Microcontroller vs fpga

[odell]

Hi
I working on a  project using a 7in lcd. I was going to use a pic 32 but I saw a video on fpga. what is better and easyer

[Psi]

Does your 7" LCD have a built in controller with its own memory and API?  If so you can talk to it with a micro just fine.
But if it's a raw screen then you will need something with a bit more power to keep up with the LCD clock rates and a FPGA could definitely do that if needed.

But typically you only use a FPGA over a MCU when you have a need for one.

[odell]

here is the lcd I'm looking at
http://www.ebay.com/itm/STM32-Dev-Board-7-TFT-LCD-Module-1GB-TF-Card-/190459966375?pt=LH_DefaultDomain_0&hash=item2c584c73a7

[Psi]

That's got its own STM32F103VET6 ARM microcontroller plus a SSD1963 LCD Controller.
The dev board datasheet URL doesn't work for me so I'm not sure if the ARM micro on that board comes pre-programmed with a graphics API for external access or not.
If it does then you could use an external AVR/PIC to easily draw stuff on the lcd using serial API calls to the ARM.

However, if the ARM is blank then you will have to write your code into the ARM itself.
Doing that will be more work as you will have to read through the SSD1963 LCD Controller datasheet and write your own ARM LCD driver code to talk to the lcd controller IC. You would also need a JTAG programmer to work with the ARM chip.

[olsenn]

You definately don't NEED an fpga for this task, but they are great and can be used instead of the onboard ARM CPU and controller. Your call.

[joelby]

I wouldn't recommend using an FPGA to anyone who wasn't already proficient in using them, unless you have loads of spare time or are considering an application that would benefit from one. The learning curve is considerably higher than that of microcontrollers.

The STM development board looks nice - you might be able to get away with using it for the whole project. The only problem with buying development boards like this from China is that the documentation can be bad/non-existent/in Chinese, support can be limited, and there is likely to be no community of other users offering solutions for your problems.

[olsenn]

I have to disagree with this. From my experience, FPGA's can be even easier to use than micros. With conventional processors you need to learn what hardware capabilities the individual chip has (which means a program written for one micro won't likely work for another). Even when using a higher level language, like C, the specific registers et cetera still must be configured properly.

I'm not going to say that FPGA's don't have some individual preferences that need to be set, but often a net list and timing constraints file is provided by the manufacturer. With an FPGA, you program (basically) in raw logic (AND/OR/NAND/NOR/XOR/ flip-flops et cetera). Besides the near limitless power of the architecture, once you learn Verilog or VHDL, you can easily port your design to any other FPGA (as long as it has enough logic cells to contain your design). Some macros specific to the chip (Xilinx, Alterra...) exist, but most things can be done without using those.

Check out the Digilent Atlys (digilentinc.com) or the Terasic DE0/DE0 Nano (http://www.terasic.com.tw/en/).

One thing I will say about FPGA's in general, is that they take more power to run than microcontrollers, and they are not as cheap, so if you plan on selling your design, try to implement it in a cpu before an fpga. But if you're a hobbyist just making stuff for your own intrest/education, give an fpga a shot. You won't regret it!

[olsenn]

I forgot to mention, another board you may be interested in is the Altium Nano-Board 3000 (http://www.amazon.com/Altium-NB3000XN-NanoBoard-Xilinx-Spartan-3AN/dp/B0036SF9PE). It's less powerful than the other two i recommended, but it is more equipped (even has it's own touch screen lcd) and includes a 12-month license to Altium Designer.

[nasrmiad]

I think that using an FPGA to drive an LCD is too much effort. FPGAs are very complex devices and they can perform very complex digital circuits. FPGAs are more expensive, more difficult to write code for, and consumes more power.

 I say for a simple task of driving an LCD an MCU is more than enough.

[mikeselectricstuff]

I think that using an FPGA to drive an LCD is too much effort. FPGAs are very complex devices and they can perform very complex digital circuits. FPGAs are more expensive, more difficult to write code for, and consumes more power.

 I say for a simple task of driving an LCD an MCU is more than enough.

That would depend a lot on the LCD resolution, and what you wanted to display.
For example displaying bitmap images from flash on a small TFT panel, an FPGA is way simpler, cheaper and faster than an MCU capable of driving that LCD.
If you want to draw lines etc., an MCU with internal or external LCD controller is probably more appropriate. 
 

[EEVblog]

Most people would be in agreement that microcontrollers are simpler easier to develop with, if you have to ask such a question. FPGA's are more complex in almost every respect - tools, packages, languages, device configuration etc.
You'd only use an FPGA if you had to for a specific reason.

Dave.

[EEVblog]

here is the lcd I'm looking at
http://www.ebay.com/itm/STM32-Dev-Board-7-TFT-LCD-Module-1GB-TF-Card-/190459966375?pt=LH_DefaultDomain_0&hash=item2c584c73a7

That comes with am ARM development, so seems like your choice is made!

Dave.

[nasrmiad]

I think that using an FPGA to drive an LCD is too much effort. FPGAs are very complex devices and they can perform very complex digital circuits. FPGAs are more expensive, more difficult to write code for, and consumes more power.

 I say for a simple task of driving an LCD an MCU is more than enough.

That would depend a lot on the LCD resolution, and what you wanted to display.
For example displaying bitmap images from flash on a small TFT panel, an FPGA is way simpler, cheaper and faster than an MCU capable of driving that LCD.
If you want to draw lines etc., an MCU with internal or external LCD controller is probably more appropriate. 
 

Yes I definitely agree with you. If you want to drive something like a VGA display, then definitely go for an FPGA.

[slateraptor]

I forgot to mention, another board you may be interested in is the Altium Nano-Board 3000

LOL!