Author Topic: Highly anticipated low-end MCUs  (Read 28556 times)

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Offline Corporate666

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Re: Highly anticipated low-end MCUs
« Reply #100 on: April 11, 2014, 08:05:59 am »
i have done it myself, and its VERY easy. 2 minutes with a $3 reball kit and embossing heat gun. i just find it amusing that anyone would consider paying that to play with a $1 chip. specially when a short session on eagle and 1 week turnaround with osh would get a few made for about 1/20th that cost. of course places like that will always take advantage of those with money to burn and little sense of value.

When it comes to value, you have to consider the big picture.  If I was paying an EE to develop a device, and he proudly told me he spent just a half hour and whipped up his own BGA/DIP adapter and it would be here next week, I'd be pretty upset.  $20 for something that you can buy off the shelf, know it works, and get it right away is really a very small price to pay for anyone but a pure hobbyist, but I doubt most hobbyists are using fine pitch BGA's anyway.

I do wish the manufacturers would make "proto packages" though - I can understand not wanting to manufacture DIP/QFP or such for hobbyists, but it would be nice if they had some BGA's reflowed into DIP adapter boards in stock and ready to go for the hobbyist.  After all, even quite complex designs have engineers working on them in their office/lab before BGA production chips are ever used in pick/placed volume production.
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Offline tjaeger

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Re: Highly anticipated low-end MCUs
« Reply #101 on: April 11, 2014, 08:11:45 am »
When it comes to value, you have to consider the big picture.  If I was paying an EE to develop a device, and he proudly told me he spent just a half hour and whipped up his own BGA/DIP adapter and it would be here next week, I'd be pretty upset.  $20 for something that you can buy off the shelf, know it works (emphasis mine), and get it right away is really a very small price to pay for anyone but a pure hobbyist, but I doubt most hobbyists are using fine pitch BGA's anyway.

But how do you know it's going to work without proper decoupling?
 

Offline dannyf

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Re: Highly anticipated low-end MCUs
« Reply #102 on: April 11, 2014, 10:56:01 am »
Quote
But how do you know it's going to work without proper decoupling?

We know for sure that it's not going to work without proper XYZ - XYZ being anything you care to put there.
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Offline kert

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Re: Highly anticipated low-end MCUs
« Reply #103 on: April 11, 2014, 03:53:22 pm »
If I was paying an EE to develop a device, and he proudly told me he spent just a half hour and whipped up his own BGA/DIP adapter and it would be here next week, I'd be pretty upset.  ...
Agreed. In general, i have noticed that for most prototyping tools if it costs less than 50 bucks or so, my own time spent recreating them will be more expensive - especially if its just a one off curiosity investigation.
An ATmega328P in a DIP socket for $25 is LOL expensive too, nevertheless i have a bunch of Arduinos ( and a myriad of other quick proto kits ) around here.

 

Offline tjaeger

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Re: Highly anticipated low-end MCUs
« Reply #104 on: April 11, 2014, 04:04:40 pm »
Quote
But how do you know it's going to work without proper decoupling?

We know for sure that it's not going to work without proper XYZ - XYZ being anything you care to put there.

The point being that it's going to be tough to implement proper decoupling on a breakout board -- there's no guarantee that the traces from the power pins are short or even stay close together (although you might get lucky here because there are 16 ways to place the chip, but then again, you also have separate digital and analog supply, so good luck).
 

Offline Kjelt

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Re: Highly anticipated low-end MCUs
« Reply #105 on: April 11, 2014, 05:41:08 pm »
When using these boards I always glue some smd caps on the chip and connect them with very thin teflon wire to decouple the chips.
 

Offline tjaeger

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Re: Highly anticipated low-end MCUs
« Reply #106 on: April 11, 2014, 10:18:33 pm »
When using these boards I always glue some smd caps on the chip and connect them with very thin teflon wire to decouple the chips.
I still don't see how this would work with a BGA chip.  You'd have to scrape off the solder mask or something.
 

Offline Kjelt

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Re: Highly anticipated low-end MCUs
« Reply #107 on: April 12, 2014, 07:49:22 am »
Ah sorry for BGA indeed you have to clean pcb traces where available and hope your close enough to the pins. For prototyping it is not very critical in my experience, a hang or fault once a day is not a dealbreaker. The purpose is to gain experience with the chip. But in that case a smaller breakout pcb with pins close to the chip would be better.
 

Offline westfw

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Re: Highly anticipated low-end MCUs
« Reply #108 on: April 12, 2014, 10:27:41 am »
I have to say that I really like the trend toward "little" eval boards that plug into USB and sell for 'cheap.'  I think TI started it with the 430F2013 USB stick, and the Cypress boards that have been mentioned are an excellent example.  All pins available, usable but minimalistic programming interface, and easy to play with.  If NXP put their LPC1102 on a DIP18 adapter with some decoupling and a serial bootloader, and sold it for $5, I'd be pretty happy.  The price-point bar is pretty low, though.  The LPCXPresso boards are only about $20, and so are for-profit boards like the "Teensy 3."  $30 bucks for a mount-it-yourself bga adapter+chip isn't horrible if you really want to work with that chip, but it's not an enticing toy or impulse purchase, either.

I generally observe that if you want to catch engineers' imaginations and lure them to being interested in your products, you almost need to treat them like hobbyists.  The number of occasions where a company or engineer will actually "evaluate" a wide range of chips/vendors using their "eval board" type offerings is very small.  Usually you get a decision made based on someone's PRIOR or company legacy experiences (ranging from "I used an arduino in HS; let's use an AVR" to "our code base is 100k lines of code written for a 68000 that no one paid much attention to making portable.  We're for damned sure stuck with a big-endian 32bit word chip and some new 68xxx compatible like CPU32 sounds a lot better than something more different."

(now, the BIG eval boards come in handy prototyping your software while your HW design is percolating through its cycle.   The aforehinted 68k product had as much of its core as possible brought up on a 68331 eval board before the HW was done, and took about two days to get running on the actual HW when it came in.)
 

Offline kert

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Re: Highly anticipated low-end MCUs
« Reply #109 on: April 14, 2014, 08:53:06 pm »
The LPCXPresso boards are only about $20, and so are for-profit boards like the "Teensy 3."  $30 bucks for a mount-it-yourself bga adapter+chip isn't horrible if you really want to work with that chip, but it's not an enticing toy or impulse purchase, either.

Actually if someone tried to make a new Lilypad with micro connectors and a Cortex mcu,  sort of like Digistump Digispark or SquareWear 2.0 but even smaller, i'd be all for it. The ultimate micro proto board.
 

Offline dannyf

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Re: Highly anticipated low-end MCUs
« Reply #110 on: April 18, 2014, 12:14:38 am »
I suspect that you can simply compile it as other F4 chips and load the code to the chip.

Worst comes to work, compile it as a generic m4 chip, use the f4 start-up code and the F4 stdperiph library.

BTW, my Keil supports it.
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Offline chris0822

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Re: Highly anticipated low-end MCUs
« Reply #111 on: April 18, 2014, 12:31:42 pm »
I got one of those STM32F429 Discovery boards for free at a ST Seminar.  I would be careful ordering it since a decent number of them at the seminar had faulty LCD displays.  Seems like it was a manufacturing issue so it's possible they have been corrected by now.

We used a time limited version of Keil to compile code for it, but I will try CoIDE when I get a chance as that is what I've used in the past with other ST Discovery boards.  The debugger seems to work really well with built in ST Link programmer.
 

Offline kert

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Re: Highly anticipated low-end MCUs
« Reply #112 on: April 18, 2014, 07:25:34 pm »
The point being that it's going to be tough to implement proper decoupling on a breakout board -- there's no guarantee that the traces from the power pins are short or even stay close together (although you might get lucky here because there are 16 ways to place the chip, but then again, you also have separate digital and analog supply, so good luck).
Got the demos from protoboard, pic attached. They couldnt find a 0.4mm pitch freescale part, so had to substitute for qfn.
The NXP one looks super cool and tiny though. Possibly could solder this with a hotair rework station on my own board, but it would be a bit of crapshoot i guess.
Unfortunately it will have to wait several weeks before i can spend time attempting to power these up though.
 

Offline BloodyCactus

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Re: Highly anticipated low-end MCUs
« Reply #113 on: April 21, 2014, 05:31:30 pm »
I'm looking forward to the Propeller2!
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