers available in the market? Would a Cisco RV320 be a close match to my requirement? In case, there are dual WAN routers available, but with ethernet port instead of USB port, is there an easy way to convert 4G USB dongle to ethernet RJ45 and then use in the router? I am located in India and if the solution is available at Amazon, receiving such link would be great.
What you are referring to is usually termed 'bonding' of internet channels.
It is a common technique to either get higher bandwidth than is otherwise available or to counter availability issues on any one link.
If you search for 'Internet bonding' services or routers you will find examples - e.g.:
https://www.wiredbroadcast.com/products.html#card-mediaport
http://simplybonding.com/examples/mobile-video-streaming.html
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I'm working on a project in which i have to connect a BeagleBoard and an Arduino Pro Mini for communication.
I tried the USB-FTDI way. I have installed all kernel modules, ftdi-sio , usbserial module, but nothing appear in /dev. I try it in Ångström and Ubuntu. I wanted to use I²C, but I have to know electronics. Since the BeagleBoard's GPIOS output is 1.8 V, I need a level converter to communicate with the Arduino.
What do I have to do to make it working?
For I²C, I can think of two solutions readily available.
You can use SparkFun's PCA9306 Level Translator Breakout for I²C. Quote from their web page:
The PCA9306 is a dual bidirectional I²C-bus and SMBus voltage-level
translator that's operational on the low side from 1.0 V to 3.6 V and
on the high side from 1.8 V to 5.5 V. Simply apply your low- and
high-side reference voltages to the VREF1 and VREF2 respectively,
connect your I/O and drive the Enable pin high to open bidirectional
voltage translation without the use of a direction pin!
Or you can SFE Logic Level Converter or like circuit which is a discrete solution. Cheaper and a bit more subtle in its explanation of how it works.
Are you able to detect any USB slaves (mouse, keyboard, etc...) from the host, other than the FTDI? If not, then that would be a place to start.
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I want to develop some HAL (Hardware Abstraction Layers) to use in PIC32 and some ARM.
Basically I want to make some code that's usually available on a OS, like generic pin access, communication libraries, device I/O, etc.
Could you advise me with good books/websites?
I'll start with one that I've found a few weeks ago: http://www.kalinskyassociates.com/OnLineLearning.html
Thanks
Have you tried looking at some implementations?
eCos has a HAL, which has some documentation to go along with it.
eLua also has a HAL that has grown around it to support the platforms it runs on (ARM, AVR32, etc..), check the architecture information and the "Platform Interface" and "Generic Modules" menus. If you strip out the Lua, eLua is essentially a HAL.
There are likely other examples as well, but I'd recommend looking at living examples of cross-platform and non-cross-platform hardware APIs. Also, if/when you go and start putting together interfaces, make sure to examine individual platform peripheral implementations before nailing down the API. You will find that certain interaction models are commonly supported across many platforms, and others are very platform specific. If your API assumes functionality will always be available, it will be difficult to port to platforms that either have lacking or non-existent support for the functionality you want. Sometimes you may be able to work around this in software with simple solutions, other times you may find it is either impossible or horribly complicated to make behavior consistent across platforms.
You can try also looking at the OSEK interface documents. The standard does a good job of abstracting accesses to most commonly used peripherals. However, bear in mind that this is only a spec and you'd have to work out all implementation details.
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I'm new with zigbee i need you to help me learn about it and know how to implement an embedded system using it
thanks in advance
One good place to look is on the Digi site. They have several products to help you, including embedded development kits.
If you want to go Open Source, look at Source Forge. They have some open source stacks. I have not used any of them, so I cannot comment beyond knowing that they exist.
Depending on your needs, you might want to just look at XBee, which is a subset of zigbee. There are some nice development tools for XBee. I have used an XBee expansion shield with the .net micro framework and boards provided by TinyCLR to do a wireless prototype.
Creating a zigbee stack on your own would be a fairly large task, so only you can determine if there is ROI in doing so. I would be more inclined to buy it in.
Get a ZigBee Starter Kit. Lots of vendors provide one; gust Google that exact phrase.
For example: AVR 8-Bit RISC - IEEE 802.15.4/ZigBee - Tools
Or you can ZigBee on a PIC/Microchip at very low cost. http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2112
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I need to read the user's fingerprint from my application.
What I really want is a simple SDK that works with a lot of inexpensive fingerprint readers but I can deal with something that works only with one specific model if that model is cheap and available worldwide.
And it has to be royalty-free, I can pay for a development license but if I have to pay for each installation I just can't use it.
What I'm doing has no relation to login or encryption, so the software included with the reader will probably be useless to me.
There is no standard API for reading fingerprint data as far as I'm aware since it is a fairly new field and there's no standard way of doing it. Each manufacturer will provide their own API for reading the hardware. The API could just be IO specification to the hardware and there's no library whatsoever, which makes things a bit trickier. This is down to two factors. The first is that finger print readers are used in many applications - custom hardware, embedded systems through to PC authentication and beyond. Providing software for all those different systems would not be viable from the manufacturers point of view. Secondly, each manufacturer uses a different approach to reading and processing the captured images which would make a common API problematic.
It's an old question, but I bumped into it while researching the topic.
I did find a free library for Linux - libfprint
Digitalpersona has a free SDKs both for windows and linux.
http://www.digitalpersona.com/products/developer.php
I dont know if there are costs for deploying with their SDKs.
(Actually it appears they don't charge per machine/user licensing.)
Did you take a look at the BioAPI consortium site? There's a library for linux over at Google code.
There's also libchipcard, but it doesn't mention fingerprint readers, only smart cards.
Hope that helps.
Symbol has an api for their MC75 handheld devices:
http://support.symbol.com/support/search.do?cmd=displayKC&docType=kc&externalId=12364&sliceId=&dialogID=104336066&stateId=1%200%20104330426
Of course, it only works for their Windows Mobile 6 MC75 devices.
See Windows Biometric Framework.