09-10-2017 08:55 AM
am varunjohnson, working at Robert Bosch , we have a requirement for creating a front end using Custom Low cost FPGA Automotive standard , i have mentioned the basic requirements that i am aware below .
1). 16 bit uC
2). Communication peripherals such as SPI ,i2C, ..
4). logic gates
i have less / no experience in FPGA topic , kindly guide me with points that are required for Custom FPGA ,so i can collect you the actual requirements from our side and we can work together for a complete solution .
awaiting for your extended support
09-10-2017 12:20 PM
Why 16 bit uC? As far as I know these needs - assuming you don't have so much complex logic- could be handled on a CPLD!.
Below are some specifications you can gain by using such very low cost/complexity system which also eases the use of FPGA for a person who wants to begin from the very beginning:
I just wanted to imply that your needs may be as low as CPLD resources and by using it instead of FPGA you can save time for developing the board and coding. Otherwise, please specify your required speed and a rough estimate of gate in your final design. How much capacity your memory should be and how fast?
Another microcontroller/processor which can be deployed on Xilinx FPGAs - not the CPLD - is MicroBlaze. If you can't make do with the limitations of PicoBlaze you ought to use FPGA.
Hope this will help,
09-11-2017 04:30 AM
It might make more sense to start at a higher level. What task are you aiming to do with the FPGA?
Pretty much any FPGA could meet the requirements you laid out - but so could a cheap MSP430, PIC24, or AVR Xmega microcontroller. If those requirements are all you need, an MSP430 will be easier to implement and much cheaper.
09-13-2017 12:07 PM
As this user has made a list of its requirements, microcontrollers can't do do logic!.
4). logic gates
They are also unable to deliver vary large amount of memory except to those more advanced ones that will cost more as well. So, I suggested the most optimum and the lowest cost as well.
09-13-2017 05:07 PM
@embedded Depends on the type of logic! Lots of microcontrollers have a very small amount semi-programmable logic inside, and some (eg. the Cypress PSoC chips) actually have a reasonably large amount of it. And, of course, for simple logic you can always just emulate it on the CPU.
With regards to the memory, we really need to know how much he needs (and what bandwidth). For <1MB of flash/RAM accessed at low speed, a microcontroller will be vastly easier and cheaper than an FPGA (because you can get a single-chip microcontroller with everything built-in, using a single power supply, programmed with a completely free toolchain). For the 16 - 128MB region either could be acceptable (the bigger STM32 chips have a built-in memory controller, and the PIC32MZ has up to 32MB SDRAM built-in) - but microcontrollers are cheaper and easier to design with. If he's after 1GB+ RAM accessed at over 1GB/s then an FPGA is a very clear winner; I'm not aware of any microcontroller that can handle that sort of performance.
09-13-2017 09:55 PM
Thank you for your information regarding different uCs and their memories. I am not aware of Cypress PSoc. However, I doubt those mentioned uCs have logic inside - the first ones you had mentioned MSP430, PIC24,.. Logics are real time and CPUs can't run like that.
For other part of your comments I agree with you. we need to know how much capacity they need.
09-13-2017 11:38 PM
@embedded Again, it depends on both the sort of logic needed and to what extent it has to be realtime.
An example of where a CPLD used to be really useful was quadrature decoding, because this often does demand extremely high performance and an AVR or PIC often won't keep up. However, many of the new ARM-based CPUs can be configured to do quadrature decoding, or even have dedicated hardware just for that purpose.
With the timing, I can imagine an obvious example of a 5-input logical OR gate - the door-open sensors on a car (if one or more door is open, turn on the "door open" warning light on the dashboard). However, any time under about 100ms is effectively "instant" for this - an MSP430 could do it just as well as a true OR gate.
Of course, it's very possible that his demands don't fit with what a microcontroller can do, in which case an FPGA is definitely a good option. However, given the large cost savings from avoiding an FPGA, it's worth verifying that it's actually required before selecting one.
09-19-2017 03:16 AM
Thankyou for the feedback , we are in a discussion on whether a CPLD could solve our requirement ,our current project requirement is mentioned below
1). An analog front end for PLC communication (power line communication)
2). example ,current we are trailing out with an evaluation board which has a processor (freescale) and an PLC chip for power line communication , we plan to make a custom bulid FPGA /CPLD to suit this requirement .
the interface between the processor and the PLC chip is SPI ( we intend to use other communication interfaces too ex UART ,LIN CAN.. )
we are basically from an Automotive background , so i dont think a microcontroller alone can suit our requirement .
i wish to get an list of the parameters (ex memory , gates , communication modules etc .. ) which are basically required for choosing an FPGA .