ARM DIP package at US1,26 to the rescue

The LPC1114FN28/102 is now available for US1,26 in one off qttys.
It is a skinny DIP28 with 32k flash and 4k sram. 50MHz operational freq.
Here is a short piece, and the links lead all the way to the embedded hello world : the flashing LED.
[hackaday.com]
The only question : is 32k on an ARM enough?

That's great news! I think it will be a popular chip. I have found the NXP ARM chips quite nice to use.

No, 32KB is not much for an ARM. A typical RepRap firmware takes 40-60KB. The Cortex-M0 is the "entry level" ARM core as well, no hardware divide for example. But really this chip is competing with all the 8/16 bit offerings in its price range. For barely more than a $1, it provides a lot of capability.

More importantly for my POV, there is a range from of CPUs from M0 to M4F which span a decent range of cost and performance with essentially the same toolset.

Teacup firmware can compile into something like 14k flash and 1k RAM on the ATmega. As many operations are 32-bit, it might get even smaller on a 32-bit CPU. At least it's worth a try. The R2C2 guys have ported Teacup to ARM already. Probably they didn't care much about keeping the binary small, but the tricky parts like operating the I/O pins should be usable.

Another question: can we get away with 22 I/O pins, just one ADC and without PWM?

BTW., this chip doesn't support direct USB? That would be really disappointing.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Our commercial core, RepRapPro, has also thought about going ARM: [blog.reprap.org]

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

6x 10 bit ADC's
4x pwm
For pin expansion I'd use the spi on a 74hc595, cheap, available and infinitely expandable.
No USB unfortunately, only a serial port. We can use something like this [www.recursion.jp] to allow USB with cheap DIP parts, although it is one more microcontroller that needs to be programmed, albeit only once.

The data sheet is here: [www.nxp.com]

It states: "10-bit ADC with input multiplexing among 5, 6, or 8 pins depending on package size." So, one ADC which can be switched between a number of pins. And the term "PWM" can be found nowhere in this document. Undoubtly this CPU has advantages, but also shortcomings compared to an ATmega.

Did you find a different data sheet?

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

The ADC is multiplexed just like the ADC on the AVR.
Scanning the ACD inputs is the firmware's job.

The PWMs are implemented in any of the 4 timer / counters just like in the AVR. PWM is achieved by setting the timer counter match compare registers to toggle on match. On the 28pin dip package there are 12 match outputs.

In embedded programming a word scan is not enough to identify the capabilities of a processor, not all manufacturer's use the same terminology in some cases intentionally (like Atmel, calling their I2c a TWI) for copyright / patent reasons, in other cases names change because the hardware can be used for many different applications, PWM, timing etc The names and implementation may change, but the functionality is there.

... long ago, when microcontrollers as 6502 or 8031 didn't have such features as ADC's or PWM this was solved by adding the wished functionality by a discrete chip ... mostly with complete data-/adress-busses or even intreface-chips.

I think, this (beside of driving LCD's and SD's) is the main reason, modern MC's support serial communication as SPI, I2C/TWI or older - simply hook a more powerfull device to the bus, if the inbuilt 10Bit-ADC isn't enough ...

I'm sort of 'spoiled' by fast (200ks/s) 16- and 24Bit-ADC's (or 'unlimited' accuracy with Sigma-Delta-ADC's) in my normally used C51-MC's, so more interested in adding higher accuracy ADC's or high-current-drivers to the Arduino or other common platform ...

Edited 1 time(s). Last edit at 10/12/2012 02:35AM by VDX.

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

OK, so the question is, who is starting the Gen8T design? and who's crazy enough to start porting a firmware?

*lol*

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Someones gotta be voluntold

Nothing against the current arm designs, but they're designed to be factory built, and non replaceable drivers can make a board useless fast... and DIY is better

Edit, no I don't mean to sound like that I'll happily give it a whirl, but I'm no EE

Edited 1 time(s). Last edit at 10/13/2012 03:46PM by hephaestus.

I don't know where you draw the line, but I am designing an ARM board which is intended for DIY construction. Of course, DIY implies a certain level of skill, but DIY SMD assembly is more about method than special equipment. I am also making it modular, as this does give flexibility.

On the software side, I am just looking at ARM ports. The ARM ports so far are either large (C++...) or ported for specific chips. I am planning to use ChibiOS, which is GPL, lighweight and already has support for a number of ARM chips. It may also be possible to run ChibiOS on some AVR parts, not sure the state of that.

I also suggested the possibility of making an ARM module to plug into a 40 pin DIL socket, but I wouldn't use the mBed module, it's relatively expensive and while has good libraries, it is tied in to the online compiler, unless you spend extra effort detangling it.

Nope I'm anxiously awaiting sango-bc But I also realize DIP components are much easier for many of us (Especially me, I'm not good at fine soldering; I can barely do DIP some days) Luckily I have access to some toys...

I was just pondering how hard it would be - to make a 'daughter board' with the LPC1114FN28 - so it plugs right into the Gen7, in place of the ATMEL... add a 3.3v regulator, and a couple bi-directional level converters... Adds complexity, but then it's a drop in replacement for almost all generations of reprap hardware...

bobc Wrote:
-------------------------------------------------------
> I am
> planning to use ChibiOS, which is GPL, lighweight
> and already has support for a number of ARM chips.
> It may also be possible to run ChibiOS on some AVR
> parts, not sure the state of that.

While I haven't used ChibiOS, I can tell you for sure that FreeRTOS's "support" of ARM chips is a joke. It breaks down to "supporting" the systick timer. I had to write my own "drivers" for everything else.

> I also suggested the possibility of making an ARM
> module to plug into a 40 pin DIL socket, but I
> wouldn't use the mBed module, it's relatively
> expensive and while has good libraries, it is tied
> in to the online compiler, unless you spend extra
> effort detangling it.

Have you looked at the STM32 discovery boards? Or the LPCXpresso? I'd lean towards discovery instead of LPCXpresso since ST-LINK is supported by openocd and LPC-LINK is not.

Another place to look is Olimex. If it has enough I/O and processing power, this might work: [www.olimex.com]

PWM Can be implemented in software.

This has a Nested Vectored Interrupt Controller, So running a fast interrupt process to implement the switching, assuming the I/O can handle it.