Decent hobby level mcu for DSP - Page 1
Forum section: electronics / beginners

author: Dajgoro
author_rank: Frequent Contributor
timestamp: August 19, 2013, 06:01:16 pm
content: Hi.For a whine now I've been wondering what would be a decently adequate MCU for doing some digital signal processing stuff like DCT algorithms and such.Well, the Intel 8031 is no choice at 1MIPS, modern 8 bit micros can give up to 16MIPS, and those dsPIC can give even more. Problem is that I am doing homebrew experiments, and something in a tiny smd package that runs only at 3.3V is not very friendly. I also only have a Pickit2 programmer and a universal programmer which is good for all of the older chips.I remember that there were some ARM chips in DIP packages, and I do have a LPCxpresso board with the usb programmer module attached to it.The smd factor isn't always a big problem if adapter boards can be found on ebay. I usually have bigger issues with 3.3V since all of my other components tend to be 5V.Also my primary component source is eBay since it has little or no shipping costs to my country, unlike other distributors like digikey that asks some ridiculous amount of money to ship just a single chip.Any candidates that fit that requirements?

author: Marco
author_rank: Super Contributor
timestamp: August 19, 2013, 06:41:16 pm
content: STM32F4DISCOVERY?Floating point and DSP instructions.

author: hans
author_rank: Super Contributor
timestamp: August 19, 2013, 10:09:12 pm
content: Note that most modern CPU's run at 3.3V or lower, not 5V. Especially if they have high throughput speed (MIPS) they will typically come in 3.3V specifications.Maybe there is a way you can level shift your signals, or find alternative peripherals for your project that work at 3.3V?As for the chip itself, STM32F4 discovery is a nice development board with great speed. It has an FPU (Floating Point Unit) which makes it possible to calculations using floats instead of integers. 160MHz or so is also very fast.dsPIC's are slower, but available in 28-pin DIP (dsPIC33FJ128GP804). That particular chip is also compatible with PICKIT2, even with debugging.None of the MCU's run at 5V

author: Stonent
author_rank: Super Contributor
timestamp: August 19, 2013, 10:18:00 pm
content: The TI Stellaris Launchpad is selling for under $10 USD right now and they have some DSP functionality or at least has the functionality via the headers (may be emulated, I'm not sure)http://www.ti.com/lit/an/spma041b/spma041b.pdfhttp://www.arm.com/products/processors/cortex-m/cortex-microcontroller-software-interface-standard.phpDigiKey's Croatian site has it for salehttp://www.digikey.com.hr/hr/en/digihome.htmlSearch for EK-LM4F120XLArrow, EBV Elektronik, Farnell, Scanti Rus also carry it. You might see if they have any better shipping prices than Digikey or try to purchase directly from TI.http://www.ti.com/tool/ek-lm4f120xl#thisI know when the MSP430 Launchpad was selling for $4.30 USD I think Dave said they included shipping so this may as well.

author: senso
author_rank: Frequent Contributor
timestamp: August 19, 2013, 11:02:06 pm
content: Go for the STM32F4, much faster and capable that any dsPIC will ever be.

author: Dajgoro
author_rank: Frequent Contributor
timestamp: August 20, 2013, 01:57:38 am
content: Quote from: senso on August 19, 2013, 11:02:06 pmThey look nice, and the inputs are 5V tolerant, and that is important to me. If the output is 3.3V that is near ttl levels, and it is not an issue, the biggest issue is the 5V input tolerance.None of the STM32F4 seems to be available in dip packages, but I could probably find an adapter board on ebay.I don't like using dev boards in my projects, because I am always trying to integrate the circuits on a smallest possible surface, so that I don't end up with a bulky contraption."8080/6800 modes", oh, I like that a lot, I have lots of such peripherals.Can the LQFP be soldered on a TQFP layout?http://www.ebay.com/itm/1-x-TQFP-144-TQFP144-Adapter-PCB-SMD-convert-Pitch-0-5-mm-/321134451401?pt=LH_DefaultDomain_0&hash=item4ac51adac9I also can't find the chip itself on ebay, so if I go for that I should find another part source.Also how it is programed?Also are there any other chips, maybe some older chips?

author: senso
author_rank: Frequent Contributor
timestamp: August 20, 2013, 02:04:54 am
content: Devboards are not really intended to be used as final projects, they are so you have a know working hardware, so you can develop your code with confidence in the hardware.If you want small projects, using DIP is not the way to go.

author: Dajgoro
author_rank: Frequent Contributor
timestamp: August 20, 2013, 02:11:36 am
content: DIP is the way to go when you are building stuff at home on a low budget.I agree that a decent device should have a proper pcb and all of the chips in their original package, but when you are just building experimental stuff on a budget, through hole is the way to go. Unless you have high speed signals.

author: senso
author_rank: Frequent Contributor
timestamp: August 20, 2013, 02:45:21 am
content: Almost every chip is cheaper in SMD packages, but they might require profissional made pcb's and can be a killer, so I totally understand your side.

author: edavid
author_rank: Super Contributor
timestamp: August 20, 2013, 03:43:42 am
content: Quote from: Stonent on August 19, 2013, 10:18:00 pmThe C2000 Launchpad went on sale for $8.50 today:http://e2e.ti.com/group/maketheswitch/b/blog/archive/2013/08/19/happy-birthday-c2000-launchpad.aspxNot what the OP wanted, but a good deal for a DSP board...