I also made a small casing for my PCB, first time ever I used Sketchup, think it came out alright :) Here are some pics: Project is still busy, it will be a CMSIS-DAP ARM debugger, will post something about it on http://www.simplecortex.com in a week when all tests are done :) Sneak peek for you guys ;)
I made this report for my internship, it has some basic tips on how to use Eagle for 4+ layer PCB and some tips in general. I think it can be useful even if you don't use Eagle, so why not share it ;) You can find it here: http://www.brc-electronics.nl/forum-mai ... layers#193
For making the Simplecortex beta boards we decided to use a Solder stencil from Itead. They cost 45 dollars but it saved us 20 minutes per board applying solder paste. And at 10 boards that adds up... Here some photo's (last photo is a bit messy, was to lazy to clean it :) )
For our final year school project two classmates and I decided to make a ARM Cortex dev board. We made it because the Arduino(required by school) lacks stuff like debugging and a powerful IDE. When making big (school)projects this can get a bit annoying. At my last internship at NXP semiconductors I learned to work with the ARM Cortex devices made by NXP. Also I discovered the CooCox programming environment and debugger. All this combined and 5 months of hard work later the dev board, called the Simplecortex came out :)
NXP and our school liked it a lot so we contacted Iteadstudio to see if they would be interested in making it. Luckily they liked it to and with the help of Iteadstudio it is now officially released. The Simplecortex has an Arduino compatible layout and uses an Eclipse based IDE. To make it simple to use we made a bunch of tutorials and libraries to get people started. It also has some cool stuff onboard like MicroSD and Ethernet. Our website can be found here: http://www.simplecortex.com
To be honest, none of us is good at webdesign and the release was earlier then planned. So the website is still in beta and hard to find with Google. We are working on that at the moment. All tutorials and such is online, so the most important part is there :) Most info can be found on our website but if you have any questions please ask. This is all quite new for us (actually selling something we made) so critique is welcome, just be gentle please :)
i saw something interesting in my email from elektor. they tested a TI dev board and came up with a benchmark to define how easy to use a microcontroller board is. i like the idea becouse some dev boards are easy to use and some are a pain in the ass. there benchmark is quite simply: biggest HDD available / size of included IDE (mouse clicks before it works * icons on desktop) maybe not the best benchmark (nothing about included documentation and examples) but i like the idea. more info is on there blog: http://elektorembedded.blogspot.com/201 ... t-and.html
now, how much hw's does you're favorite dev board gets :D
yes i am out of flux and yes i hand soldered those 0.4mm IC's WITH ground plane on the bottom :) i got another 2 with all pinheaders installed. becouse these CPLD's are just 2 dollars i made some extra.
disclaimer: this project wont be done next week, nor even next month. its a summer holiday project so i will seriously start with it after 4 juli when my 7 weeks of nothingness begins :D i hope its OK to post a not done project, i will add stuff while making it so i end up with a good log of the whole project.
I want to make a USB scope, but you could have guessed that from the title. I also want to make it quite cheap, I aim for 50 euro's to make one as a school project we are already making a simple scope but its rather limited in speed and use, 1Msps is kinda slow :) but we got the scope part working, only the software is left to do. but 1Msps is really not useful, effective bandwidth for looking at a sine wave is maybe 50Khz.
Then i saw the scope project from DP(Dangerous Prototypes) That looks a lot better, 50Msps means 3 to 5 MHz usefulness bandwidth for looking at sine waves. But then its single channel, uses a Xilinx FPGA and a Picmicro for USB transfer. Single channel is an easy fix, add another ADC. I personally work with altera CPLD's so i wont use a Xilinx device and i will use a CPLD and not a FPGA. As a CPLD is a lot smaller then a FPGA i will need to have a separate SRAM IC for buffering. Not a real problem, 64 or 128K ram is less then 5 euro's, even 10nS speed SRAM.
I never used a Picmicro for USB transfer, i only used 16F 8 bits Picmicro's until now. I have used FTDI devices before, the normal FT232 but also the very fast FT2232H so USB transfer is not a problem. I have some good experience with high speed analog design, tip for DP, even a 1pf capacity between the inputs of the ADC and the ground can be troublesome. So removing a piece of the ground plane underneath the inputs of the ADC can help a lot for analog performance :) All with all, in theory i should be able to make a scope, only the PC software is a bit hard for me. The whole project will be open source so if someone else can help with the software it would be awesome.
Until now I only have design ideas on paper. When my summer holiday starts I want to have a PCB design done so I can give Iteadstudio something to do :) Design ideas:
2 ADC's, ADS830@ 50Mhz 2 speedy op-amps, TI has some nice ones for a low price 1 SRAM Buffer, 64KByte, at least 10ns speed 1 CPLD, EPM570 from altera, fast enough and because the SRAM is a separate IC its is probably big enough. A CPLD doesn’t need a SRAM IC to load code from so CPLD + SRAM is a bit cheaper then an FPGA. 1 FT232 in bitbang mode for a max of 12Mbit USB transfer speed. I could use a FT2232H but that one is double the price of a FT232 A better 5V and -5V power supply than the USB ones.
And thatch about it :)
Buffer chaos well I need a buffer, 2 ADC's at 50Mhz create a 100MByte per sec dataflow and its madness to send that trough USB. I normally get 10 to 12MByte with a FT2232H, 100Mbyte is USB3 range and roughly impossible to do as a student.
I will use a FT232R in bitbang mode, 4 I/O for data and 4 for handshaking/setting trigger/other stuff at 12Mbit I will have ~750Kbyte per sec with 4 I/O ports. With a 64K buffer it means I can send it trough USB more then 10 times per second. Enough, not going to mess with that :)
but 64K buffer means 32K per channel. At 50Mhz that’s just 640uS of data, seems really tiny right? Now image you are looking at a 1Mhz sine-wave signal, one sine-wave is then 1uS you can fit 640 whole sines in that buffer, more then enough it seems now imagine looking at a 1Khz signal, that’s 1mS for one sine-wave Now you can't even fit one sine-wave in the buffer, that’s bad! The solution is simple, you can lower the speed of the ADC or lower the speed that the buffer saves the data. Both solutions do the same, making the ADC run 100 times slower or just saving one in every 100 samples to the buffer, both ideas slow the whole thing down by 100 times. When everything is slowed down 100 times you can fit 64mS in the 32K buffer, a lot better. Then 1Khz isn’t a problem anymore.
Like I said in the top of this slightly to long post, this wont be done in a month. I want to have it done in begin august when school starts again. The whole project will be open source and if it actually works and people want it I might poke seeedstudio about selling them.
That’s it for today, when I have more info about anything related to this project I will make another massive post ;) I will try to connect a ADS830 to a FT2232H directly next week, ADS @ 6 to 10Mhz so I don’t need any form of a buffer and see what happens. Ideas, please share them :)
i got this in a lattice newsletter per e-mail today. a big PCB with a big FPGA and a fast PCI-E connection for just 99 dollars. after some googeling i found the quickstart PDF from it, it looks like good value for money but not for beginners. so if you ever had the urge to develop your own video card or network card, well today's your lucky day :)
in the user guide is a big picture of the dev kit, anyone else see a FT2232 for USB programming ;) well, who's the first to make a lattice programmer :) http://www.latticesemi.com/documents/EB62.pdf
i got a problem installing the FTDI drivers with a FT2232H device. i am using a mini module from FTDI on windows 7 home prem ium (cant spell it right, forum thinks it spam) 64 bits. when i plug in the device windows automatically installs the usb composite device driver. if i update the drivers to the FTDI drivers windows states the composite device driver is newer and wont install the FTDI drivers. when i uninstall the composite device driver windows automatically reinstalls them!
MProg doesnt work with the composite drivers, really annoying. we kinda need the FT2232 to work for our school project (making a USB scope) so if anyone knows a solution it would be great.
Rik
//edit// ok, new problem, the whole board seems dead. my PC running windows ultimate doesnt detect anything. time to send it back to farnell :( //edit//
