uC - Programming

[spirilis]

Nice! Very cool, never really studied PSU design much.
So JP1 basically takes the rectified output of a AC transformer? (the big blue thing)

 

[entropie]

Yes or you can use a normal DC wall wart @ a maximum of 23 Volts. I used the AC trafo tho cause then you can solder a cable to it and plug it into the wall permanently. If you'ld use a normal DC wall wart efficiency would prolly go down too (most of those things get pretty hot in my experience).

Thats the cable european standard soldered onto the trafo:

Here's the layout and partlist. If you have trouble with the german let me know.

 

[spirilis]

Looked at the datasheet for that TS19377 chip. Will file that in the back of my mind if I ever decide to go nuts with high-power white LEDs one of these days

 

[spirilis]

I do enjoy the look of a good home-etched PCB now and then.

(special BoosterPack to provide an FTDI FT232RL based bootloader and/or UART for my Renesas YRPBRX210 promo board... should let me bypass the SEGGER J-Link onboard to reflash the chip using fully open-source tools instead)

 

[entropie]

I do enjoy the look of a good home-etched PCB now and then.

(special BoosterPack to provide an FTDI FT232RL based bootloader and/or UART for my Renesas YRPBRX210 promo board... should let me bypass the SEGGER J-Link onboard to reflash the chip using fully open-source tools instead)

Yes that looks great indeed. Do you have professional etching tools with temperature regulation and oxygen circulation ? I only etch in a petri disc and never get that good results .

Btw I often have noticed in american designs that the ground layer is created with that circle pattern. Why do you do that exactly, to make it look more cool or has it an EMC effect ? Technically if you dont make the ground layer solid you'ld have to use more etching liquid, no ?!

 

[spirilis]

Yes that looks great indeed. Do you have professional etching tools with temperature regulation and oxygen circulation ? I only etch in a petri disc and never get that good results .

Btw I often have noticed in american designs that the ground layer is created with that circle pattern. Why do you do that exactly, to make it look more cool or has it an EMC effect ? Technically if you dont make the ground layer solid you'ld have to use more etching liquid, no ?!

No, I use a set of ziplock bags (board inside a small sandwich bag, that inside a heavy-duty 1qt bag, which is stuffed inside another 1qt bag, at the very end of the etching & cleaning I keep the acid inside the bags, seal them up & put them in a large 1gal heavy-duty bag and throw it in the trash). Also I add Citric Acid to my ferric chloride, helps it etch faster supposedly. Seems to work anyway. Then I sit it down on my workbench and fold the ziplock bag's zipper over and just massage it side to side, sloshing the chemicals around, picking up the whole bag and putting it against the light to see when I'm done.

I think the key for precision is the laminator--I use a laminator to transfer the toner, not a clothes iron.
The ground plane isn't anything fancy, just one of the patterns available in DipTrace (I don't use eagle). I learned most of my home-etching stuff and even my original technique & supplies from this guy -- http://www.pcbfx.com/

He recommended using a crosshatched ground plane to avoid straining the laser printer, i.e. having it dump a lot of toner at once may cause it to deposit a thinner layer which could let a little acid through the etch-resist. In practice that doesn't seem to be the case, and I may just switch to solid ground planes for home work soon. My Samsung laser printer pretty much rocks. Also it's a pain in the ass to get the black toner off the board with the crosshatch pattern--toner likes to get stuck in those little holes. I usually have to pour acetone straight on the board and let it sit a few seconds before scrubbing, once or twice, to get it looking decent.
I doubt the crosshatch has any bearing on EMC (if anything, it may worsen it for double-sided designs, although I don't do any double-sided stuff yet at home, I save that for the professional fabs )

 

[spirilis]

Finally did drill & solder one of those boards, and it works... so now I have fully open-source tools (HW & SW) for flashing the Renesas RX210 chip on the YRPBRX210 promo board from my MacBook Pro. Got it working too, made some custom LD linker scripts to accommodate the RX210's unique differences from its bigger brother (newlib's default rx.ld is tailored for the RX600 series), got an LED blinking.

Now I'm reading about FreeRTOS and bought one of their DRM-restricted PDF book sets (specifically for the Renesas RX600 series plus the reference guide) because I think it's ghetto that I am playing with badass chips like this but doing my own main() loop when this thing could run circles around my MSP430's with multiple threads if only I had an RTOS under the hood.

 

[entropie]

That sounds like great work. Looking into that RTOS thing is intresting for me as well, I guess I'll try it as a new project on the MSP 430. I've been looking into building a more efficient CNC-control than my existing one. Atm I have a board controling the steppers via three L298 bridges, which are an energetic catastrophy. Only really works with a huge heat sink and a an extra fan :/. Plus the control needs an analog signal from the computer, which is impossible to generate regarding Realtime capability. I bought a 10 year old PC on ebay for 5 Euro, which was the only machine able to move my steppers at all via a somewhat realtime parallel port.

Maybe with an RTOS sitting on the chip, I can control it digitally from the PC. That would be already possible with an AVR, but looking into that new chip would be more fun. Especially concerning all the additional gadgets it has. I am gonna take a look at the FreeRTOS windows emulator, gonna see how that works.

Meanwhile I had my printrbot imported and assembled. Here are some first prints:



I need a fan to cool the plastic while printing, its pretty non-heat resistant and the results aint too precise yet. With a fan tho that should be better. Printing is a lot of fun, you should really try it. PTC just released a free CAD-program and I'll use that to build some boxes for my electronic projects. Only the sky is the limit when it comes to finding ideas on what to print in that case

 

[spirilis]

That sounds like great work. Looking into that RTOS thing is intresting for me as well, I guess I'll try it as a new project on the MSP 430. I've been looking into building a more efficient CNC-control than my existing one. Atm I have a board controling the steppers via three L298 bridges, which are an energetic catastrophy. Only really works with a huge heat sink and a an extra fan :/. Plus the control needs an analog signal from the computer, which is impossible to generate regarding Realtime capability. I bought a 10 year old PC on ebay for 5 Euro, which was the only machine able to move my steppers at all via a somewhat realtime parallel port.

Maybe with an RTOS sitting on the chip, I can control it digitally from the PC. That would be already possible with an AVR, but looking into that new chip would be more fun. Especially concerning all the additional gadgets it has. I am gonna take a look at the FreeRTOS windows emulator, gonna see how that works.

Meanwhile I had my printrbot imported and assembled. Here are some first prints:



I need a fan to cool the plastic while printing, its pretty non-heat resistant and the results aint too precise yet. With a fan tho that should be better. Printing is a lot of fun, you should really try it. PTC just released a free CAD-program and I'll use that to build some boxes for my electronic projects. Only the sky is the limit when it comes to finding ideas on what to print in that case

So far it looks like FreeRTOS isn't much more than a simple scheduler and a library of code to implement reasonably canonical device drivers (queues, semaphores, etc)... so it's just a fancy addition to what we typically write on MCUs like the AVR and MSP430. I guess you could implement a lot on top of it and use it as the infrastructure for a far more sophisticated system employing TCP/IP, USB, etc... In any case I suspect using an RTOS platform is a small but useful step up in laying the foundation for your applications.

Alas, a well thought out system to allow an MCU to control your CNC rig should be a boon no matter what (a PC twiddling its parallel port always screams "ghetto" to me ... lol), and an RTOS will probably help with that. Guess the big choices will involve how much RAM the mcu needs and that'll probably decide what kind of controller you use... MSP430's tend to be rather small although they just recently announced a new expansion of the "value line" series to 56K flash/4K SRAM, and the higher-end F5xxx series of MSP430 I think is less cost-effective for what you get (there's a thread about that here, good read.)

It does sound like STM is really killing the market with their ARM-based MCUs. The STM hobbyists all seem to be more hardcore folks who do this stuff for a living though. My Renesas RX effort is a bit of a lark, I haven't found many folks at all who tinker with Renesas chips in their spare time... but the hardware is pretty comparable to what STM's put out at least. I have 2 Renesas boards laying around that have 96KB and 64KB RAM on them, respectively, and their later offerings go even higher.

 

[spirilis]

I'm in for 2 of the new BeagleBone Black....
http://beagleboard.org/Products/BeagleBone Black

Somewhere I'd read it estimated that the CPU used in the BBBlack should be roughly 2x the performance of the Raspberry Pi's CPU. (edited) Looks like its GPU is about 1/2 the performance of the RPi's, at 20M-polygons/sec vs. RPi's 40. Not sure what that means in terms of actual media playback capability et al; the BBBone's is comparable to the iPhone 4 GPU I believe. Has microHDMI output with audio support soon (needs a driver update I think).
Mine should ship 5/13. Includes a boatload of I/O on its headers; 5 UARTs, CAN, tons of GPIOs, an ADC onboard that works up to 1.8V (the rest of the I/O is 3.3V), etc. I'm gonna keep one for tinkering and one for projects... probably on my desk @ work as a low-power server. I have some ideas for building a remote RF-enabled terminal for carrying around the office.

 

[spirilis]

Got my BeagleBone Black's already! It shipped a couple days ago and arrived today, well ahead of original schedule...

Definitely a cool gadget, currently running through the default stuff running on it, it sets up a USB network link (musb-hdrc I think it calls it) with the local PC and runs a dhcp server so the attached computer can contact it (PC 192.168.7.1, beaglebone black 192.168.7.2). Has some Node.js-based system for writing Javascript applications in an arduino-esque dialect to control it.

From what I've read so far the GPU does not do hardware accelerated media encoding/decoding, only 3D and OpenCV type of stuff. So it's probably not the best choice for an XBMC media console, something a lot of folks seem to get excited over (since the RPi does work well for that I've heard). But this is all general theory crap I've read, the proof is in the pudding as they say... MPlayer is installed by default so I may take a crack at viewing some videos over its HDMI link later. I'm guessing all the decoding has to happen in software on the main CPU. The CPU does support an extended floating point instruction set called "NEON" and I don't know if MPlayer makes use of that.

 

[entropie]

Hmhm looks good that board, clearly a reaction to the RPi, I remember skipping the intrest on beaglebones cause they had been rather expensive. I am running two RPis with XBMC for two televisions and they are pretty good for watching documentaries and all sorts of english movies via video link aggregators. The only problem is a strange glitch the RPi has in combination with my Audio Video Receiver. I had a RPi version 1 and version 2 and the first one worked with no problems with the AVR and TV but the second one seemed to have a bridged 5V logic input on the HDMI connector. Cause even when it was powered off but physically connected to the AVR it made the AVR turn off and dont switch on again. Strangely now after a recent XBMC update I have the same troubles with version 1.

Another thing that sucks for XBMC usage is boot time. Ok 10 seconds is fast but it could be faster. I have build an own Arch Linux distribution and installed XBMC on it but that frontend is so loaded with junk that the boot time didnt decrease dramatically. If you manage to get xbmc running in a good quality on the beaglebone black lemme know, maybe thats an alternative then.

 

[spirilis]

Hmhm looks good that board, clearly a reaction to the RPi, I remember skipping the intrest on beaglebones cause they had been rather expensive. I am running two RPis with XBMC for two televisions and they are pretty good for watching documentaries and all sorts of english movies via video link aggregators. The only problem is a strange glitch the RPi has in combination with my Audio Video Receiver. I had a RPi version 1 and version 2 and the first one worked with no problems with the AVR and TV but the second one seemed to have a bridged 5V logic input on the HDMI connector. Cause even when it was powered off but physically connected to the AVR it made the AVR turn off and dont switch on again. Strangely now after a recent XBMC update I have the same troubles with version 1.

Another thing that sucks for XBMC usage is boot time. Ok 10 seconds is fast but it could be faster. I have build an own Arch Linux distribution and installed XBMC on it but that frontend is so loaded with junk that the boot time didnt decrease dramatically. If you manage to get xbmc running in a good quality on the beaglebone black lemme know, maybe thats an alternative then.

Yeah I'm not too optimistic about the XBMC use case, the GPU doesn't have the video codec stuff so it wouldn't be able to play HD video... maybe 480p but that's about it. So far I have updated the packages on the device, managed to brick it so it won't boot, hooked up an FTDI serial cable to the console to unbrick it (update refused to install kernel-image-3.8.8 b/c its files would overwrite those provided by kernel-image-3.8.6, wth) and now I'm settling in with its CLI. Also thinking about learning the Node.JS Bonescript stuff just so I can write cool shit others can use easily.

 

[entropie]

How is it going with the beagleboard ?

Take a look at this one: Toshiba M370: http://www.toshiba-components.com/microcontroller/TMPM370.html

Intresting as well, tho prolly a bit oversized for most of my BLDC applications

 

[spirilis]

How is it going with the beagleboard ?

Take a look at this one: Toshiba M370: http://www.toshiba-components.com/microcontroller/TMPM370.html

Intresting as well, tho prolly a bit oversized for most of my BLDC applications

Got the renesas RX cross compiler built, haha, everyone on IRC tells me I should build an ARM x-compiler on my mac so I can do a canadian cross (cross-compiler built with a cross-compiler) instead...

It also looks like the Node.JS/Bonescript support for the hardware is in flux; with the BBBlack they moved to kernel 3.8 which introduces Devicetrees as the mandatory way of configuring the pinmux settings, the released firmware doesn't support that yet. Old version of the beaglebone used an "omap_mux" debug driver which is long gone now. Also one quirk, you have to place a "uEnv.txt" file on your SD card or else the bone won't boot at all if you insert the SD card and reboot; plus it's not hot-pluggable, you have to boot it up with the SD card installed. Minor annoyances like that so far. Otherwise it's pretty cool! I'll get around to learning Bonescript after the next firmware update or 2 I guess... wait for the quirks to get worked out. Also managed to sell 2 of my 4 to coworkers.

 

[entropie]

Working on a very small AVR-webserver project using the uip library. So far the board layout is about 1,77 x 1,77 inches, which should fit into a box of matches. A micro SD-card will be added as well.

The thing should be used as a data storage primarily, which I can access via USB or thru the internet. I am planning to make connectors for all the remaning AVR ports so I can add a webcam for cat surveillance or maybe a relais for switching things on and off. So a starting project for home automation. Doing this with an AVR to get a better grip on the basic hardware and software involved in such a project.

I have looked into powering the thing via PoE but those standard is a mess. Hardly any routers availiable at all which support it and dont cost a billion and just using a switch cable to power it is no solution yet.
I have used one of these magjack RJ45 ports now, which have the necessary HF-trafo integrated.