Very cheap Mega128A board

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#1
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I couldn't resist ordering one of these boards:

http://www.ebay.co.uk/itm/151278...

for £9.30 including postage.

I'll let you know what I think of it when it arrives.

It seems to be based on this PCB from ITEAD:

http://imall.iteadstudio.com/ope...

Leon Heller G1HSM

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Quote:
for £9.30 including postage.

Mind this is m128 (non-A) so it is supposed to work only on 5V (according to DS). The m128A operates in 2.7-5.5V range.

I see some discrepancy about this board.

For a complete noob m128 is an overkill.
Most noobs won't be even able to RTFM of m128, not mentioning respective ANs. It is just too big.

M32 or M162 in PDIP + breadboard are IMHO better noob propositions (JTAGICEMk1) as one can buy 5 of them for £10 locally and it is very easy to wire that. Of course if someone owns Mk2 and up then m1284-PU is always a noob winner.

And for someone who wants something serious - wouldn't it be grand if it had at least 32kB of external SRAM?

No RSTDISBL, no fun!

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It says it is an ATmega128A.

It isn't claimed to be intended for beginners.

Leon Heller G1HSM

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leon_heller wrote:
It says it is an ATmega128A.
But the photo of the board shows an ATmega128.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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Quote:
It says it is an ATmega128A.

OTOH the picture and some of the description mentions m128 (non-A). Ask the seller, just to make sure.

Anyway, it is definitely usable.
They have also routed PEN to pin header!
rqyem

No RSTDISBL, no fun!

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Quote:

For a complete noob m128 is an overkill.

Why? If I was a beginner these days I'd probably buy a mega1284P. Nothing says you HAVE to use every last resource in it but on the day you wire it up to an SD and a GLCD and want to do picture decompression or something that 16K RAM sure is going to help things along! Admittedly it looks like a waste of resource if you simply flash an LED with a soft delay. But if you were only buying one chip/board does it really matter if it's $2 or $10 ?

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The photo shows a chip manufactured in 2006.
I would guess that current deliveries will use recent chips. e.g. mega128A

I am sure that Leon will get on fine with the bare dev board.
However, for a similar amount of money, you could buy an Arduino MEGA clone e.g. [url]http://www.ebay.co.uk/itm/Mega-2560-R3-ATmega2560-16AU-Board-Arduino-com... for £10.95 from UK
or [url]http://www.ebay.co.uk/itm/Microcontroller-Board-ATmega2560-16AU-USB-Cabl... for £8.55 from China.

Ok. You need an ATMEL-ICE, JTAGICE-3, DRAGON, ... to run the JTAG.

But personally, I find that the built-in UART comms + bootloader make any regular Arduino ideal for prototyping. And of course, all the shields are interchangeable.

And actually, I prefer the UNO as a general purpose platform.

David.

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Quote:
Nothing says you HAVE to use every last resource in it

True but for me it is always a matter of comparing alternatives (relative values):
    Mentioned m128 or other goodies.
and not the decision if something is worth £2 as such (in absolute value).

So if I were to chose some stuff for playing with avr8s then it is either a bucket of m16/m32 or one m128+SRAM. But it is mood dependent.

No RSTDISBL, no fun!

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leon_heller wrote:
It isn't claimed to be intended for beginners.

Indeed - and I would strongly recommend that beginners should avoid cheap stuff like this.

Just look at their description:

leader-foreign-trade-llc wrote:

2. The AD transform reference voltage added filter inductance and capacitance;
3. Through the jump line can choose different frequency external crystals;
4. All are drawn and mark IO mouth;
5. ISP and JTAG interface are drawn and mark;
6. Reliable reset circuit;
7. PA1, PA0 out two LED for simple test

A reasonably experienced user can draw some sense from that gibberish - but it's not going to help a beginner.

If there is any documentation, it's likely to be to a similar standard - again, not helpful for a beginner.

And support? Forget it!

This is why they're so cheap :!:

#NoSuchThingAsAFreeLunch

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The board has just been delivered. It has got a Mega 128A.

Leon Heller G1HSM

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I make that 9 days delivery. Pretty good service from China Post!

And I bet the date code on the 128A is 2014.

David.

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The only marking that looks like a date code is AU 1333. Does that make any sense?

Leon Heller G1HSM

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Week 33, Year 2013.

So I do NOT win a coconut!

David.

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That's good to know. The earlier chips seem to have had several errata.

Leon Heller G1HSM